System and method for suppressing IFF responses in the sidelobes and backlobes of IFF interrogator antennas

• US 7,705,770 B2
• Filed: 07/18/2005
• Issued: 04/27/2010
• Est. Priority Date: 07/16/2004
• Status: Active Grant

• Current Assignee: Telephonics, Inc. (Griffon Corporation), Telephonics Corporation (TTM Technologies Incorporated)
• Original Assignee: Telephonics, Inc. (Griffon Corporation)
• Inventors: Wahl, Robert
• Primary Examiner(s): Black; Thomas G
• Assistant Examiner(s): Chen; Shelley
• Application Number:
  US11/183,569
• Publication Number:
  US 20060284759A1
• Time in Patent Office: 1,744 Days
• Field of Search: 342 42- 51
• US Class Current: 342/45
• CPC Class Codes: G01S 13/762 with special measures concerning the radiation pattern, e.g. S.L.S. aerials or aerial systems providing at least two radiation patterns, e.g. providing sum and difference patterns, H01Q25/00
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence

Abstract

An IFF interrogation system for use on an aircraft is described. The system transmits a signal from an interrogator to a transponder and from the transponder to the interrogator. The system includes a non-reciprocal IFF antenna that breaks either an uplink signal or a downlink signal at any given angle outside the main beam. The IFF transmitter transmits an Uplink Σ signal and an Uplink Δ signal to the IFF antenna.

Claims

1. An IFF interrogation system for use on an aircraft, said system transmitting a signal from an interrogator to a transponder and a signal from said transponder to said interrogator, said system comprising

an IFF transmitter and receiver, said IFF transmitter and receiver generating a sum signal and a difference signal,

an IFF antenna, said IFF antenna establishing a link with said transponder and transmitting a sum and difference signal to said transponder, said IFF antenna receiving a signal from said transponder, said IFF antenna breaking said link via either an uplink signal or downlink signal when said uplink signal or said downlink signal has said difference signal greater than said sum signal at any given angle outside a main beam,

a plurality of non-reciprocal auxiliary antenna elements, said non-reciprocal auxiliary antenna elements transmitting the difference signal, wherein at any given angle the sum beam gain is not greater than the difference beam gain on both transmit and receive.

2. The system according to claim 1 wherein said IFF transmitter and receiver sends said sum signal to an attenuator, said attenuator sends said sum signal to said IFF antenna.

3. The system according to claim 2 wherein said IFF transmitter and receiver sends said difference signal to a coupler and wherein said coupler sends said difference said IFF antenna and a non-reciprocal feed network.

4. The system according to claim 3 wherein said non-reciprocal feed network has a means for generating a plurality of non-reciprocal signals and sends said plurality of non-reciprocal signals to said plurality of non-reciprocal auxiliary antenna elements for transmission as a difference signal.

5. The system according to claim 1 wherein said IFF antenna has a small vertical aperture.

6. The system according to claim 5 wherein the vertical aperture is less than λ

/2 tall.

7. The system according to claim 1 wherein the uplink or the downlink is broken in the side lobe beam.

8. The system according to claim 7 wherein an isolator is used to make the Uplink antenna side lobe pattern non-reciprocal to the downlink.

9. The system according to claim 1 wherein the IFF antenna is collocated with the radar antenna for an aircraft installation.

10. An IFF interrogation system for use on an aircraft, said system transmitting a signal from an interrogator to a transponder and a signal from said transponder to said interrogator, said system comprising

an IFF transmitter and receiver, said IFF transmitter and receiver generating a sum signal and a difference signal,

an IFF antenna, said IFF antenna establishing a link with said transponder and transmitting a sum and difference signal to said transponder, said IFF antenna receiving a signal from said transponder, said IFF antenna breaking said link via either an uplink signal or downlink signal when said uplink signal or said downlink signal has said difference signal greater than said sum signal at any given angle outside a main beam,

a plurality of non-reciprocal auxiliary antenna elements, said non-reciprocal auxiliary antenna elements transmitting the difference signal, wherein IFF antenna array elements are combined so that the main lobe is reciprocal but the side lobes are not, thereby precluding round trip IFF links.