US2699500A - Bidirectional antenna - Google Patents

Description

1955 M. D. ERCOLINO BIDIRECTIONAL ANTENNA 2 Sheets-Sheet 1 Filed Aug. 28, 1950 L INVENTOR MDLErcoZiflo s as m ATTORNEYS Jan. 11, 1955 M. D. ERCOLINO 2,699,500

BIDIRECTIONAL ANTENNA Filed Aug. 28, 1950 2 Sheets-Sheet 2 INVENTOR BY ,y z 3 ATTORNEYS United States Patent BIDIRECTIONAL ANTENNA Michael D. Ercolino, Wanamassa, N. J. Application August 28, 1950, Serial No. 181,876

2 Claims. (Cl. 250-3353) This invention relates to antenna systems and, more particularly, to a stacked array by-directional television antenna having vertically spaced interconnected transposed dipole elements formed as wire loops.

Heretofore it has been considered necessary to construct antennas of the stacked array type from relatively large cross section materials in order to attain resonance at a frequency adapted for high gain performance throughout all of the television channels. Such construction effects a relatively large and heavy assemblage of parts that presents many installation and maintenance problems. The conventional antenna of this type being relatively heavy requires that it be placed at a specific location where substantial support can be provided, and such construction may in many instances require the use of special guying facilities in order to provide adequate support. Due to the large cross-section of the elements used in the conventional antenna, a large surface area is presented with resultant high wind resistance loading which becomes exceptionally heavy under conditions of sleet and/ or ice. These factors as well other well known objectionable features of conventional antennas make their use highly undesirable in many known instances, particularly in areas subject to heavy sleet and high wind conditions.

Therefore, it is among the objects of this invention to provide an antenna array unusually light in weight and low in wind resistance.

A further object is to provide a television antenna having high gain performance throughout all of the present television channels.

A still further object is to provide a compact antenna capable of producing a uniform, bi-directional figure of 8 reception pattern over the presently assigned television frequency range of 542l6 mc./s.

For television receiving purposes, it is highly desirable that the antenna exhibit a substantially uniform reception pattern (in the horizontal plane) at all frequencies within the television range so that orientation of the antenna for maximum sensitivity (in this case broadside, or perpendicular to the plane of the antenna) for one or more stations will not simultaneously present a null or area of insensitivity to other signals of different frequencies originating from the same general direction.

The conventional all channel" antenna is generally dimensioned to resonate at the lowest frequency to be received, namely 54 mc./s. and near its resonant frequency, the antenna will exhibit a satisfactory bi-directional figure of 8 directional pattern. At the higher frequencies, i. e., atwavelengths which are appreciably shorter than the physical length of the dipole, the directivity pattern will degenerate (progressively with frequency) and Will exhibit patterns characterized by multiple lobes or areas of sensitivity, and corresponding nulls or troughs representing areas of lower or zero sensitivity. This has the disadvantage, in practice, of

increasing the difficulty of effecting satisfactory orientation, for optimum reception, particularly when it is desired to receive signals at more than one frequency originating from the same general direction. Moreover, the possibility of minimizing or eliminating multipath interference (commonly known as ghosts) is reduced because orientation of the antenna for satisfactory reception of the direct signal may also result in maximum reception of a reflected signal from a different angle. Furthermore, the presence of multiple lobes frequently result in excessive reception of extraneous electrical disturbances originating from many directions, to the degeneration of picture quality.

Various methods have been suggested or employed for correcting or preventing the afore-described non-uniformity of reception pattern. They involve greater material expenditures, antenna elaboration and ditficulty of manufacture than the antenna of this invention. Moreover, some are characterized by lower sensitivity, par ticularly at the higher frequencies.

I have found that by resonating the individual antennas at approximately 92 mc./s., a substantially uniform directivity pattern can be maintained over the entire frequency range of 54-216 mc./s. Individually, these antennas are appreciably less sensitive from 54-88 mc./ s. than a dipole imensioned to resonate at 54 mc./s. would be over the same frequency range. Equivalent sensitivity is restored however, by vertically arraying them as described hereinafter, while at the same time the desired directivity pattern is retained.

Another object is to provide an antenna construction that is quick and easy to assemble and install for either outdoor or indoor use.

Other objects and features of the present invention will become apparent from the following description when read in conjunction with the drawings, and the invention consists in the novel form, combination and arrangements of parts herein described in detail, shown in the drawings and claimed in the appended claims.

In the drawings, wherein like reference characters refer to like parts in the different views:

Figure l is a front elevational view of the antenna of this invention.

Figure 2 is an enlarged detailed elevation of the terminal block.

Figure 3 is an enlarged detailed section taken on line 3-3 of Figure 1.

Figure 4 is a section taken on line 4-4 of Figure 3.

Figure 5 is a section taken on line 55 of Figure 3.

