Active transmit phased array antenna with amplitude taper

• US 5,504,493 A
• Filed: 05/09/1995
• Issued: 04/02/1996
• Est. Priority Date: 01/31/1994
• Status: Expired due to Term

• Current Assignee: Globalstar Incorporated
• Original Assignee: Globalstar Incorporated
• Inventors: Hirshfield, Edward
• Primary Examiner(s): Blum, Theodore M.
• Application Number:
  US08/437,931
• Time in Patent Office: 329 Days
• Field of Search: 342/372, 342/361, 342/362, 342/363, 342/364, 342/365, 342/366, 342/373
• US Class Current: 342/372
• CPC Class Codes: H01Q 21/22 Antenna units of the array energised non-uniformly in amplitude or phase, e.g. tapered array or binomial array
• CPC Class Codes: H01Q 23/00 Antennas with active circuits or circuit elements integrated within them or attached to them
• CPC Class Codes: H01Q 25/00 Antennas or antenna systems providing at least two radiating patterns arrangements for changing or varying the orientation or the shape of the directional pattern H01Q3/00

Abstract

A phase array transmitting antenna system, including a plurality of radiating elements, each radiating element is capable of transmitting radiation. One or more constant phase and amplitude amplifiers are affixed to the radiating element in the array, wherein each radiating element is capable of producing radiation of a substantially uniform phase as the other radiating elements in the array, but distinct amplitudes according to patterns which simplify implementation.

Claims

1. A phased array transmitting antenna system for generating multiple amplitude tapered independent simultaneous microwave signal beams, comprising:

an array of antenna units, a plurality of said antenna units of said array comprising a plurality of substantially identical microwave power amplifiers and coupler means for imparting a predetermined phase shift between microwave signals output from said plurality of microwave power amplifiers for providing orthogonal microwave energy signals having selected phases;

each of said plurality of said antenna units of said array transmitting one of multiple, simultaneous microwave beams; and

each of said plurality of said antenna units further comprising a radiating element responsive to said microwave signals output from individual ones said plurality of microwave power amplifiers for transmitting said microwave signals into space as a beam having a direction and shape, each of said individual ones of said plurality of microwave power amplifiers having an output coupled to a respective one of said radiating elements;

wherein all of said plurality of microwave power amplifiers of said array operate with a same power level, wherein first selected ones of said plurality of antenna units radiate with a power level that is n times a power level of second selected ones of said plurality of antenna units for providing a predetermined amplitude taper across said array, wherein n is an integer that is greater than one, and wherein said first selected ones of said plurality of antenna units comprise one of said radiating elements that is coupled to the outputs of n of said microwave power amplifiers.

2. A phased array transmitting antenna system according to claim 1 wherein outputs of said plurality of microwave power amplifiers are coupled into a cavity, wherein said cavity includes a first pair of microwave probes disposed in said cavity 180 degrees apart, a second pair of probes disposed in said cavity 180 degrees apart, said first and second pairs of probes being disposed 90 degrees apart, a first pair of linear microwave power amplifiers connected to said first pair of probes and a second pair of linear microwave power amplifiers connected to said second pair of probes for exciting orthogonal microwave energy in said cavity.

3. A phased array transmitting antenna system according to claim 2 wherein said array is disposed over a surface of a substrate, wherein said substrate includes phase shift means and attenuator means connected to said first and second pairs of amplifiers and probes in said cavity for providing phase quadrature signals to create circular signal polarization wherein one of said pairs of amplifier and probes is excited to right circular polarization and the other of said pairs of amplifiers and probes is excited to left circular polarization.

4. A phased array transmitting antenna system according to claim 3 wherein said phase shift and attenuator means includes a plurality of separate phase shift and attenuator circuits, and a switch matrix connected to each of said phase shift and attenuator circuits to selectively connect separate polarization signals to said pairs of amplifiers and probes in said cavity, said separate polarization signals cooperating with said plurality of microwave power amplifiers for providing the direction and shape of said microwave beam.

