Single channel transceiver with polarization diversity

• US 5,982,329 A
• Filed: 09/08/1998
• Issued: 11/09/1999
• Est. Priority Date: 09/08/1998
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: The United States Of America As Represented By The Secretary Of The Army
• Inventors: Pittman, William C., Halladay, Ralph H.
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): CHEN, SHIH CHAO
• Application Number:
  US09/149,251
• Time in Patent Office: 427 Days
• Field of Search: 343/700 MS, 343/769, 343/846, 343/829, 343/754, 342/175
• US Class Current: 343/700.0MS
• CPC Class Codes: H01Q 1/38 formed by a conductive layer on an insulating support patch antennas H01Q9/0407; microstrip dipole antennas H01Q9/065; microstrip slot antennas H01Q13/106; transmission line microstrip antennas H01Q13/206; manufacturing reflecting surfaces using insulating material for supporting the reflecting surface H01Q15/142
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H01Q 9/0435 using two feed points

Abstract

The single channel transceiver with polarization diversity is a target detion and tracking system that results from combining the well-established technology of single channel transceiver with that of microstrip polarization-diverse antenna. The single channel transceiver with polarization diversity transmits a pair of pulses of a pre-selected polarization sense toward a target object and receives two scattered pulses of orthogonal polarizations in rapid sequence. Thereupon, a second pair of pulses, this time of opposite polarization, is transmitted and, again, two scattered pulses of orthogonal polarizations from this second pair of transmitted pulses are received in rapid sequence. Thus, the single channel transceiver with polarization diversity has the capability to obtain the complete scattering matrix of a target by use of four transmitted pulses. The received scattered pulses are further processed by the transceiver to derive the polarization signature that is indicative of the nature of the object from which they scattered in reflection and thereafter used to identify the target among clutter or background.

Claims

1. In a single channel transceiver having a pulse modulator for producing pulse trains, a signal processor for processing received scattered pulses and producing switching signals therefrom and a duplexer for maintaining separation between the transmitting and receiving functions of said transceiver;

an improvement for imparting polarization diversity to said transceiver such that radiant energy of differing polarization senses may be transmitted from or received by said transceiver, said improvement comprising a microstrip antenna, said antenna having a conductive strip, a conducting ground plane and a dielectric substrate sandwiched between the strip and the plane, a power connector coupling the strip with the duplexer, said antenna further having a first diode and a second diode, the first diode being located in a pre-determined position with respect to the second diode and each diode providing a conductive path between the strip and the ground plane so as to result in transmission and reception of radiant energy of pre-determined polarization senses upon selective application of voltages to the diodes; and

a means for selecting and controlling the application of voltages to the diodes, said selecting means being coupled simultaneously between the modulator, the signal processor and said microstrip antenna.

2. An improvement for imparting polarization diversity to a single channel transceiver as set forth in claim 1, wherein said selecting and controlling means comprises a polarization controller coupled between the pulse modulator, the signal processor and said microstrip antenna.

3. An improvement for imparting polarization diversity to a single channel transceiver as set forth in claim 2, wherein said polarization controller comprises a pulse shaper coupled to receive the pulse train from the pulse modulator and produce an output of trigger pulses, said pulse shaper being further coupled to the signal processor to receive the switching signals therefrom.

4. An improvement as set forth in claim 3, wherein said polarization controller further comprises a first bistable circuit and a second bistable circuit, both circuits being coupled to receive said trigger pulses from said pulse shaper and emit voltages simultaneously in response to said trigger pulses.

5. An improvement as set forth in claim 4, wherein said first bistable circuit is coupled to the first diode of said microstrip antenna and said second bistable circuit is coupled to the second diode of said microstrip antenna, said second bistable circuit further having therein an inverter circuit to cause said second bistable circuit to emit a voltage of opposing polarity from the polarity of voltage emitted by said first bistable circuit and said pulse shaper responds to said switching signals and causes said bistable circuits to alternate between applying a positive voltage and applying a negative voltage to their respectively-connected diodes such that said antenna achieves a given pattern of transmitting and receiving radiant energy of pre-determined polarizations.

6. In a single channel transceiver having a pulse modulator for producing pulse trains, a signal processor for processing received scattered pulses and producing switching signals therefrom and a duplexer for maintaining separation between the transmitting and receiving functions of said transceiver;

an improvement for imparting polarization diversity to said transceiver such that radiant energy of differing polarization senses may be transmitted from or received by said transceiver, said improvement comprising a plurality of identical microstrip antennas, each of said antennas having a conductive strip, a conducting ground plane and a dielectric substrate sandwiched between the strip and the plane, a power connector suitable for coupling power to the strip, each of said antennas further having a first set of multiple diodes and a second set of multiple diodes, the first set and the second set of diodes being arranged in pre-determined locations with respect to each other and each diode of each set providing a conductive path between the strip and ground plane so as to result in the transmission from and reception by said antenna of radiant energy of pre-determined polarization senses upon selective application of voltages to the diodes;

a means for selecting and controlling the application of voltages to the diodes, said selecting means being coupled simultaneously between the pulse modulator, the signal processor and said plurality of antennas and a power divider, said divider being coupled between the duplexer and the power connectors.

7. An improvement for imparting polarization diversity to a single channel transceiver as set forth in claim 6, wherein said selecting and controlling means comprises a polarization controller coupled between the pulse modulator, signal processor and to each of said microstrip antennas.

8. An improvement for imparting polarization diversity to a single channel transceiver as set forth in claim 7, wherein said polarization controller comprises a pulse shaper coupled to receive the pulse train from the pulse modulator and produce an output of trigger pulses, said pulse shaper being further coupled to the signal processor to receive the switching signals therefrom.

9. An improvement as set forth in claim 8, wherein said polarization controller further comprises a first bistable circuit and a second bistable circuit, both circuits being coupled to receive said trigger pulses from said pulse shaper and emit voltages simultaneously in response to said trigger pulses.

10. An improvement as set forth in claim 9, wherein said first bistable circuit is coupled in parallel to all of the first sets of diodes of said plurality of microstrip antennas and said second bistable circuit is coupled in parallel to all of the second sets of diodes of said plurality of microstrip antennas, said second bistable circuit further having therein an inverter circuit to cause said second bistable circuit to emit a voltage of opposing polarity from the polarity of voltage emitted by said first bistable circuit and wherein said pulse shaper responds to said switching signals and causes said bistable circuits to alternate between applying a positive voltage and applying a negative voltage to their respectively-connected sets of diodes such that said antennas achieve a given pattern of transmitting and receiving radiant energy of pre-determined polarizations.