US2825061A - Wave radiator - Google Patents

Description

Feb. 25, 1958 H. J. ROWLAND WAVE RADIATOR 9 Sheets-Sheet 1 Filed Nov. 21 1951 [rave rater my 8 Z i Feb. 25, 1958 Filed Nov. 21 1951 H. J. ROWLAND WAVE RADIATOR 9 Sheets-Sheet 2 Feb. 25, 1958 H. J. ROWLAND WAVE RADIATOR 9 Sheets-Sheet 4 Filed Nov. 21, 1951 mz/er tor Haw/9RD J. KOWLAND I Feb. 25, 1958 H. J. ROWLAND v WAVE RADIATOR 9 Sheets-Sheet 5 Filed Nov. 21 1951 Feb. 25, 1958 H. J. ROWLAND 2,825,061

' WAVE RADIATOR Filed Nov. 21, 1951 9 shets-sneet e H. J. ROWLAND WAVE RADIATOR Feb. 25, 1958 Filed Nov. 21 1951 9 Sheets-Sheet 7 v1210,6380?" How/m0 "T zqwmup w r A M Q w f wzfi Q. H f f .M/ Q l R J 5 on $1 Q, b v: m L 5 2? M Q N M; ,y M a? 5 z 1 I 1 1 A r Feb. 25 1958 H. J ROWLAND 2,825,061

v WAVE RADIATOR Filed Nov. 21, 1951 9 Sheets-Sheet 9 "9 i I f? jiZZZVZZO? 4 HOWARD I QOWLRND 0Y4 /f M aaxm m .5

United States Patent WAVE RADIATOR Howard J. Rowland, Brookline, Mass., assignor, by mesne assignments, to The Gabriel Company, Cleveland, Ohio, a corporation of Ohio Application November 21, 1951, Serial No. 257,547

26 Claims. (Cl. 343-770) This application is a continuation-in-part of application Serial No. 28,115, filed May 20, 1948, by Howard J. Rowland, now abandoned, and application Serial No. 28,116, filed May 20, 1948, by Howard J. Rowland, now abandoned.

For the purpose of radiating electromagnetic waves especially in the frequency modulation and television wave length ranges various types of antennas have been proposed which, although theoretically more or less satisfactory, present various practical difficulties based on inherent features of electrical as well as mechanical construction. These known antennas involve more or less complicated structures which are expensive, look awkward, are rather high and heavy, offer high Wind loads, are liable to break down in winter because of icing, present difliculties in erecting and adjusting for proper operation, need frequent repair, cannot be made as nondirectional as desirable, and are not as efficient as might be expected, their gain per unit of antenna height being rather unfavorable. This is particularly true of nondirectional antennas which are, generally speaking, mechanically as well as electrically more complex than the directional antennas of cognate type.

It is a principal object of the present invention to provide antennas for radiating uniformly with reference to horizontal planes, energy of comparatively short wave lengths particularly for television and frequency modulation purposes, which antennas are mechanically very simple and yet electrically fully satisfactory, which have gain properties at least equivalent to those of conventional antennas for similar purposes, which can be manufactured and installed in several baysections of comparatively small size and low weight, which lend themselves to conventional fabrication from structural steel or aluminum shapes or other easily available strong and inexpensive material, which can be fed regardless of the number of sections by means of a single transmission line, which are adapted to radiate a broad frequency band, and which can be pretuned at the factory for any given frequency so that when installed'in the field no further electrical adjustments are required.

Other objects of the invention, related to mechanical properties, are to provide an antenna which consists essentially of a single self supporting tower structure without protruding elements liable to increase wind and ice loads, which reduces installation problems to a minimum since it can be manufactured at the factory in bay'sections, which is very rigid, which presents less wind load and weighs less than conventional antennas for similar purposes and at all comparable gain, which has low maintenance cost due to simplicity of construction and ruggedness, which has considerable eye appeal due to its neat and clean cut appearance, and which provides a convenient and attractive mounting foran obstruction beacon light.

Further'objects of the invention, related to electrical properties, are to provide an antenna of the above indidesired by stacking sections which are of increasing me chanical strength towards the lower end of the tower structure; to provide an antenna which emits horizontally polarized nondirectional radiation but can easily be modified for directional or nondirectional radiation and polar-ization in any desired plane; to provide an antenna whichpermits building up from uniform or dissimilar bay sections which can be combined as to number and spatial arrangement to furnish any desirable radiation pattern; to provide an antenna which furnishes an almost perfectly circular radiation pattern that is a pattern that is circular to better than a ratio of 1.1 to 1 in power; to provide an antenna with a low standing wave ratio at any selected frequency to which the antennas can be pretuned at the factory with accurate measurements of the standing wave ratio being made before shipping with accurate laboratory measuring equipment; and to provide an antenna which is not excessively frequency sensitive but has a wide band width, so that a single antenna suffices to cover an entire broadcasting band.

In one of the principal aspects of the present invention these results are accomplished by a device for radiating electromagnetic waves of an approximately given average length which radiator, of inherently very simple construction, comprises a metal frame having a shorter and a longer perimetric dimension, combined with a system supplying radio frequency energy with a field of given orientation placed to feed the frame with the plane of polarization of the field approximately perpendicular to the longer dimension of the frame, whereby the frame. emits a resultant electromagnetic wave which is polarized approximately perpendicular to the longer dimension of the frame. The thickness dimensions of the frame are appreciably smaller than its perimetric dimensions. The radiator frame may be made of simple wire or it may have tubular portions which may or may not serve asv mechanically supporting as well as electrically effective elements, or the radiator frame may be built up from structural steel or aluminum shapes such as channels or.

I-beams joined by simple castings or welded plates which. not only serve as mechanical spacers but also as parts.

of antennas according to the invention, the metalframe;

for example but not necessarily of generally rectangular shape, having a perimetric dimension which is longer and a perimetric dimension which is shorter than one half of said wave length, is combined with a system supplying radio frequency energy with a field of given orientation placed to feed the frame with the plane of polarization of the field approximately perpendicular to the longer dimension, whereby the frame emits a resultant electromagnetic wave which is polarized approximately perpen-,

dicular to this longer dimension. Although the antenna 'lar to said longer sides.

according to my invention is preferably rectangular, it may be square, oblongly round or circular, provided that the frame sides or segments which are perpendicular to the plane of polarization are longer than one half of a wave length to be radiated.

In an additional aspect, the invention provides for tuning of the radiator by combining a metal frame having two pairs of opposite shorter and longer sides respectively, with a system supplying radio frequency energy with a field of given orientation placed to feed the frame with the plane of polarization of the field approximately perpendicular to the longer sides, and with an impedance tuning connection along one of the longer sides, whereby the frame emits a resultant electromagnetic wave which is polarized approximately perpendicu- This tuning connection may represent a series or a parallel impedance, or both series and parallel tuningimpedances may be provided. If the radio frequency energy is supplied through coaxial conductors these tuning impedances may be open or short circuited. stubs whose outer conductor can be directly connected to and mechanically mounted on the frame structure.