5. A phased array transmitting antenna system according to claim 4 wherein said attenuator means are set to provide that said microwave beams transmitted from said radiating elements of said plurality of antenna units are equal to a multiple of a least amplitude of any microwave beam produced by any antenna unit in said array.

6. A phased array transmitting antenna system according to claim 5 further including a plurality of power signals and wherein said phase shift and attenuator circuits for each antenna unit includes a plurality of series connected phase shift and attenuator circuits, each of said plurality of series connected phase shift and attenuator circuits being connected to a separate power signal wherein each of said series connected phase shift and attenuator circuits is associated with a separate beam to be transmitted by said antenna unit, and wherein each of said series connected phase shift and attenuator circuits cooperates with said plurality of microwave power amplifiers for establishing the direction and shape for each associated beam.

7. A phase array transmitting antenna system according to claim 6 further including control means connected to each of said phase shift circuits and attenuator circuits for setting said phase shift circuit at selected values of phase shift to provide desired beam directions and shapes.

8. A phase array transmitting antenna system according to claim 1 wherein each of said microwave power amplifiers comprises a monolithic microwave integrated circuit amplifier.

9. An amplitude tapered phased array antenna, comprising an antenna array comprised of a plurality of substantially concentric zones, each of said zones comprising a plurality of discrete antenna radiating elements each supporting a substantially circularly polarized wavefront, each of said antenna radiating elements within a first, outer zone radiating microwave energy with a unit power level;

said amplitude tapered phased array antenna further comprising at least one second, inner zone, each of said antenna radiating elements within said second, inner zone radiating microwave energy with a power level that is an integer multiple of said unit power level, wherein each antenna radiating element is coupled to an output of at least one microwave energy amplifier, wherein each microwave energy amplifier outputs microwave energy at said unit power level, and wherein individual ones of said antenna radiating elements of said at least one second, inner zone are coupled to outputs of an integer multiple more of said microwave energy amplifiers than individual ones of said antenna radiating elements of said first, outer zone.

10. An amplitude tapered phased array antenna, comprising an antenna array comprised of a plurality of substantially concentric zones, each of said zones comprising a plurality of discrete antenna radiating elements, each of said antenna radiating elements within a first, outer zone comprising a microwave power amplifier having an output and a phase shifter coupled to said output for providing a first output signal and a second output signal that is shifted in phase from said first output signal, said output signals being coupled to said radiating element, said microwave power amplifier being operated at a selected power level;

said amplitude tapered phased array antenna further comprising at least one second, inner zone, each of said antenna radiating elements within said second, inner zone comprising at least two microwave power amplifiers each having an output providing an output signal to said radiating element that is shifted in phase with respect to said other output signal, each of said at least two microwave power amplifiers also being operated at said selected power level, whereby all microwave power amplifiers of said array are operated at a same power level.

11. An amplitude tapered phased array antenna, comprising an antenna array comprised of a plurality of substantially concentric zones, each of said zones comprising a plurality of discrete antenna radiating elements, each of said antenna radiating elements within a first, outer zone comprising a microwave power amplifier having an output and a phase shifter coupled to said output for providing a first output signal and a second output signal that is shifted in phase from said first output signal, said output signals being coupled to said radiating element, said microwave power amplifier being operated at a selected power level;

said amplitude tapered phased array antenna further comprising a second zone that is surrounded by said first, outer zone, each of said antenna radiating elements within said second zone comprising two microwave power amplifiers each having an output providing an output signal to said radiating element that is shifted in phase with respect to said other output signal, each of said two microwave power amplifiers also being operated at said selected power level;

said amplitude tapered phased array antenna further comprising a third zone that is surrounded by said second zone, each of said antenna radiating elements within said third zone comprising four microwave power amplifiers each having an output providing an output signal to said radiating element that is shifted in phase with respect to others of said output signals, each of said four microwave power amplifiers also being operated at said selected power level, wherein all microwave power amplifiers of said array are operated at a same power level, and wherein each of said antenna radiating elements of said second and third zones radiates microwave energy with a power level that is a multiple of the power level radiated by said antenna radiating elements of said first, outer zone.