WIDEBAND TRANSMITTER/RECEIVER ARRANGEMENT FOR MULTIFUNCTIONAL RADAR AND COMMUNICATION

• US 20130201050A1
• Filed: 02/17/2010
• Published: 08/08/2013
• Est. Priority Date: 02/17/2010
• Status: Active Grant

• Current Assignee: Saab AB
• Original Assignee: Saab AB
• Inventors: Hellsten, Hans
• Granted Patent: US 9,071,337 B2
• Time in Patent Office: Days
• US Class Current: 342/21
• CPC Class Codes: G01S 13/32 using transmission of continuous waves, whether amplitude-, frequency-, or phase-modulated, or unmodulated
• CPC Class Codes: G01S 13/90 using synthetic aperture techniques , e.g. synthetic aperture radar [SAR] techniques
• CPC Class Codes: G01S 2013/0272 Multifunction radar
• CPC Class Codes: G01S 7/006 using shared front-end circuitry, e.g. antennas G01S13/765, G01S13/825 take precedence
• CPC Class Codes: G01S 7/03 Details of HF subsystems specially adapted therefor, e.g. common to transmitter and receiver
• CPC Class Codes: G01S 7/038 Feedthrough nulling circuits
• CPC Class Codes: G01S 7/4021 of receivers
• CPC Class Codes: H04B 1/44 Transmit/receive switching

Abstract

A transmitter/receiver arrangement comprises a digital arbitrary waveform generator AWG connected to a transmitter. Said waveform generator is configured to generate an arbitrary waveform within a given bandwidth. Said transmitter/receiver arrangement further comprises an antenna arrangement configured to emit a transmitter signal, and to receive an incident signal, a receiver configured to receive a receiver signal, and an analogue isolator connected to said antenna arrangement, said transmitter, and said receiver. Said analogue isolator is adapted to route said transmitter signal from said transmitter to said antenna arrangement, and said incident signal from said antenna arrangement to said receiver, and to isolate said transmitter signal from said receiver signal. Said receiver is adapted to cancel any residual transmitter signal in said receiver signal by means of at least one digital model of at least said isolator, said antenna arrangement, and said transmitter.

Claims

1. A wideband transmitter/receiver arrangement for transmitting and receiving electromagnetic waves comprising:

a digital arbitrary waveform generator AWG connected to a transmitter, wherein said waveform generator is configured to generate an arbitrary waveform within a given bandwidth,

an antenna arrangement configured to emit a transmitter signal, and to receive an incident signal,

a receiver configured to receive a receiver signal,

an analogue isolator connected to said antenna arrangement, said transmitter, and said receiver, wherein said analogue isolator is adapted to route said transmitter signal from said transmitter to said antenna arrangement, and said incident signal from said antenna arrangement to said receiver, and to isolate said transmitter signal from said receiver signal,

wherein said receiver is adapted to cancel any residual transmitter signal in said receiver signal by means of at least one digital model of at least said isolator, said antenna arrangement, and said transmitter.

2. The wideband transmitter/receiver arrangement according to claim 1, further comprising a first subtraction unit, which is configured to subtract a first cancellation signal from said receiver signal received from said isolator, said first cancellation signal received from said at least one digital model is configured to correspond to a predicted effect of said waveform on at least said transmitter, said isolator and said antenna arrangement.

3. The wideband transmitter/receiver arrangement according to claim 2, further comprising a second subtraction unit, which is configured to subtract a second cancellation signal from a signal received from an output of said first subtraction unit, said second cancellation signal received from said at least one digital model is configured to correspond to at least a predicted effect of a transmitter noise generated in said transmitter on at least said isolator and said antenna arrangement.

4. The wideband transmitter/receiver arrangement according to claim 2, said at least one digital model comprising a first digital model of at least said isolator and said antenna arrangement, and a digital model of said transmitter, wherein said first cancellation signal corresponds to an output signal of said AWG applied to said digital model of said transmitter and to said first digital model.

5. The wideband transmitter/receiver arrangement according to claim 3, said at least one digital model comprises a second digital model of at least said isolator and said antenna arrangement, wherein said second cancellation signal corresponds to a digitized representation of said transmitter noise applied to said second digital model.

6. The wideband transmitter/receiver arrangement according to claim 5, wherein said digitized representation of said transmitter noise is arranged to be generated by a third subtraction unit, which is coupled to said transmitter, and to said digital model of said transmitter.

7. The wideband transmitter/receiver arrangement according to claim 6, wherein said first and third subtraction units are analogue subtraction units, in that said first digital model is a digital model of at least said isolator, said antenna arrangement and said first analogue subtraction unit, and in that said second digital model is a digital model of at least said isolator, said antenna arrangement, and said third analogue subtraction unit.

8. The wideband transmitter/receiver arrangement according to claim 1, said transmitter comprises a first digital to analogue converter DAC coupled to a power amplifier, wherein said first DAC is connected to said AWG, and said power amplifier is connected to said isolator.

9. The wideband transmitter/receiver arrangement according to claim 5, wherein,

said first subtraction unit is an analogue subtraction unit connected to an output of said isolator via a first attenuator, and to said first digital model via a second DAC,

said second subtraction unit is a digital subtraction unit connected to an output of said first subtraction unit via a first analogue to digital converter ADC, and to said second digital model, and in that

said second digital model is connected to said second subtraction unit via a second ADC, wherein said second subtraction unit is coupled to said power amplifier via a second attenuator, and to said digital model of said transmitter via a third DAC.