In yet another very important aspect of the invention two or more frames of the above indicated type, sometimes also referred to as waveguide sections are combined, with the two metal frames having intersecting planes and each frame having a shorter and a longer dimension and the frames being associated with a sy tem supplying radio frequency energy with two fields of given orientations and phase relation placed to feed respective frames with the plane of polarization of each respective field approximately perpendicular to the longer dimension of the frame which it feeds. In this manner radiation fields of any desired pattern and polarization can be obtained in comparatively simple manner with structures incorporating all the above-mentioned mechanical and electrical features and advantages. In a specific instance of multiple frame antennas, two or more coplanar frames may be joined. Such coplanar frame antennas compress the radiation pattern in a plane through the longitudinal axis of the antenna. Another possibility of combining several frames is to put them in two or more parallel planes. Still further, the planes of frames may intersect, opposite sides of each frame being mechanically and electrically connected. A particularly useful embodiment of the last mentioned intersecting frame construction is a non-directional antenna which ,has a practically perfect circular radiation pattern in a plane normal to the longitudinal antenna axis. Such antennas have one or more units, also referred to as bay sections, each consisting of two substantially identical frames or waveguide sections which intersects at right angles and whose waves have a ninety degree phase difference.

In one of its more specific aspects the present invention accomplishes these results by means of bay sections which comprise two metallic antenna frame members of approximately equal size and rectangular shape which members intersect symmetrically at approximately right angles and are fed by a system supplying radio frequency energy with two. fields of given orientation with the same plane of polarization and 90 phase displacement placed to feed the respective frame members with the plane of polarization approximately perpendicular to the longer sides of the frames, whereby the bay section emits a resultant electromagnetic wave which is polarized approximately perpendicular to the longer sides of the frame members and of approximately equal energ in all radial directions in the plane :of polarization. The rectangular frames or wave guide sections of a particularly useful nondirectional bay section intersect with their shorter sides while transmission line components lead towards the longer sides; the intersecting sides may be formed by metallic plate elements common to both frame.

members and constituting mechanical supports or bases for channels or other rolled shapes or rod elements screwed or welded to the end plates to complete the frames. These frame rod elements may also constitute the outer conductors of coaxial lines and thus be used for feeding the frames as indicated above; if the frame sides are made from open rod structures these may support feed lines secured thereto, for example coaxial lines with the outer conductor clamped or welded to the webs of channels constituting the frame sides.

Several nondircctional bay sections can be stacked upon each other with perspective frames of the bays in rectangularly intersecting planes.

Generally speaking two or more frames or waveguide sections can be combined in any desired spatial and electrical phase relation to furnish arrays with correspondingly varied radiation patterns.

As will appear from the following detailed description, such structures do not present problems of cumbersome feed lines, since the feed system is either essentially a part of the frames or hardly longer or more complicated than that for a single frame.

In another more specific aspect, the invention concerns a wave radiator with two pairs of parallel elongated metal membcrs such as structural steel or aluminum shapes fastened with their ends to metal plates and defining with these plates two similar rectangular frames or wave guide sections symmetrically intersecting at right angles at the plates thus forming a complete nondirectional bay section; a transmission line having two conductors is electrically associated with the approximate centers of respective opposite members of one of the frames, and a branch of the transmission line of a length defining a 90 degree phase shift electrically is associatedwith the approximate centers of respective opposite members of the other frame. The energy supplying transmitting means may be a coaxial line lead ing towards the center of one of the longer frame members, for example channels, with the outer conductor of the line electrically connected to that channel and terminating thereon and with the inner conductor leading through an opening in the channel to the opposite channel where it terminates; a second coaxial line branches off forming a 90 degree phase shifting circuit element and leading towards the center of a third channel, with the outer conductor electrically connected to that channel and terminating thereon and with the inner conductor leading through an opening in the third channel to the opposite fourth channel where it terminates. It will be understood that any suitable impedance device can be iised instead of the phase shifting length of transmission In a further more specific aspect, a nondirectional wave radiator according to the invention comprises a plurality of metallic bay sections, each section including four flanged structural members such as aluminum or steel channels connected with their ends to metallic end pieces which may be cast or welded and with which the structural members define two similar rectangular wave guide sections symmetrically intersecting at right angles at the end pieces, respective structural members of adjacent bay sections being aligned and the end pieces of adjacent bay sections being joined; such a radiator can be supplied with energy through a coaxial transmission line approaching one of the structural members of one of the sections and running along aligned members with the outer component mechanically and electrically connected thereto, the inner component leading freely through the approximate centers of its structural members to the opposite members of the respective frames to which members it is electrically connected; the transmission line has branches or loops of a length defining a 90 degree phase shift leading from the line to the ends of the aligned adjacent structural members of the intern secting wave guide sections and running along these adjacent members with the outer component mechanically and electrically connected thereto, the inner conductors of these branches leading freely through the approximate centers of each respective structural member to its opposite member to which they are electrically connected. If several bay sections are used, phase shifting loops may be associated with each section or a single loop may serve to associate the two sets of coplanar frames.

As mentioned above, the coaxial feed and branch lines are preferably run along the frame sides such as channels; they may be fastened thereto by welding or with clamps. This construction can also be utilized, according to the invention, for providing tuning means. For that purpose, the coaxial lines are continued beyond the approximate midpoints of the respective longer frame members upon which they terminate, forming tuning stubs whose electrical characteristics are defined by plugs inserted between outer and inner conductors. Stubs extending from the termination points of outer conductors represent parallel reactances and those extending from points where inner conductors approach the respective opposite frame members, represent series reactances; it was found that in many instances parallel reactances are not required.

In an additional aspect of the invention, the wave radiator frames can be used with the feed points either in a vertical or a horizontalplane, for vertical or horizontal polarization. As a particularly useful practical embodiment of vertically polarized frames, radiators according to the invention can be incorporated in metallic structures for example body portions of vehicles. Such a radiator frame may include a metallic bail member mechanically and electrically joined to the body portion of the vehicle to define with the outer body contour an antenna frame, the two conductor elements of a transmission line terminating at regions in or near a vertical plane intersecting the frame.

These and other objects, aspects, and features of construction and operation will appear from the following description of several typical practical embodiments illustrating the novel characteristics of my invention. This description refers to drawings in which:

Figs. 1 and 2 are isometric views of two wave radiator frames according to the invention, fed by a dipole and a coaxial line respectively;

Figs. 3 and 4 indicate the horizontal and vertical radiation patterns respectively of antennas according to Figs. 1 and 2;

Fig. 5 is a diagrammatic representation of an antenna array consisting of two frames, with appropriate phase control connections to the transmission line;

Fig. 6 is a diagrammatical isometric view of an antenna array consisting of two parallel frames;

Fig. 7 is a diagrammatical isometric view of an antenna array consisting of two coplanar frames;

Fig. 8 is a diagrammatical isometric view of a nondirectional antenna bay section;

Fig. 9 is the horizontal radiation pattern of an antenna according to Fig. 8;

Fig. 10 is the top view of a nondirectional single bay section; I

Figs. 11a and 11b are side elevations of an antenna according to Fig. 10, viewed from opposite directions respectively as indicated by corresponding arrows a and b of Fig. 10;

Fig. 12 is a section of lines 12-12 of Fig. 11a;

Fig. 13 is a bottom view of Fig. 11a and shows a modified construction of the feeding system;

Fig. 14 is a schematical longitudinal section through a three bay directional antenna with tubular frame members;

Fig. 15 is the vertical radiation pattern of an antenna according to Fig. 14;

