A module disposed at each radiating element of a phased array antenna, the module having a limiter, a low-noise amplifier and a phase shifter. One embodiment includes a DPDT switch to permit use of a common phase shifter on transmit and receive. On transmit, the DPDT switch is thrown in a position that connects the phase shifter directly to the radiating element. On receive, the DPDT switch is thrown in a position that connects the radiating element through the limiter and low noise amplifier and then to the phase shifter. Another embodiment uses a four-port circulator in place of the DPDT switch, and uses separate phase shifters for transmit and receive. A semi-active module for a constrained feed array uses both a DPDT switch and a circulator and uses a common transmit/receive phase shifter. A semi-active module for a space-fed array uses two DPDT switches, a single phase-shifter and limiter/low-noise amplifier and two antenna elements; one of receive, and one for retransmit. Another module employs a four-port circulator, separate transmit and receive phase shifters, and separate transmit and receive beamforming networks. In a monopulse radar transmitter, a module using a four-port circulator and a separate receive diode phase shifter, limiter and low-noise amplifier is used with a receive monopulse feed, transmit ferrite phase shifters and a transmit series feed.
A metal flared notch radiator with separate and isolated transmit and receive ports for an active array. A 4-port circulator is integrated into the transition of the radiator so that the integrated device has have a separate transmit port, a separate receive port, and a separate termination port to provide isolation between the transmit and receive.
An antenna system and method comprising an antenna having 2+N antenna elements, where N is zero or an odd integer, an algorithm controlled switching circuit having a separate switch associated with each of the elements and a switch control selectively causing the switching circuit to couple an adjacent pair of the antenna elements to their associated switches while maintaining the remaining switches uncoupled from their associated antenna elements. The algorithm controlled switch control includes circuitry for successively coupling each adjacent antenna element pair of the antenna elements to their associated switches, determining a predetermined parameter for each of the antenna element pair and then causing the antenna system to operate with only one of the antenna pairs responsive to determination of the predetermined parameter. The centers of all of the antenna elements are directed in one or the other of two opposite directions and the center of each of the antenna elements is disposed at a different vertex of an equilateral polygon having N sides.
A device and method for splitting received signal energy among plural receivers in which received signal energy is provided to a first receiver which uses a primary portion of the received signal energy and reflects a reflected portion of the received signal energy, and in which the reflected portion is directed to an additional receiver(s) for use. Low loss directional circulators Or couplers may be used to direct the signal. The loss of signal energy to the first and subsequent receiver(s) is significantly reduced.
A system and method to provide maximum power over large angular sectors using an array of transducers is disclosed. Array segments of transducers and phase shifters form a beam from each of the array segments, wherein the set of beams overlap to form a large sector coverage beam. The phase of each of the signals fed to the radiating elements is shifted, such that the difference between beam point directions of the beams of two adjacent array segments is substantially equal to one half of the sum of the beamwidths of the beams of the two adjacent array segments. The phase of each of the signals fed to the radiating elements may also be shifted in proportion to the square of the distance between one end of the array of transducers and the position of each of the plurality of radiating elements.
A modified Synthetic Aperture Radar (SAR) system with reduced sensitivity to range ambiguities, and which uses secondary receiver channels to detect the range ambiguous signals and subtract them from the signal received by the main channel. Both desired and range ambiguous signals are detected by a main receiver and by one or more identical secondary receivers. All receivers are connected to a common antenna with two or more feed systems offset in elevation (e.g., a reflector antenna with multiple feed horns or a phased array with multiple phase shift networks. The secondary receiver output(s) is (are) then subtracted from the main receiver output in such a way as to cancel the ambiguous signals while only slightly attenuating the desired signal and slightly increasing the noise in the main channel, and thus does not significantly affect the desired signal. This subtraction may be done in real time, or the outputs of the receivers may be recorded separately and combined during signal processing.
