Reactive combiner for active array radar system
AssigneeRaytheon Company
InventorsLeon Green, Joseph A. Preiss
Life of this patent
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Abstract
An active array radar system is controlled by photonic signals. The array of N antenna elements is divided into M subarrays, each having N/M antenna elements. Tunable lasers provide M optical wavelengths within non-overlapping bands. For reception, the microwave signals are optically modulated onto a single fiber for each subarray. Time delays are introduced for an offset between elements in a subarray and for an offset between subarrays. By using wavelength division multiplexing, a true time delay is attributed to each antenna element on the array. A non-coherent optical combiner having an array of N photodetectors demodulates the receive signals and recovers the coherent sum of the RF signals.
Claims44
In a phased array radar system having a plurality of N antenna elements, a receiver circuit comprising:
- a plurality of M optical carrier signals, each optical carrier signal having a unique wavelength and wherein N is an integer multiple of M;
- a plurality of N optical transmission lines coupled to respective antenna elements, each optical transmission line providing an optical carrier signal modulated by a radio frequency signal received at the coupled antenna element;
- and
- a combiner circuit coupled to the optical transmission lines, the combiner including a plurality of photodetectors to convert the modulating radio frequency signals into a combined radar receive signal.
In a phased array radar system having a plurality of N antenna elements, a method of operating a receiver circuit comprising the steps of:
- generating a plurality of M optical carrier signals, each optical carrier signal having a unique wavelength and wherein N is an integer multiple of M;
- coupling a plurality of N optical transmission lines to respective antenna elements;
- geenrating an optical carrier signal modulated by a radio frequency signal received at the coupled antenna element on each optical transmission line;
- and
- coupling combiner circuit to the optical transmission lines to convert the modulating radio frequency signals into a combined radar receive signal, the combiner having a plurality of photodetectors.
In a phased array radar system having a plurality of N antenna elements, a receiver circuit comprising:
- a plurality of M optical carrier signals, each optical carrier signal having a unique wavelength and wherein N is an integer multiple of M;
- a plurality of N optical transmission lines couple to respective antenna elements, each optical transmission line providing an optical carrier signal modulated by a radio frequency signal received at the coupled antenna element;
- and
- a combiner circuit coupled to the optical transmission lines, the combiner including a phase shifter and a plurality of photodetectors to convert the modulating radio frequency signals into a combined radar receive signal.
In a phased array radar system having a plurality of N antenna elements, a receiver circuit comprising:
- a plurality of M optical carrier signals, each optical carrier signal having a unique wavelength and wherein N is an integer multiple of M;
- a plurality of N optical transmission lines couple to respective antenna elements, each optical transmission line providing an optical carrier signal modulated by a radio frequency signal received at the coupled antenna element;
- and
- a combiner circuit coupled to the optical transmission lines, the combiner including a plurality of Metal-Semiconductor-Metal photodetectors to convert the modulating radio frequency signals into a combined radar receive signal.
In a phased array radar system having a plurality of N antenna elements, a method of operating a receiver circuit comprising the steps of:
- generating a plurality of M optical carrier signals, each optical carrier signal having a unique wavelength and wherein N is an integer multiple of M;
- coupling a plurality of N optical transmission lines to respective antenna elements;
- generating an optical signal modulated by a radio frequency signal received at the coupled antenna element on each optical transmission line;
- and
- coupling a combiner circuit to the optical transmission lines to convert the modulating radio frequency signals into a combined radar receive signal, the combiner circuit having a phase shifter and a plurality of photodetectors.
In a phased array radar system having a plurality of N antenna elements, a method of operating a receiver circuit comprising the steps of:
- generating a plurality of M optical carrier signals, each optical carrier signal having a unique wavelength and wherein N is an integer multiple of M;
- coupling a plurality of N optical transmission lines to respective antenna elements;
- generating an optical signal modulated by a radio frequency signal received at the coupled antenna element on each optical transmission line;
- and
- coupling a combiner circuit to the optical transmission lines to convert the modulating radio frequency signals into a combined radar receive signal, the combiner circuit having a plurality of Metal-Semiconductor-Metal photodetectors.
Dependencies are inferred from the claim text.