Fig, 16 is the isometric diagram of a nondirectional aszaoei antenna in mechanical construction similar to that shown in Fig. 14;

Fig. 17 is the isometric diagram of a antenna with central coaxial feed;

Fig. 18 is the isometric diagram of a nondirectional single section antenna analogous to that shown in Fig. 17;

Fig. 19 is a diagram of an antenna array with coplanar frames;

Fig. 20 is a bottom view of the array according to Fig. 19;

Fig. 21 is a side view of an array according to Fig. 19 indicating the vertical radiation pattern;

Fig. 22 is the isometric diagram of an antenna array with coplanar frames in several parallel planes;

Fig. 23 is the isometric diagram of a nondirectional antenna with vertical polarization;

Figs. 24, 25 and 26 are side view, front elevation, and top view, respectively, of a vehicle incorporating an antena according to the invention with the horizontal radiation pattern indicated in Fig. 26;

Fig. 27 is the isometric diagram of a nondirectional antenna with four bay sections built from structural steel or aluminum;

Figs. 28 and 29 are sections on lines 2828 and 2929 respectively of Fig. 27;

Figs. 30 and 31 are diagrams indicating two possibilities, respectively, of feeding antennas according to Figs. 27 to 29;

Fig. 32 is the diagram of an antenna frame according to Fig. 2 with coaxial feed along a frame side and with series and parallel tuning stubs;

Fig. 33 is a front elevation of a single bay section antenna according to the invention;

Fig. 34 is a section on lines 34-34 of Fig. 33;

Fig. 35 is a section on lines 35-35 of Fig. 33;

Fig. 36 is a side elevation of a two bay section antenna according to the invention, otherwise similar to the single bay section antenna shown in Figs. 33 to 35;

Fig. 37 is a section on lines 37-37 of Fig. 36;

Fig. 38 is a section on lines 3838 of Fig. 36;

Fig. 39 is an isometric diagram of the feed and tuning lines of the antenna according to Figs. 36 to 38;

Fig. 40 is a section on lines ill-40 of Fig. 36;

Fig. 41 is a detail, partly in section, of an inner conductor of the coaxial line such as shown in Fig. 40;

Fig. 42 is the front elevation of the top portion of an antenna such as shown in Figs. 33 and 36, but of welded instead of cast metal construction;

Figs. 43 and 44 correspond to Figs. 39 and 36 respectively, illustrating a two bay section antenna having a single phase shifting loop; and

Fig. 45 is a section on lines 45-45 of Fig. 44'.

Figs. 1 and 2 show simple basic embodiments of my invention which are presented in order to facilitate the explanation of the more complex embodiments specifically dealt with herein. These basic embodiments are single metallic frame or loop members F fed from a transmission line T with radio frequency energy. As indicated in Fig. 1, the feeding arrangement may consist of the two opposite wires 51 and 52 of a two-wire transmission line terminating in'a dipole system d. Any other convenient method of supplying radio frequency energy may be used; as for example shown in Fig. 2, the antenna may be supplied by a coaxial line with outer conductor 55 and inner conductor 56 leading to points a and b respectively of frame F. I found that frames of round wire as well as frames with tubular or flanged cross section are fully operative. In actual practice, frames fabricated of structural steel or aluminum shapes such as channels or I- beams and of rolled or cast plates have been found particularly useful and embodiments of these types will be single frame described in greater detail below.

I am at'the present time not absolutely certain can:

cerning the theory of wave radiation from such frame structures, but I believe that the frame can be regarded as a short section of wave guide open at bothends. For this reason it can also be termed a wave guide or antenna loop section. If lines x, y, z of Fig. 1 are regarded as the axes of a rectangular coordinate system, the wave guide surfaces can be assumed to extend in direction x having vanished in this direction for purposes of the present antenna which thus approaches the shape of a practically filamentary frame member, that is a frame member whosedimension in the direction x is very small as cornpared to the perimetric dimensions in directions y and z.

I found that in accordance with my invention, frame systems of this type constitute wave radiators having particularly favorable operating conditions if the field of the radio frequency energy fed tothe frame (such as that supplied by dipole system 51, 52, d or by coaxial conductors 55, 56) has a plane of polarization x, 1 which intersects the longer sides of the frame causing a current distribution as indicated in Fig. l with dotted lines i. As indicated in Fig. l, the high voltage points It and h are thus separated by wide gaps across the frame, which provides a very favorable construction so far as icing and similar detrimental effects are concerned; these points are in actually built antennas of this type separated by gaps of fifteen inches or more so that the icing danger becomes practically negligible. On the other hand the region where the feeding system approaches or is joined to the frame as for example at points a and b of Fig. 2, is one of low impedance across the frame, so that an accumulation of material at that region is of little consequence in spite of the short circuiting effect that such an accumulation might tend to introduce.

I found that the frame does not have to be rectangular; oval and even circular shapes perform fairly satisfactory. However the approximate length of theframe or loop segments or sides which intersect the plane of polarization should be one-half or more of the length of a wave to be radiated. The width of the antennadepends upon the radiation pattern desired and also upon the impedance characteristics of the system as a whole. Although the narrower sides of the frame or loop are usually shorter than one-half of the wave length, they are not necessarily so and,.as mentioned above the frame may be circular or square.

Fig. 2 indicates in addition to a coaxial feed line, practically valuable arrangement for tuning antennas of this type. In this figure, .9 represents a series reactancc and p a parallel reactance, which in this instance take the form of stubs. The stubs may be short circuited, that is, inner conductors 62 and :34 may be metallically connected to outer conductors 63 and 65, respectively, or the stubs may be open ended. It was found that tuning reactances of one type, particularly series reactances, are often sufficient, so that for example stub 62, 63 could be omitted from Fig. 2. it should be understood that, al' though the above indicated manner of connecting feed line and frame is particularly practical, the basic principle of operation of my wave guide frames can be achieved with analogous means, as indicated in Fig. l. Antennas according to the present invention are particularly weli suited for feeding through coaxial lines and for tuning as above described. The tuning and feeding lines may also serve as mechanicai antenna structure as willabe de scribed below more in detail. it is thus possiblewto provide a good impedance match with comparatively very simple and rugged means which permit exact tuning adjustment in the shop upon assembly of the antenna, eliminating all work of that type on location.

Fig. 3 shows'the horizontal radiation pattern of frames according to. Figs. i and 2, that is of single frame or wave guide section antennas. It will be noted thatthe azimuth pattern of the single frame antenna has a 90 degree half power angle. Fig. 4 shows the vertical radiation pattern. If the feed line connected sides of the antenna are approximately equal to one wave length, the halfpower angle in this plane is approximately 40 degrees.

Two or morewave guide sections of this type can be combined to form arrays in the general manner indicated in Fig. 5 with frames Fa, Fb of any desirable shape and spatial correlation. By suitably selecting the mutual spatial arrangement of the individual frames, and by ad justing the phase relation of the waves on the respective frames as indicated by impedances Z1, Z2 and Z3, any desired radition pattern can be obtained and its orientation and form as well as its strength regulated.