Figure 6 is an enlarged detail section taken on line 6-6 of Figure 1.

Figure 7 shows a modified form of mounting.

Referring now in detail to the drawings, Figure 1 shows the antenna 10 of this invention assembled and mounted for outdoor use, supported in a conventional manner on a suitable support such as pipe 11. The antenna 10 is provided with a mast 12, or vertical member to which the individual bays or dipoles 13 and 14 are fixed in vertically spaced relationship. The mast 12 is preferably formed of aluminum tubing of relatively small diameter and is cut to a length sufiicient to provide a mounting area 15 at at least one end and an assembly area 16. Aluminum or aluminum alloy construction as to the mast 12 is preferred because of its high strength, light weight characteristics plus the fact that such ma terials are corrosion resistant; however, it will be appreciated that in certain instances it may be found desirable to use other materials.

The tube of mast 10 is left in its conventional round form in the mounting portion 15 but is flattened at spaced points in the assembly area 16 to provide fiat clamp areas 17 and 18. Areas 17 and 18 are formed to the same contour and so as to face in the same direction to provide for the attachment thereto of the dipole clamps 19 and 20 with suitable screw, or bolt, means as at 21. The spacing of the clamp areas 17 and 18 is determined by consideration of the electrical characteristics desired as hereinafter explained.

The round mounting area 15 is socketed and secured to the side of support 11 by suitable clamps 22 formed with a suitably channeled plate 23 (Fig. 6) and back plate 24 with suitable bolts 25 extending therebetween. In those instances where it is desirable to mount the antenna 10 indoors it can be readily secured to a rafter cross-beam 26 (Fig. 7) by use of the channeled plate 23 mounted thereon by suitable lag bolts, or screws 27. I find it preferable to leave the mounting area 15 round, not only to retain its inherent strength, but also to make the array ready of turning so that it can be easily oriented or disposed for best reception and minimum pickup of multi-path signals or ghosts at any given location.

contributing This versatility of mounting means, the lightness of weight, and the compactness of antenna allows for its ready mounting at the most desirable and inconspicuous location to be found about the users home such as adjacent a rear chimney, outside of a window, in the attic or in a similar air space'usually common to dwellings.

Each of the clamps 19 and 20 are formed with a rigid rectangular shaped base 28, as best illustrated in Figures 2, 3, and 4, composed of Bakelite, or similar insulating material to which a pair of oppositely disposed clamping devices 29 are attached. Each of the devices 29 are formed with a front plate 30 having a securing area 31 apertured as at 32 for securing to the face 33 of base 28 adjacent the side edges thereof as with bolt means 34. The front plates 30 are preferably rectangular in shape and are formed with a pair of divergent channels, or grooves, 35, that extend outwardly from adjacent aperture 32. The portion 36 of plates 30 that extends outwardly from area 31 ispreferably set at an angle to effect forward tilting of the dipole elements extended parallel thereto, as hereinafter explained. Attached to the back of each front plate 30 by suitable tightening screws 37 is a back plate 38 adapted to complete the clamp construction effected by these two plates 30 and 38. Back plates 38 are arranged to abuttingly clamp against the adjacent edge of the base plate 28 as at 39 which adds greatly to the rigidity of the clamp construction.

Carried by the clamps 19 and 20 and extending therefrom as spaced pairs of looped wires are antenna elements 40 formed as left and right top loops 41 and 42 and left and right bottom loops 43 and 44 respecitvely. The wire loops 41, 42, 43 and 44 that form the dipole elements consist of straight lengths of relatively thin wire, namely, /8 inch in diameter, cut to the desired lengths with their ends 45 inserted into divergent grooves 35 (Fig. 2). This construction allows the wire of each element 40 to assume a natural radius or bow, without danger of becoming kinked or unduly stressed. The wire of elements 40 is preferably an aluminum alloy such as Dural which I have found to have the degree of temper, hardness, elasticity, and durability desired, although I have secured fairly satisfactory results under favorable conditions with elements 40 formed of other conducting materials such as steel and stainless steel.

The top loops 41 and '42 are interconnected with the bottom loops 43 and '44 by a pair of transposition bars 46 and 47 formed of aluminum alloy or like conducting and corrosion resistant material. Bars '46 and 47 are arranged to form separated conductors for transposed connection of one of the top loops to one of the bottom loops. For instance, as shown in Figure l, the left top loop 41 is connected to the right bottom loop 44 by bar 46, and the right top loop 42 is connected to the left bottom loop 43 by bar 47. One of the bars 46 or 47 is formed with an angularly displaced mid portion 48 (Fig. 4) bent outwardly to provide a nonconducting air spacing between the two bars where they cross each other. The opposite ends 49 of each bar 46 and 47 are electrically connected to an adjacent loop by being secured to a suitable clamp bolt 34 as best illustrated in Fig. 4.

