US3277488A - Antenna decoupling by means of a lossy dielectric slab - Google Patents

Antenna decoupling by means of a lossy dielectric slab Download PDF

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Publication number
US3277488A
US3277488A US385525A US38552564A US3277488A US 3277488 A US3277488 A US 3277488A US 385525 A US385525 A US 385525A US 38552564 A US38552564 A US 38552564A US 3277488 A US3277488 A US 3277488A
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antennas
ground plane
lossy dielectric
slot
dielectric
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US385525A
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John G Hoffman
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q17/00—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems
    • H01Q17/001—Devices for absorbing waves radiated from an antenna; Combinations of such devices with active antenna elements or systems for modifying the directional characteristic of an aerial

Definitions

  • the present invention relates to flush mounted antennas and more particularly to a means for reducing the coupling between flush mounted antennas in a common conducting ground plane.
  • flush mounted antennas i.e. slots
  • the coupling between flush mounted antennas has been found to be much different than with simple horn antennas, and also quite critical in terms of dielectric constant, dielectric loss tangent and thickness of the dielectric.
  • the method of decoupling, used with horn antennas, based upon absorbing the incident electric field of the feed transmit horn is unsuccessful when used with flush mounted slot antennas.
  • Old methods of obtaining decoupling in flush mounted slot antennas involved the use of chokes in the vicinity of the antennas, but this had the detrimental effect of producing deterioration in the antennas radiation patterns.
  • the decoupling technique of the instant invention involves using a thin slab of dielectric mounted between flush mounted slot type receive and slot type transmit antennas to increase the surface impedance and to dissipate the energy coupled into the dielectric.
  • Another object of the invention is to provide a decoupling means for flush mounted slot antennas by the use of a lossy dielectric slab.
  • a further object of the invention is to provide a high degree of decoupling between slot antenna arrays without causing deterioration in the antennas radiation patterns.
  • the figure of drawing is a diagrammatic representation of a pair of slot antennas decoupled by means of a lossy dielectric mounted therebetween on the surface of a cylindrical vehicle.
  • a transmit slottype antenna and a receive slot-type antenna 12 are mounted in a conducting cylindrical surface 14 with a thin slab 16 of lossy dielectric mounted between the two antennas.
  • the antennas may be mounted in either curved or flat conducting ground surfaces.
  • the dielectric slab 16 can be mounted flush with the antenna slots, or on either side of the conducting ground surface 14.
  • the coupling mechanism between two slot antennas mounted in a conducting ground plane is by means of a surface mode. It has been found that the degree of coupling of this surface mode to the conducting surface is dependent upon the surface impedance of the ground plane. For a highly conducting ground plane this mode is loosely coupled to the surface, and consequently, any
  • the purpose of this invention is to increase the surface impedance in order to couple the mode into the surface very tightly and then dissipate the energy in the lossy dielectric.
  • a high degree of decoupling between slot antenna arrays is obtainable in the instant case without causing deterioration in the antennas radiation patterns by the lossy dielectric slab 16.
  • An antenna decoupling system for reducing the coupling between flush mounted slot-type antennas without producing deterioration in the antennas radiation patterms comprising:
  • the lossy dielectric slab 16 has a two-fold V purpose: to increase the surface impedance of the ground It is therefore to be understood that within the scope of the appended claims the invention may be