Specific instances of multi-frame units are indicated in Figs. 6, 7 and 8. Fig. 6 shows two frames F1, and F2 in parallel planes, with waves at different phases thereon, as indicated by phase shifting line loop 71. Fig. 7 shows a double bay antenna with two stacked co-planar single frame or loop units F3 and F4 fed through a double wire line. Fig. 8 shows a single bay section double frame or loop unit, with orthogonally intersecting frames or loops F5 and F6 and fed with appropriate phase difference by means of loop 72. As indicated in Fig. 8, frames F5 and F6 may be of identical shape and size with their shorter sides crossing at right angles forming an axially symmetric structure. Double frame units of this type furnish a practically perfect circular radiation pattern, as indicated in Fig. 9, if fed degrees out of phase, and crossing as exactly as possible at right angles. In Fig. 9, q indicates the radiation pattern of a single wave guide section as shown in Fig. .3, whereas Q indicates the total nondirectional pattern. If the two. frames are unequal but the array is symmetrical to the respective frame planes, radiation patterns similar to that indicated in dotted lines at Qe of Fig. 9 can be obtained, that is, elliptical radiation patterns. It will be evident that these frames and arrays can be used in any desired position. For example if axis z is vertical, the pattern according to Fig. 3 will be the vertical radiation pattern and that according to Fig. 4 the horizontal pattern.

As mentioned before, antennas according to the present invention lend themselves particularly well to fabrication from structural metal members. Such a practical embodiment will now be described more in detail with reference to Figs. lla to 13.

Figs. 11a to 12 show four rolled channel columns 81, 82, 83, and 84 which are welded to top and bottonrspacer plates 86 and 87 respectively. The bottom or base plate 87 may be fastenedto a structural base in any suitable and convenient manner providing proper insulation and mechanical support. The plates 86 and 87 serve from the electrical point of view as the upper and lower frame members indicated with corresponding numerals in Fig. 8 which similarly indicates the channel members. In other words one frame of the type of F5 of Fig. 8 is constituted by channel 82, top plate 86, channel 84 and bottom plate 87, whereas the other frame F6 is made up of channel 81,.plate 86, channel 83 and bottom plate 87. Energy is supplied through acoaxial conductor 90 which runs, through a T fitting 96,.along channel 32 to the center thereof Where it leads through a T fitting 93 into an opening of the channel, as indicated in the right hand half of Fig. 12. The outer conductor 91 is clamped or welded to the channel and the inner conductor 92 secured therewithin by suitable conventional means. The inner conductor 92 leads through the opening in channel 82 to the opposite channel 84, crossing the corresponding inner conductor of the other frame by way of semicircular clbow 100, and enters channelr84- through an opening from which it descends within a tubular outer conductor 94 which joins the channel opening by way of an elbow 94a. This last mentioned structure constitutes a series tuning stub similar to that described with reference to element s of Fig. 2. The outer conductor 91 continues on channel 82 upwardly'from the above-mentioned T piece 93, as indicated at 95, forming with its inner conductor a parallel tuning stub similar to p of Fig. 2. By way of elbows 96 and 97, a loop 98 branches from line 90, which loop provides a 90 degree phase shift between the two frames. From elbow 97, a coaxial line 99 ascends channel 81, leading to a T fitting 101 where'it branches into a parallel tuning stub 102 and, penetrating channel 81 as above described for channel 82, crosses over to channel 83 into elbow 103 whence it descends as series stub 104. The stubs are provided with tuning plugs that are suitably shifted when the antenna is tuned in the shop and then brazed, welded or otherwise electrically connected to inner and outer conductors, whereupon the latter may be cut off above the plug.

Fig. 12 shows that conical end pieces 111 may be pro vided which, forming an electrical continuation of the outer conductors of the coaxial, surround the inner conductors on the inside of the channels at the above-mentioned windows for the wires crossing at 100. These cones arev particularly desirable for purposes of broad band sending, but may be omitted as shown in Fig. 13.

As mentioned above, the outer conductors of the co axials may be fastened to the channels in any convenient way, for example by welding as shown at 112 in Fig. 12, or by means of clamps as shown at 115 in Fig. 13.

It will be evident that instead of feeding this section by means of a coaxial line, it can be supplied with a twowire line as shown in Fig. 8.

' As mentioned above, the mechanical structure of a co axial feedline may be used as mechanical component as well as electrical element of a frame. Such constructions will now be described with reference to Figs. 14 to 18.

In Fig. 14 a three bay section directional antenna is shown, whose three frames are fabricated from tubes fastened to plates 121, 122, 123 and 124. The intermediate plates 122 and 123 may be split for convenient assembly and erection manipulation as indicated by two separate plates 123a and 123b, which are joined by screwing or welding after the respective frames have been assembled in the shop. The longer sides of the frames are formed by tubes 131, 132 which are of the same shape for each frame, with the exception of the lowermost frame which has preferably one tube 133 that penetrates and extends below plate 124, forming the feed line to be described below. The tubes may lead through openings of the plates as shown at plate 123, or the tubes may be interrupted with the plates being solid excepting holes for wires 135 as shown for plate 122.

These wires 135 constitute, together with the tubes which also form the frames proper, coaxial lines for feeding and tuning the antenna. The coaxial feed line is connected to the frame at plate 124 as described above. The inner conductor 135 has branches 136 which lead through three openings in the outer conductor across the frame into similar openings of the opposite tubes 131 wherein they extend into open or closed series reactance tuning stubs 137, fastened to the tubes by means of plugs 138 which are made of metal if the respective stub is short circuited or of insulating material if it is open. The main feed line 135, 133 extends into a parallel reactance tuning stub 139 with plug 140 of the type above described for the series tuning stubs.

An antenna array ofthis type has a directional horizontal radiation pattern similar to that shown in Fig. 3, and a considerably compressed vertical radiation pattern of the configuration shown in Fig. 15.

Nondirectional single or mum-section antenna arrays can be put together from frames such as shown in Fig. 14, and such a construction is shown in Fig. 16. In this figure, base plate 141 and intermediate plates 142 as well as a top plate (not shown) may be cross shaped as shown in Fig. 16, or round as indicated with a dot and dash line 1410!. The feeding and tuning construction is analogous to that shown in Fig. 14. A phase shifting loop 145 is added, and the inner conductors connecting opposite tubular. frame members across each other as indicated at 150 of Fig. 16. Fig. 16 shows series react ance tuning stubs at 148 and 149, but the parallel tuning instrumentalities are not shown since they are located in an upper section into which lead the tubes 131, 133, 141 and 143 and inner conductors and shown broken off in this figure.

The radiation pattern of such an array is similar to that of Fig. 9 and, if several stacked bay sections are used the vertical radiation pattern is compressed as indicated in Fig. 15.

It will be evident that single directional wave guide sections of this type can be stacked in the manner indicated in Fig. 7, and that on the other hand single wave guide sections can be used.

Instead of feeding a tubular frame by way of one of the frame sides, a centrally located line may be used for that purpose, as shown in Figs. 17 and 18.

Fig. 17 shows a single frame bay section with frame F7 which is supported on the outer conductor 161 of a coaxial line whose inner conductor is shown at 162. The frame sides 163 and 164 carry stubs 165 and 166. One side 163 of the frame is connected to the inner conductor 162 through openings in conductor 161 and stub 165, whereas the other side of the frame, namely 164, is connected to the outer conductor through an opening in its stub 166. Stub 165 and 166 constitute series tuning irnpedances, whereas a plug 167 connecting outer conductor 161 with inner conductor 162, extended beyond the branch point 170, constitutes a parallel tuning impedance.