Disposed at adjacent ends of bars 46 and 47 and electrically connected thereto are a pair of terminals 50 (Figs. 1 and 2) for connection of a suitable transmission line.

The individual bays or dipoles 13 and 14 when formed of inch wires cut in 66 inch lengths and bent to their natural radius to form elements 40 approximately 30 inches in length and having a maximum loop width of approximately 10 inches are found to have a natural resonant frequency of 92 mc./s., at which frequency a quarter-wave length is 0.81 meter or about 33 inches,

while it is found that the complete array measured across terminals 50 is resonant at 76 mc./s., at which frequency a quarter-wave length is 0.99 meter or about 38 /2 inches. This is equivalent to a saving in lateral displacement of approximately 16% and was discovered in the arrangement of the transposition bars 46 and 47 which are formed to a length of approximately 28 inches (0.710 meter) which represents approximately a half-wave length (0.715 meter) at television channel XIII, or approximately 210 rnc./s.

From the foregoing, it will be seen that there are 4 four dimensions to be considered in connection with the dipole elements 40 of this antenna, namely: 30 inches, the actual length of the quarter-wave dipole elements 40; 33 inches, their effective length when combined to form a dipole such as 13 or 14; and 38 /2 inches, their effective length when operating as component parts of a complete antenna structure in accordance with the present invention. This is to be compared with 28 inches which is the length of the transposition bars 46 and 47, and which is also a half-Wave length at the highest frequency of the operating range for which this specific example of the invention is dimensioned. Thus the two dipoles 13 and 14 are spaced apart from each other by a distance of 28 inches which is slightly less than the actual length of one of the dipole elements 40. It will be appreciated by those learned in the art that the spacing between the clamps 19 and 20 and the length of bars 46 and 47 is determined by the electrical characteristics desired; however, with the arrangement as described, I have found that currents regaining on theind'ividual dipoles 13 and 14 at all frequencies within the present television range of 54 to 216 'mc./s. will partially or wholly add in phase across the upper and lower terminals, thereby providing a signal greater than that which would appear across the terminals of either dipole or antenna formed thereby alone. This effect is achieved without disturbing the highly desirable uniform bi-directional Figure of 8 pattern of the antenna.

In its preferred embodiment antenna 10 provides a positive figure of gain with respect to a standard dipole cut to a specific frequency range for each channel with the exception of channel II at which frequency range it shows approximately unity gain. In etfect, the fact of unity gain at channel II is found to be due to the total contributions of both of the interconnected pairs of loops since either dipole alone, being appreciably shorter than a half-wave at this frequency, would show substantially less than unity gain if not interconnected onewith the other as disclosed hereby.

The broad band characteristics, essential in television reception for proper response to all frequency components of the television signal, attained is believed to be due to the large effective diameter of the dipole elements 40. The use of looped Wires in forming elements 40 provides an effective cross-section which could be achieved in conventional antennas only by the use of very large diamet'er tubeso'r rods, or by equivalent open ended conesections such as a triangular plate. It is evident that wire looped elements 40 effect an appreciable saving in weight, cost and wind resistance.

The wire construction of elements 40 present a very limited surface to which ice can adhere so that ice loading becomes a negligible factor. This advantage plus the fact that with the aluminum construction described the antenna 10 of this invention weighs less than two pounds makes it highly advantageous for use at locations where support strength is limited.

The form of the invention illustrated and described herein is the preferred embodiment of the present assemblage in the form now commercially manufactured; however, it is to be understood that this embodiment is for illustrative purposes only and it is pointed out that various modifications and alterations may be made within the scope of the appended claims.

I claim:

1. An antenna structure comprising a first dipole consisting of two elements, each element comprising a continuous wire shaped in the form of a smoothly rounded, fiat, symmetrical loop enlarged toward its outer end and constricted at its inner end, the constricted ends of the two elements being positioned adjacent to each other said enlarged outer ends of each loop being rounded pursuant to its natural radius when the constricted inner ends are positioned adjacent to each other, each loop lying in a vertical plane, the dipole having an individual resonant frequency; a second dipole consisting of two elements each of the same shape as the elements of the first dipole and extending with their axes of symmetry substantially parallel to the axes of symmetry thereof and coplanarly and coextensively therewith and having the same individualresonant frequency as the first dlPOICjIWO transposition bar's extending between constricted ends of diagonally opposite elements of the two dipoles; and supporting means maintaining the two dipoles with their axes of symmetry spaced from each other by a distance of approximately one-quarter wave length at the individual resonant frequency of the two dipoles.

2. An antenna structure according to claim 1 in which the length of the transposition bars is less than the length of one of the dipole elements.

References Cited in the file of this patent UNITED STATES PATENTS Wheeler Feb. 20, 1940 Pickles et a1 Aug. 2, 1949 Willoughby June 6, 1950 Ercolino Aug. 8, 1950 Epstein Nov. 21, 1950

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