Description

Oct. 4, 1966 J. G. HOFFMAN 3,277,488
ANTENNA DECOUPLING BY MEANS OF A LOSSY DIELECTRIC SLAB Filed July 27, 1964 JOHN G. HOFFMAN INVENTOR.
ATTORNEY United States Patent the Navy Filed July 27, 1964, Ser. No. 385,525 5 Claims. ((11. 343-771) The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention relates to flush mounted antennas and more particularly to a means for reducing the coupling between flush mounted antennas in a common conducting ground plane.
. The coupling between flush mounted antennas (i.e. slots) has been found to be much different than with simple horn antennas, and also quite critical in terms of dielectric constant, dielectric loss tangent and thickness of the dielectric. The method of decoupling, used with horn antennas, based upon absorbing the incident electric field of the feed transmit horn is unsuccessful when used with flush mounted slot antennas. Old methods of obtaining decoupling in flush mounted slot antennas involved the use of chokes in the vicinity of the antennas, but this had the detrimental effect of producing deterioration in the antennas radiation patterns.
The decoupling technique of the instant invention involves using a thin slab of dielectric mounted between flush mounted slot type receive and slot type transmit antennas to increase the surface impedance and to dissipate the energy coupled into the dielectric.
It is an object of the invention to provide a means for reducing the coupling between flush mounted antennas in a common ground plane.
Another object of the invention is to provide a decoupling means for flush mounted slot antennas by the use of a lossy dielectric slab.
A further object of the invention is to provide a high degree of decoupling between slot antenna arrays without causing deterioration in the antennas radiation patterns.
Other objects and many of the attendant advantages of this invention will become readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:
The figure of drawing is a diagrammatic representation of a pair of slot antennas decoupled by means of a lossy dielectric mounted therebetween on the surface of a cylindrical vehicle.
As shown in the figure of drawing, a transmit slottype antenna and a receive slot-type antenna 12 are mounted in a conducting cylindrical surface 14 with a thin slab 16 of lossy dielectric mounted between the two antennas. The antennas may be mounted in either curved or flat conducting ground surfaces. The dielectric slab 16 can be mounted flush with the antenna slots, or on either side of the conducting ground surface 14.
The coupling mechanism between two slot antennas mounted in a conducting ground plane is by means of a surface mode. It has been found that the degree of coupling of this surface mode to the conducting surface is dependent upon the surface impedance of the ground plane. For a highly conducting ground plane this mode is loosely coupled to the surface, and consequently, any
obstructions in the ground plane will not cause appreciable decoupling :between the two antennas. Therefore, the purpose of this invention is to increase the surface impedance in order to couple the mode into the surface very tightly and then dissipate the energy in the lossy dielectric.
plane, and to dissipate the energy coupled into the dielectric.
A high degree of decoupling between slot antenna arrays is obtainable in the instant case without causing deterioration in the antennas radiation patterns by the lossy dielectric slab 16.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings.
practiced otherwise than as specifically described.
What is claimed is:
1. An antenna decoupling system for reducing the coupling between flush mounted slot-type antennas without producing deterioration in the antennas radiation patterms comprising:
(a) a common conducting ground plane, (b) a pair of longitudinal slot-type antennas flush mounted in said common conducting ground plane,
(c) a thin slab of lossy dielectric mounted on said common conducting ground plane between said flush mounted antennas,
(d) said lossy dielectric slab increasing the surface impedance of the ground plane between the anten- 4. A device as in claim 1 wherein an array of flush mounted antennas are used.
5. A device as in claim 1 wherein said pair of longitudinal slot-type antennas are parallel mounted.
References Cited by the Examiner UNITED STATES PATENTS 2,981,949 4/1961 Elliott 343771 2,998,602. 10/1961 Cacheris 343782 HERMAN KARL SAALBACH, Primary Examiner.
ELI LIEBERMAN, R. HUNT, Assistant Examiners.
The lossy dielectric slab 16 has a two-fold V purpose: to increase the surface impedance of the ground It is therefore to be understood that within the scope of the appended claims the invention may be

Claims (1)

1. AN ANTENNA DECOUPLING SYSTEM FOR REDUCING THE COUPLING BETWEEN FLUSH MOUNTED SLOT-TYPE ANTENNAS WITH OUT PRODUCING DETERIORATION IN THE ANTENNAS'' RADIATION PATTERMS COMPRISING: (A) A COMMON CONDUCTING GROUND PLANE, (B) A PAIR OF LONGITUDINAL SLOT-TYPE ANTENNAS FLUSH MOUNTED IN SAID COMMON CONDUCTING GROUND PLANE, (C) A THIN SLAB OF LOSSY DIELECTRIC MOUNTED ON SAID COMMON CONDUCTING GROUND PLANE BETWEEN SAID FLUSH MOUNTED ANTENNAS, (D) SAID LOSSY DIELECTRIC SLAB INCREASING THE SURFACE IMPEDANCE OF THE GROUND PLANE BETWEEN THE ANTENNAS AND DISSIPATING ENERGY COUPLED INTO THE DIELECTRIC.
US385525A 1964-07-27 1964-07-27 Antenna decoupling by means of a lossy dielectric slab Expired - Lifetime US3277488A (en)