The antenna shown in Fig. 18 is of the unidirectional type, but otherwise quite similar to that discussed with reference to Fig. 17. The only difference is that the outer frame members 171, 1'72, 173 and 174 of the respective frames are tubular through their entire length. These sides are connected to the central supporting tube by cross members such as Wires 177 and 173 corresponding to plates 141, 142 of Fig. 16. The frames are connected with the outer conductor 181 by means of wires 182 and with the inner conductor 185 by wires 186, which wires terminate in tuning stubs 18% and 139. The feeding coaxial 181, 185 itself terminates in a parallel tuning stub 190.

As previously mentioned, the frames according to the invention can be combined in various types of coplanar arrays. Some possibilities of this type are indicated in Figs. 19 to 22. Figs. 19 and 20 show a practical manner of assembling several frames of the type shown in Fig. 7 to form multiple coplanar arrays with common base and top plates 191, 192 which, together with the frame members 193, 194 form the individual frames 195. Fig. 21 indicates the compressed radiation pattern on axis x for a three section array of this type. These figures show the upper and lowermost sections partly broken away.

Coplanar arrays of the type as shown in Figs. 19 to 21 can be combined to form multi-planar multi-sectio-n arrays of the type shown in Fig. 22 which in view of the above description needs no further explanation.

Wave guide or frame antennas according to the invention can be used in any position, for example horizontally extending and vertically polarized, as indicated in Fig. 23. The antenna schematically shown in that figure cor responds to the nondirectional system according to Fig. 8 as indicated by corresponding numerals. The radiation pattern in a vertical plane of this antenna is that shown in Fig. 9 and is of course the same as the horizontal pattern for the antenna according to Fig. 8.

Single frame antennas of the horizontal type according to Fig. 26 are particularly useful for mounting on vehicles. For that purpose the body or fuselage of the vehicle such as an automobile or airplane can be utilized to form a part of the antenna frame. By way of example, Fig. 24 to 26 show such an antenna as applied to an omnibus. In these figures a bail 201 is mechanically and electrically connected to the metallic roof structure 202 of the vehicle and connected to a suitable housing 203 for the trans mitter, by means of a coaxial line with outer conductor 205 and inner conductor 266. Figs. and 26 show the vertical and horizontal radiation patterns respectively.

As mentioned above, antennas according to the present invention lend themselves particularly Well for combination into multi-bay section nondirectional arrays with high gain and compressed vertical radiation pattern, constructed with a minimum amount of mechanically but not electrically effective materials, in other words havingoptimum efficiency so far as the ratio of mechanically necessary and electrically indispensable material is concerned, requiring at the same time, as compared with conventional constructions, a minimum of electrically indispensable material. Figs. 27 to 31 illustrate an embodiment of this type.

Figs. 27 to 29 show a nondirectional four section antenna fabricated from wide flanged I-members, channel members and rolled plates. For mechanical as well as esthetic reasons the width of the respective bay sections decreases with increasing height. The antenna is supplied through a coaxial line in the manner described above with reference to Figs. 9 to 13 in order to simplify these figures, only part of the supply system is shown therein, Figs. and 31 supplementing this showing.

The three lower bay sections 210, 221i, 230 are made up from plate crosses 211, 221, 231, and 241 to which are welded I-members indicated at 212, 222 and 232. The uppermost section is 24% formed from channels 242 which are welded to cross plates 241 and 251. It will be appreciated that these sections, as those previously described, are considerably higher than wide, as indicated in Fig. 27 by breaks on either side of the cross feeding inner conductors. These cross feed conductors are indicated at 215 and 216 for the lowest section 210 only. The corresponding outer conductors may be welded to the I-members, terminating at openings therein in the manner shown in Fig. 13. Instead, the coaxial conductors may be supported by mechanicalclamps joined to the frames as likewise shown in Fig. 13; they may be surrounded, on the inside of the frames, by cones according to Fig. 12.

Two modes of feeding are indicated in Figs. 30 and 31. According to Fig- 30, all frames. in the x, y plane are fed directly from the line 265 and all frames in the y, 2 plane are fed through one phase shifting loop or similar impedance device indicated at 260, According to Fig. 31, two loops 261 and 262 are provided which branch in parallel from line 267. It will be understood that Figs. 30 and 31 indicate the feed lines. as terminating at respective sides of the frames, do not differentiate betwcen the two conductors such as outer and inner coaxial conductor, and do not show the cross connections such as 215 and 216 of Fig. 27, with the tuning stubs. These stubs are however indicated in Fig. 27 for example at 219 as an open stub without coaxial. It will further be noted that Fig. 27 does not indicate the main and branch feed lines diagrammatically shown at 265 and 266 of Fig. 30 and 267, 263 and 269 of Fig. 31. Where as Fig. 30 indicates all eight wave guide frames, Fig. 31 shows only the two uppermost frames.

In order to increase the mechanical strength of antennas of this type, end plates. or blocks may be used for each bay section instead of the process shown in Figs. 27, 28 and 29 to which plates the structural shapes forming the longer sides of the wave guide sections are secured by means of flanges, bosses or analogous configurations of the end plates. Such constructions are described in detail hereinbelow.

The operation of antennas of this type needs little enplanation. The bay sections are adjusted for proper phase displacement of the respective wave guide sections, and they are adjusted for the frequency to be transmitted by means of the tuning stubs. These, adjustments are made permanent by appropriate fixation of the respective components, such as screwing or otherwise fastening the tuning plugs to their respective conductors.

These operations can beperformed in the shop with the aid of laboratory precision equipment and if the antenna in question has several bay sections these can then be separated, separately shipped and erected and reassembled at the location of use. Experience has shown that the shop adjustment and tuning is not disturbed by such dismantling and reassembly.

Fig. 32 indicates possibilities, very-valuable in actual practice, for tuning an antenna of the present type which is fed through a coaxial line 55, 56 running along one side of the frame P which is otherwise quite similar to those of Figs. 1 and 2. In this figure, s represents a series reactance, and p a parallel reactance, which in this instance take the form of stubs. The stubs may be short-circuited, that is, inner conductors 62 and64 may be metallically connected to outer conductors 63 and 65 by metal plugs 67, 68 or the stubs may be open ended in which case the plugs are of insulating material. Antennas according to the present invention are particularly well suited for feeding through coaxial'lines and for tuning as above described. It was found that in many instances series reactances such as shown at s are sufiicient in which case the inner conductor 56 is 'bent to lead directly through opening a, outer conductor b forming an elbow at that point in the manner shown for stub s.

As mentioned above, two or more wave guide sections.

of this type can be combined to form arrays and by suitably selecting the mutual spatial arrangement of the individual frames, and by adjusting the phase relation of the waves on the respective frames, any desired radiation pattern can be obtained and its orientation and form as well as its strength regulated. Fig. 8 shows a single bay section double frame unit, with intersecting frames F5, F6 and fed with appropriate phase difference by means of loop 72. As indicated in Fig. 8, framesFS and F6 may be of identical shape and size with their shorter sides crossing at right angles forming an axially symmetric structure. Double frame bay sectionsof this type furnish a practically perfect circular radiation patternas described above with reference to Fig. 9.

