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

• US 20060284759A1
• Filed: 07/18/2005
• Published: 12/21/2006
• Est. Priority Date: 07/16/2004
• Status: Active Grant

• Current Assignee: Telephonics, Inc. (Griffon Corporation), Telephonics Corporation (TTM Technologies Incorporated)
• Original Assignee: Telephonics Corporation (TTM Technologies Incorporated)
• Inventors: Wahl, Robert
• Granted Patent: US 7,705,770 B2
• Time in Patent Office: Days
• 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 comprising an IFF transmitter and receiver and a non-reciprocal IFF antenna, said transmitter transmitting an Uplink Σ

signal to said IFF antenna and an Uplink Δ

signal to said antenna.

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

3. The system according to claim 2 wherein the vertical aperture is less than λ

/2 tall.

4. The system according to claim 2 wherein said Σ

signal is transmitted to an attenuator and from the attenuator to said non-reciprocal IFF antenna.

5. The system according to claim 4 wherein said Δ

signal is transmitted by said IFF receiver to a coupler where said signal is split and one Δ

is transmitted to said IFF antenna and the other Δ

signal is transmitted to a non-reciprocal feed network.

6. The system according to claim 5 wherein said Δ

signal is transmitted from said non-reciprocal feed network to one or more auxiliary antenna elements.

7. An IFF interrogation system for use on an aircraft said system transmitting a signal from an interrogator to a transponder and from said transponder to said interrogator, said system comprising a non-reciprocal IFF antenna that breaks either an uplink signal or a downlink signal at any given angle outside the main beam.

8. The system according to claim 7 wherein said IFF antenna has a small vertical aperture

9. The system according to claim 8 wherein the vertical aperture is less than λ

/2 tall.

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

12. The system according to claim 7 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.

13. The system according to claim 10 wherein an isolator is used to make the Uplink antenna side lobe pattern non-reciprocal to the downlink.

14. The system according to claim 10 wherein a switch is used to make the Uplink antenna side lobe pattern non-reciprocal to the downlink.

15. The system according to claim 10 wherein a filter is used to make the Uplink antenna side lobe pattern non-reciprocal to the downlink.

16. The system according to claim 10 wherein non-reciprocal phase lengths are used to make the Uplink antenna side lobe pattern non-reciprocal to the downlink.

17. The system according to claim 7 wherein the IFF antenna is collocated with the radar antenna for a aircraft installation.

19. The method according to claim 14 further comprising modifying the side lobe structure from transmit to receive so that at any given angle the sum beam gain is not greater than the difference beam gain on both transmit and receive.

11. The system according to claim 11 wherein at any given angle the sum beam gain is not greater than the difference beam gain on both transmit and receive.

18. A method of reducing back lobe in an IFF interrogation system for use in an aircraft comprising establishing a round trip IFF link from interrogator to transponder and transponder to interrogator with a non-reciprocal IFF antenna so that for any given angle outside a main beam, either the uplink or the downlink is broken.