10. The wideband transmitter/receiver arrangement according to claim 1, said isolator (4) comprising a power splitter, a first circulator connected to a right antenna of said antenna arrangement, a second circulator connected to a left antenna of said antenna arrangement, and a power combiner, wherein said power splitter is configured to receive a transmitter signal from said transmitter, and to feed said first and second circulators, which are configured to route any incident signals on said right and left antennas to said power combiner, wherein said power splitter and power combiner are configured to supply at an output of said power combiner a difference signal corresponding to a difference between said right and left antenna incident signals, when said right and left antennas are fed in phase, or a sum signal corresponding to a sum of said right and left antenna incident signals when said right and left antennas are fed in opposite phase.

11. The wideband transmitter/receiver arrangement according to claim 10, said isolator further comprising:

a first switch configured to switch the polarity of a signal received from said power splitter and fed to one of said right and left antennas, such that said right and left antennas can be fed in phase, and in opposite phase, and

a second switch connecting said power combiner with said output of said isolator, and configured to switch simultaneous with said first switch, such that to route said difference signal to said output of said isolator when said right and left antennas are fed in phase, and to route said sum signal to said output of said isolator when said right and left antennas are fed in opposite phase.

12. The wideband transmitter/receiver arrangement according to claim 11, wherein,

said first circulator is formed of a first 90-degree hybrid connected by an input port to said power splitter, in that said second circulator is formed of a second 90-degree hybrid connected by an input port to said power splitter,

wherein one of said first and second 90-degree hybrids is connected to said power splitter via said first switch,

said right antenna comprises a first and a second antenna element (34, 33), which are connected to a coupled and transmitted port of said first 90-degree hybrid respectively,

said left antenna comprises a third and a fourth antenna element, which are connected to a coupled and transmitted port of said second 90-degree hybrid respectively,

said power combiner is formed of a 180-degree hybrid, and wherein a first input port of said 180-degree hybrid is connected to an isolator port of said second 90-degree hybrid, a second input port of said 180-degree hybrid is connected to an isolator port of said first 90-degree hybrid, and delta and sum ports of said 180-degree hybrid are connected to said second switch, and

said second switch connects said delta and sum ports with said resistive load, and said output of said isolator.

13. An airborne vehicle comprising an airframe, which is mirror symmetric with respect to a central plane of said vehicle dividing said vehicle in a right and left part as seen from the rear of said vehicle, said airborne vehicle comprising said wideband transmitter/receiver arrangement according to claim 10, and in that said right antenna is arranged on said right part of said vehicle, and in that said left antenna is arranged on said left part of said vehicle, and in that said right and left antennas are arranged symmetrically with respect to said central plane.

14. An arbitrary waveform continuous wave AWCW radar system, especially suitable for providing high resolution microwave SAR, and low frequency SAR, said radar system comprising said wideband transmitter/receiver arrangement according to claim 3, wherein an output of said second subtraction unit is connected to a signal extraction unit for reconstruction of range reflectivity.

15. A wideband RF communication unit for simultaneously receiving any incident RF communication signals and re-transmitting said signals, said communication unit comprising said wideband transmitter/receiver arrangement according to claim 3, wherein said output of said second subtraction unit, which is configured to correspond to incident communication signals on said antenna arrangement, feeds said digital arbitrary waveform generator for substantially immediate re-transmittance of said incident communication signals.

16. (canceled)

17. A method for transmitting and receiving wideband electromagnetic waves said method comprising the steps:

generating an arbitrary waveform within a given bandwidth by means of a digital arbitrary waveform generator AWG connected to a transmitter,

routing a transmitter signal from said transmitter to an antenna arrangement and an incident signal on said antenna arrangement to a receiver, and isolating said transmitter signal from said receiver signal, by means of an analogue isolator connected to said antenna arrangement, said transmitter, and said receiver, and

canceling any residual transmitter signal in said receiver signal (S3) by means of at least one digital model of at least said isolator, said antenna arrangement and said transmitter.

18. A combined radar, surveillance and communication system comprising an AWCW radar system that comprises:

a wideband transmitter/receiver arrangement for transmitting and receiving electromagnetic waves, said wideband transmitter/receiver arrangement comprising;

a digital arbitrary waveform generator AWG connected to a transmitter, wherein said waveform generator is configured to generate an arbitrary waveform within a given bandwidth,

an antenna arrangement configured to emit a transmitter signal, and to receive an incident signal,

a receiver configured to receive a receiver signal,

an analogue isolator connected to said antenna arrangement, said transmitter, and said receiver, wherein said analogue isolator is adapted to route said transmitter signal from said transmitter to said antenna arrangement, and said incident signal from said antenna arrangement to said receiver, and to isolate said transmitter signal from said receiver signal,

wherein said receiver is adapted to cancel any residual transmitter signal in said receiver signal by means of at least one digital model of at least said isolator, said antenna arrangement, and said transmitter,

and said transmitter/receiver arrangement further comprises a second subtraction unit, which is configured to subtract a second cancellation signal from a signal received from an output of said first subtraction unit, said second cancellation signal received from said at least one digital model is configured to correspond to at least a predicted effect of a transmitter noise generated in said transmitter on at least said isolator and said antenna arrangement,

and a wideband RF communication unit for simultaneously receiving any incident RF communication signals and re-transmitting said signals.

19. The radar, surveillance and communication system of claim 18, said wideband RF communication unit comprising:

said wideband transmitter/receiver arrangement for transmitting and receiving electromagnetic waves,

wherein said output of said second subtraction unit, which is configured to correspond to incident communication signals on said antenna arrangement, feeds said digital arbitrary waveform generator for substantially immediate re-transmittance of said incident communication signals.