As mentioned before antennas according, to the present.

invention lend themselves particularly well. to fabrication from structural metalshapes. Sucha practical. embodiment is the subject matter of the present invention and will nowbedescribed more indetail.

As shown in Figs. 33, 34 and 35, four channelehapes 401, 402, 4%, and 404 for exampleofsteeLonaluminum and longer than one-half of the wave length to be-transmitted, arefastened to,two.end pieces .406, 407 of similar material. The. platesdtiand 407 serve from the electrical pointof view as the upper and lower frame members indicated with corresponding numeralsin-Fig.-8 which similarly indicates the channel members. In other words, one frameof the type of P5 of Fig. 8- is constituted by channel 4&1, top plate 406, channel 403 and bottom plate 407, whereas the other frame F6 is made up of channel 402, plate 406, channel 404 and bottom plate 407. Figs. 33 to 35 show cast metal end pieces having four recessed bosses 411, connected by plate portions 412 andribs 415. The recesses 416' of bosses 411 conform to the cross section of the channel members. The end pieces are covered by circular plates 418, 419 against which the channels abut as clearly shown inFig. 8. The channels arebolted-to the recesses of bosses 411 of the endpiecesas shown at 421, and the plates 418, 419 are bolted to the end pieces as shown at 422. Bolts 424 are provided to fasten the antenna to a supporting structure or foundation or, it several bay sections are used, to bolt these sections together.

Energy is supplied to and distributed between the two individual antenna frames by means of coaxial lines. Figs. 33 and 34 show at 430 a connection to a feed line, with an outer tubular conductor 431 and an inner'conductor 432. The supply. line branches at a T-fitting 433 andleads on one side at 434 to a branch 435 rising on channel 402, and fastened to that channel by means of clamps 436 (Figs. 33 and 34). This line ends in a series tuning impedance element 438, of the type described above with reference to Fig. 31. As shown in Figs. 33 and 34, and schematically indicated in the upper portion of Fig. 39, the inner conductor of the coaxial line branches off towards the center of the frame formed by channels 402 and 404 and leads to the opposite side of the frame. This cross connection 441 (Fig. leads through an opening to an elbow fitting 446 on the outside of channel 404 whence it terminates in a series reactance tuning stub 439, which is quite similar to parallel reactance stub 438.

A second branch 454 leads from juncture 430 around the base block 407 to branch feed line 455 which ascends on channel 401 to a T-piece 456 which is quite similar to the above-mentioned T-piece 433. The vertical ex-.

tension of line 455 beyond T-piece 456 constitutes another parallel reactance tuning stub 458' similar to members 438 and 439. From T-piece 456 a cross conductor 461 extends to the other side of the frame, penetrates channel 403 and from an elbow fitting outside the channel 403 extends upwardly, terminating into series tuning stub 459.

The connections 441 and 461 cross with semicircular bends 440 (Fig. 34) and are preferably inclosed in a radome 460 a practical embodiment of which will be described below with particular reference to Fig. 38.

It will be noted that branch line 454 is longer than branch 434; the difference in length between these two lines supplies a phase shifting impedance, establishing a phase difference of 90 between the waves on frames 401-403 and 402-404, respectively. The juncture 430 can be shifted along the straight section of line 434--454, thus permitting exact adjustment of the phase difference in order to obtain a practically perfect circular radiation pattern such as shown in Fig. 9.

It will further be noted that the radome 460 is arranged in the Zone discussed above with reference to regions a, b of Fig. 2. Since the impedance across the frame sides is low in this zone accumulation of ice or snow on the radome have little if any detrimental effect.

In order to permit increased radiation and to compress the x--y radiation pattern, several sections of the abovedescribed type may be stacked. upon each other; a typical two-section antenna of this type Will now be described with reference to Figs. 36 to 41.

The individual bay section structure proper is quite similar to that described above with reference to Figs. 33 to 35. Two such sections are bolted together with the screws indicated at 424 of Fig. 35.

The energy supply arrangement is schematically indicated in Fig. 39 wherein single lines indicate the antenna sections proper, and double lines the coaxial feed lines and tuning stubs; these are denoted with identical numbers in Figs. 36 and 39.

The mounting of the feed and tuning lines of the two sections antenna according to Fig. 36 will be better understood with reference to Fig. 39 as follows.

The main supply line 500 is clamped to channel 501 by means of clamps of the type shown in Fig. 37 and to be described more in detail below. The main supply leads through branch lines 511 and 512 into loops 515a, 5151; (collectively indicated as 515) and 516a, 516b, respectively. Referring first to the lower bay section, loop 515 continues downwardly along channels 503 and 507, with feed lines 523 and 527, ending in parallel reactance tuning stubs 533 and 537 respectively. A- cross connection 525 branches between 527 and 537 and'leads to a series tuning stub 535 on channel 505. A similar cross connection 521, branches from a T-fitting between 523 and 533, leads to a tuning stub 531 on channel501. The feeding, connecting and tuning elements of theupper bay section are arranged quite similarly as will now be clear from the corresponding numerals applied to Figs. 36 and 39 without further explanation.

Referring now to Fig. 37, it will be noted that clamps of the type shown in that figure can be used for attaching main as well as branch feed lines to the channel members. These clamps consist of clamp blocks 551 bolted to the channels at 552 and having a semicylindrical recess 553 for the branch line tubing. If such branch line tubing alone is clamped to a channel such as shown at 436 of Figs. 34 and 36, a straight clamp bar as shown at 556 of these figures is used. The larger diameter main supply tubing is clamped to the branch line tubing by means of clamp jaws 557 and 558 (Figs. 36 and 37) which are screwed or otherwise fastened to the block 551 at 561 and forced together by bolts 562 in order to establish firm electrical and mechanical contact between channels, clamp block and tubing. If large diameter tubing alone has to be-attached to a channel as for example at 565 of Fig. 36,

is inserted between clamp block and large diameter tubing.

The cross connection construction such as indicated at 440, 441, 461 of Fig. 34 and 521, 525 and 522, 526 of Fig. 39 will now be described. This has the purpose of mechanically supporting and protecting the cross connections and of establishing the proper electrical correlation between the antenna proper and these connections.

It is standard practice to keep short wave feed lines of the type herein described dry by means of filling them. with an inert gas such as nitrogen, or dry oil under pressure thus preventing the seeping in and condensing of water vapor. Figs. 13, 15 and 16 show such a construction which was found to be well suited for antennas of the type according to the invention.

As shown in Fig. 40 the inner conductors of the coaxial line are supported in conventional manner within the outer tubular conductor, by means of beads 571. The inner conductors are assembled by means of suitable elbow and T-pieces and connectors such as shown in Fig. 41

with spring prongs 575 screwed into one end 576 of an inner conductor and making contact within hole 577 of conductor 578. The outer conductors are assembled by means of flanges 581 and 582 brazed to the tubes and bolted together with sealing gaskets therebetween in order to assure a pressure tight connection. Fig. 40 shows this construction as applied to the loops 515, 516 (Fig. 39) and analogously to the other branches of the feed lines and to the tuning stubs.