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3516936A (en) * 1967-07-27 1970-06-23 Us Navy Lossy material for antenna decoupling
US3577147A (en) * 1969-09-08 1971-05-04 Hazeltine Corp Phased array antenna having a wave speeding ground plane
EP0001883A1 (en) * 1977-10-28 1979-05-16 Ball Corporation Apparatus for improving R.F. isolation between adjacent microstrip antenna arrays
US4748449A (en) * 1984-04-02 1988-05-31 Motorola, Inc. RF absorbing ablating apparatus
US5047787A (en) * 1989-05-01 1991-09-10 Motorola, Inc. Coupling cancellation for antenna arrays
DE4314338A1 (en) * 1993-04-30 1994-11-03 Siemens Ag Radio-frequency system of an MR (nuclear spin, NMR) tomography instrument with screening means for E field limitation
WO2004068633A1 (en) * 2003-02-01 2004-08-12 Qinetiq Limited Phased array antenna and inter-element mutual coupling control method
WO2007112850A1 (en) * 2006-03-28 2007-10-11 Diehl Bgt Defence Gmbh & Co. Kg Array comprising high-power microwave generators for emission of high-field-strength pulses
US9537209B2 (en) 2013-05-16 2017-01-03 Space Systems/Loral, Llc Antenna array with reduced mutual coupling between array elements

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2981949A (en) * 1956-09-04 1961-04-25 Hughes Aircraft Co Flush-mounted plural waveguide slot antenna
US2998602A (en) * 1951-10-03 1961-08-29 John C Cacheris Energy decoupling of closely spaced radar antenna horns

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2998602A (en) * 1951-10-03 1961-08-29 John C Cacheris Energy decoupling of closely spaced radar antenna horns
US2981949A (en) * 1956-09-04 1961-04-25 Hughes Aircraft Co Flush-mounted plural waveguide slot antenna

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3516936A (en) * 1967-07-27 1970-06-23 Us Navy Lossy material for antenna decoupling
US3577147A (en) * 1969-09-08 1971-05-04 Hazeltine Corp Phased array antenna having a wave speeding ground plane
EP0001883A1 (en) * 1977-10-28 1979-05-16 Ball Corporation Apparatus for improving R.F. isolation between adjacent microstrip antenna arrays
US4233607A (en) * 1977-10-28 1980-11-11 Ball Corporation Apparatus and method for improving r.f. isolation between adjacent antennas
US4748449A (en) * 1984-04-02 1988-05-31 Motorola, Inc. RF absorbing ablating apparatus
US5047787A (en) * 1989-05-01 1991-09-10 Motorola, Inc. Coupling cancellation for antenna arrays
DE4314338A1 (en) * 1993-04-30 1994-11-03 Siemens Ag Radio-frequency system of an MR (nuclear spin, NMR) tomography instrument with screening means for E field limitation
US5410251A (en) * 1993-04-30 1995-04-25 Siemens Aktiengesellschaft High-frequency system for nuclear spin tomography with shield for delimitation of an electric field
DE4314338C2 (en) * 1993-04-30 1998-07-23 Siemens Ag High-frequency system of a magnetic resonance imaging system with shielding means for an E-field limitation
WO2004068633A1 (en) * 2003-02-01 2004-08-12 Qinetiq Limited Phased array antenna and inter-element mutual coupling control method
US7427967B2 (en) 2003-02-01 2008-09-23 Qinetiq Limited Phased array antenna and inter-element mutual coupling control method
WO2007112850A1 (en) * 2006-03-28 2007-10-11 Diehl Bgt Defence Gmbh & Co. Kg Array comprising high-power microwave generators for emission of high-field-strength pulses
US9537209B2 (en) 2013-05-16 2017-01-03 Space Systems/Loral, Llc Antenna array with reduced mutual coupling between array elements

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