Fig. 38 indicates a branch line with outer conductor 591 and inner conductor 592. An outer tube 593 and an inner conductor 594 branch from this feed line, with tube 593 fitting the opening 440 of the channel. A hollow metal cone 601 is fastened to the channel for example by screws 602. This cone has a thread 603 at its outer end and is slipped over tube 593. A gasket 605 sits at the ends of tube 593 and cone 601 and on this gasket rests an insulator 606 which is on its outer face held by a shoulder 607 of the inner conductor, with gasket 608. The inner conductor is threaded and holds insulator 606 between shoulder 607 and nut 611. A flanged nut 612 presses the insulator against the face of cone 601.

The inner conductors cross each other with semicircular deviations 609 and proceed to a similar supporting and insulating construction on the inside of the opposite channel. The entire crossing assembly is protected by a circular radome of the general shape shown in Figs. 33 and 34. It consists essentially of an upper half 701 and lower half 702 of insulating material, screwed together at 703 (Figs. 33 and 34) and holding the cones 601 with screws 704. In order to establish communication 'betweenthe' space enclosed within the outer conductors on either side of the crossing, the inner conductors which form the crossings are tubular and'have openings on either side of the crossing, as indicated at 705 of Figs. 38 and 41.

Instead of using cast (for example cast aluminum) end blocks as shown in Figs. 33 to 36, welded end pieces such as shown in Figs. 40 and 42 may be used. In these figures, 719 is a base ring to which are Welded fiange plates 721, gusset plates 722 and cross plates 723, to which, as shown in Fig. 40, the channels, for example Sill, 584, 506 and 508 are welded.

Instead of using a phase shifting loop for each bay section as shown in Figs. 36 and 39, a single loop may be used for feeding all coplanar frames of two or more bay sections. Such an embodiment is shown in Figs. 43, 44 and 45.

In Figure 43 numeral 690 denotes the main energy supply line corresponding to line 500 of Figs. 36, 39 and 40. A branch 611 leads from 600 towards a T fixture 612 from which coaxial lines of smaller diameter numbered 627 and 628 lead to coplanar frame sides 505 and 506, respectively. Another branch of the main supply line numbered 613 forms loop 614 and continues as main supply branch 615 which divides at 617 into conductors 623 and 624- leading to coplanar frame sides 501 and 502. In the manner described above with reference to Figs. 36 and 39, cross connections 621, 625 and 622, 626 lead to the respective opposite sides 593, 507 and 504, 508 of the frames where they terminate in series tuning stubs 631, 635, and 632, 636, respectively.

Figs. 44 and 45 show in detail the practical construc tion of a coaxial supply system of this type, with elbow fittings 651, suitably flanged together as clearly shown in Fig. 45, reducers 612 which also serve as T fittings, and main supply fitting 6il1 for connecting the main supply line to its branches 611 and 612.

It will be observed that the antenna with several bay sections according to Figs. 43, 44 and 45 is equipped with series tuning stubs only; this exemplifies a construction which is in many instances quite satisfactory although in other instances both parallel and series tuning inductances may be employed.

The operation of antennas of this type needs little explanation. "Hie bay sections are adjusted for essentially exact 90 phase displacement of the respective wave guide sections, and they are adjusted for the frequency to be transmitted by means of the tuning stubs. These adjustments are made permanent by appropriate fixation of the respective components, such as screwing or otherwise fastening the tuning plugs to their respective conductors. These operations can be performed in the shop with the aid of laboratory precision equipment and if the antenna in question has several bay sections these can then be separated, separately shipped and erected and reassembled at the location of use. Experionce has shown that the shop adjustment and tuning is not disturbed by such dismantling and reassembly.

As previously mentioned antennas of this type are mechanically very strong and can be used as supporting structures for example of heavy beacon lights or other antennas.

Although only a two bay section antenna is herein described in detail it should be understood that any suitable number of such sections can be combined by joining the base blocks ,or plates of respective sections and by appropriately extending the feeding and phase control system as above described. As likewise described in that application, the bay sections may be of different size, for example decreasing in width of the upper, bay sections of a multi-sectic-n array.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims.

i claim:

I. A wave radiator comprising two antenna-loop sections of conductive material of approximately equal rectangular-shape and size, the sections intersecting along theirshorter sides symmetrically at approximately right 15 angles, and a transmission line having two conductor elements, a branch of said feed line leading to approximately opposite regions of respective longer sides of one section, and a second branch of said line leading in parallel to opposite regions of respective longer sides of the other section, and phase-shift-producing means connected with said branches for defining with said section; a phaseshift of approximately degrees between the waves on the respective sections.

2. A wave radiator comprising two metallic antenna frame members of approximately equal rectangular shape and size, the members intersecting with their shorter sides; and a system supplying radio frequency energy comprising two exciting means one extending substatitially parallel to the shorter sides of each frame member to feed the respective frames with said plane of polarization approximately perpendicular to the longer sides of the frames, said supply system including a branched feed line having two conductor elements, the conductors of one branch of said feed line leading to approximately opposite regions of respective nonintersecting longer sides of one frame member and the conductors of a second branch of said line leading to approximately opposite regions of respective nonintersecting longer sides of the other frame member, the last-named conductors crossing between said regions; whereby the frames emit a resultant electromagnetic wave which is polarized ap proximately perpendicular to said longer sides, and the impedance across said regions is comparatively low so that bridging of the regions by extraneous material is of comparatively little consequence.

3. A wave radiator comprising two antennadoop sections of conductive material of approximately equal rectangular shape and size, the sections intersecting symmetrically at substantially right angles, and a branched feed line having two conductive elements, the conductors of one branch of said feed line leading to substantially opposite regions of respective nonintersecting sides of one section and the conductors of a second branch of said line leading to substantially opposite regions of respective nonintersecting sides of the other section, and phaseshift-producing means connected with said branches for defining with said sections a phase shift of substantially 90 between the Waves of the respective sections.

4. A nondirectional wave radiator comprising two metallic spacer plates each having four symmetrical faces at the centers of sides of a polygon inscribed within the respective plate, four parallel metal channels fastened with their ends to respective faces of the plates to define with the plates two substantially similar rectangular frames symmetrically intersecting at right angles with the channels forming the longer sides of the frames; an energy supplying coaxial line leading towards the center of one of said channels with its outer conductor terminating thereon and with its inner conductor leading through an opening in said channel to the opposite channel where it terminates; and a second coaxial line branching from said line forming a phase shifting circuit element and leading towards the center of a third channel with its outer conductor terminating thereon and with its inner conductor leading through an opening in said third channel to the opposite fourth channel where it terminates.

5. A nondirectional wave radiator comprising two metallic spacer blocks each having four symmetrical faces at the centers of sides of a polygon inscribed within the respective plate, four parallel metal channels having webs and flanges opening outwardly and fastened at their ends with their webs to respective faces of the blocks to define with the blocks two substantially similar rectangular frames symmetrically intersecting at right angles with the channels forming the longer and the blocks forming the shorter sides of the frames; an energy supplying coaxial line leading towards an end and along approximately one-half of the length of one channel towards the center thereof with its outer conductor fastened to the channel and terminating thereon, and with itsinner conductor leading through an opening in said channel to the opposite channel where it terminates; anda second coaxial line branching from said Supplying line, forming first a 90 phase shifting loop and then leading towards the adjacent end and along approximately one-half of the length of a third channel towards the center thereof with its outer conductor fastened to the third channel and terminating thereon and with its inner conductor leading through an opening in said third channel to the opposite fourth channel where it terminates.

6. A wave radiator comprising a plurality of bay sections, each section including four flanged structural metal shapes connected with their. ends to metallic blocks and defining two similar rectangular loop sections symmetritically intersecting at right angles at the blocks, respective structural shapes of adjacent baysections being aligned and the blocks of adjacent bay sections being joined; a coaxial transmission line approaching an end of one of the structural shapes of one of said sections and running along two alignedshapes'withthe outer component of the line mechanically and electrically connected thereto, the inner component leading freely through the approximate centers of the aligned structural, shapes carrying its line to the opposite shapes of therespective frames to which shapes it is electrically connected; a branch of the transmission line of a length defining a 90 phase shift leading from said line to the end of the adjacent aligned structural shapes of the intersecting loop sections and running along the said adjacent shapes with the outer component mechanically and electrically connected thereto, the inner component leading freely through the approximate centers of the aligned structural shapes carrying its line to its opposite shapes of the respective frames to which shapes it is electrically connected; and coaxial tuning stubs at the ends of the inner components of said lines with the outer components of the stubs connected to the respective shapes and inner components of the stubs connected to said ends.

7. A wave radiator comprising two antenna-loop sections of conductive material being of substantially equal rectangular shape and size, the sections intersecting with their shorter sides symmetrically at substantially right angles; and a system supplying radio frequency energy with two fields of given orientation with the same plane of polarization and 90 phase displacement placed to feed the respective sections with said plane of polarization substantially perpendicular to the longer sides of the sections, said supply system including a branched feed line having two conductor elements, the conductors of one branch of said feed line leading to substantially opposite regions of respective non-intersecting longer sides of one section and the conductors of a second branch of said line leading to substantially opposite regions of respective nonintersecting longer sides of the other section, and said branches defining with said sections a phase shift of approximately 90 between the waves on the respective members.

8. A wave radiator comprising two rectangular sub stantially congruent antenna-loop sections made of conductive material each section having two parallel longer sides and two shorter sides, and the sections crossing symmetrically at substantially right angles; a feeding network including a coaxial main line branching into two secondary lines, the outer conductor of each secondary line terminating substantially at the midpoint of a longer side of a respective section and the respective inner conductor leading past the respective side and terminating substantially at the midpoint of the respective opposite sides, said inner conductors crossing between said midpoints; a housing member electrically insulated from said conductors and arranged between said longer sides to protect said inner conductors; and phase shifting impedance means included in one of said secondary lines.

9. A pair of substantially symmetrical planar closed transmitting antennasloopsdisposed in substantially orthogonal planes, each loop being of length greater than 'its 'width, and a feed system for supplying radio-frequency energy to each'loophaving exciting means disposed substantially in the plane of and within the loop and means for supporting the exciting means to extend substantially parallel to the width ofthe loop and terminating upon, the

v the antenna and the width is less than substantially the said half-wavelength.

11. Aplurality of co-planar in-line transmitting antenna loops each of length greater thanits widthand a feed system for supplying radio-frequency energy to each loophavingexciting means disposed substantially H in the pane, ofand 'within theloop and meansfor supporting the excitin'gmeans to extend substantially parallel to the width of the loop thereby to feed the 'loopwith radio-frequency energy the plane of polarization of the field of which is substantially perpendicular to the length of the loop. I

12. An antenna as claimed in claim 11 and in which the exciting means terminates upon at least one of the longer sides of each said loop.

13. An antenna as claimed in claim 11 and in which the exciting means terminates upon each loop at a point intermediate its length.

14. An antenna as claimed in claim 11 and in which each loop is of substantially rectangular contour and the exciting means terminates upon the loop at a point intermediate its length.

15. A radiator as claimed in claim 11 and in which the longer sides of each loop comprise two tubular conductors and the exciting means terminates upon the loop at a point along one of the tubular conductors.

16. A pair of substantially symmetrical planar closed transmitting antenna loops of substantially rectangular contour disposed in substantially orthogonal planes, each loop being of length greater than its width, and a feed system for supplying radio-frequency energy to each loop having exciting means disposed substantially in the plane of and within the loop and means for supporting the exciting means to extend substantially parallel to the width of the loop and terminating upon the longer sides thereof intermediate the same, thereby to feed each loop with radio-frequency energy the plane of polarization of the field of which is substantially perpendicular to the length of the loop.

17. A pair of substantially symmetrical planar closed transmitting antenna loops of substantially rectangular contour disposed in substantially orthogonal planes, each loop being of length substantially equal to or greater than the half-wavelength of the radio-frequency energy transmitted by the antenna and of width less than substantially the said half-wavelength, and a feed system for supplying radio-frequency energy to each loop having exciting means disposed substantially in the plane of and within the loop and means for supporting the exciting means to extend substantially parallel to the width of the loop and terminating upon the longer sides thereof intermediate the same, thereby to feed each loop with radio-frequency energy the plane of polarization of the field of which is substantially perpendicular to the length of the loop.

18. A transmitting antenna as claimed in claim 9 and in which the longer sides of the loops are two tubularcolumns.

19. A transmitting antenna as claimed in claim 17 and in which the longer sidesiof the loops are two tubular columns.

20. An'antenna as'claimed 'in claim 11 andiin'which each said loop is of substantiallyirectangular .cont'our.

21. An antenna as claimed in claim 11 and in which the longer'sides of each said-loop comprise tubular conductorsand the shorter sidesplanar conductors.

22. Anantenna as claimed inclaim l1 and in which the Iength'of eachisaid loop is substantially equal to or greater than the half-wavelength'of the radio-frequency energy transmitted bythe antenna and the width isless than substantially the saidhalf-wavelength.

23. An antenna as claimed .in claim' 22 and in which the longer sides of the said loops comprise t'ubular columns.

24. "A'pair of pluralities dfantenna loopsas claimed in claim 11*and'in whichthe loops of each pair are "disposed"substantially orthogonally to the loops of the other pair.

25."Amantenna'as"claimed in claim 24 and in which thelongersides of'the said loops comprise tubular columns.

26. Anantenna asclaimed inclaim' 11 and in which the longer sides of 'the said loops comprise tubular columns.

.253 References Cited inthe file of this patent :UNITED STATES PATENTS 2,082,812 worrall June-8, 1937 2,131,108 .Lindenblad '3Sept. 27, 1938 2,210,491 Lewis --AugJ 6, 1940 2,283,897 Alford May 26, 1942 2,286,179 Lindenblad June '9, 1942 2,304,446 Eaton Dec.' 8, 1942 2,327,485 Alford Aug-.24, 1943 2,425,336 Mueller ---Aug. 12, 1947 2,438,987 Bailey "Apr. 6, 1948 1 2,511,931 Masters '-June'20, 1950 2,513,007 Darling June 27, 1950 FOREIGN 'PATENTS 519,350 Great Britain .:Mar. 21,1940

- OTHERREFERENCES 'Slot Aerials, D. A..Bell, WirelessWorld, February 1948, pages 57-58. (Copy in. Division 44.)

GreeneFM. AntennaaUses Waveguide Principle, page 38, FM and Television, July 1947, page'38. (COPy' in library.)

'IRE Standards on Antennas-and Waveguides: vDefini- 'tion of terms, 1953, Proceedings-ofthe-IRE, December 1953, page 1725.

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