An example radar system includes a transmission array and a reception array, each aligned as a linear array. The radar system also includes a transmitter configured to cause transmission of radar signals having a center frequency by the transmission array. The radar system also includes a receiver configured to receive radar signals having the center frequency that are received by the reception array. The radar system also includes a processor configured to process received radar signals from the receiver, and adjust the center frequency from a first center frequency to a second center frequency. The adjusting of the center frequency from the first center frequency to the second center frequency causes the frequency-dependent transmission radiation pattern of the transmission array to tilt in a first direction and the frequency-dependent reception radiation pattern of the reception array to tilt in an opposite direction from the first direction.

Methods of mitigating interference to a Mobile Satellite Service (MSS) satellite from terrestrial Broadband Wireless Access (BWA) base stations are provided. A method includes receiving, at the terrestrial BWA base station, a pilot signal on a satellite downlink frequency, and adjusting terrestrial BWA communication on a satellite uplink frequency that corresponds to the satellite downlink frequency, responsive to the pilot signal.

Multiple subarray antennas each having multiple element antennas, multiple sum signal generation units respectively connected to the multiple subarray antennas, for each generating a sum signal of signals of the multiple element antennas which each of the subarray antennas has; multiple difference signal generation units respectively connected to the multiple subarray antennas, for each generating a difference signal of the signals of the multiple element antennas which each of the subarray antennas has; and an angle measurement unit for performing a beamformer angle measurement on a target by using the sum signals generated by the multiple sum signal generation units and the difference signals generated by the multiple difference signal generation units are included.

A method and apparatus are provided for nulling a radio frequency (RF) beam for a high-altitude platform (HAP). A transmitter generates an RF signal. A primary antenna system generates an RF beam based on the RF signal. One or more processors determine a result indicating whether to modify the RF beam. When the result indicates to modify the RF beam, a detachable nulling subassembly generates nulling signals based on the RF signal to modify the RF beam generated by the primary antenna system.

Disclosed is an antenna array system including an antenna array of N ≥2 antenna elements that output N antenna signals; an interferer-nulling beam forming network (IN-BFN) coupled to the antenna array, N non-linear filters coupled to the IN-BFN, and a desired signal BFN. The IN-BFN may include N “null BFNs” to generate N null signals, each null BFN applying a respective nulling beam weight set to the N antenna signals to generate a respective one of the N null signals. Each respective nulling beam weight set corresponds to a different respective set of (N−1) independent nulls. Each of the N non-linear filters may filter a respective one of the N null signals to provide a respective one of N filtered signals. The desired signal BFN may apply a desired signal beam weight set to the N filtered signals to generate an output signal.

An antenna control device includes a weight unit in which weight values to be superimposed on transmission/reception signals are set for forming radiation patterns using a plurality of antennas and a weight synthesis unit that superposes the weight values on the transmission/reception signals. The antenna control device further includes an arrival direction detector that detects arrival directions of the reception signals, a distribution information calculator that calculates distribution information of the detected arrival directions, a signal quality calculator that calculates signal quality information of each of the radiation patterns, and a radiation pattern selector that selects a radiation pattern on the basis of the distribution information and signal quality information for the radiation patterns, and sets the weight values corresponding to the selected radiation pattern in the weight unit.

A technique is described where the switch and/or tunable control circuit for use with an active multi-mode antenna is positioned remote from the antenna structure itself for integration into host communication systems. Electrical delay and impedance characteristics are compensated for in the design and configuration of transmission lines or parasitic elements as the active multi-mode antenna structure is positioned in optimal locations such that significant electrical delay is introduced between the RF front-end circuit and multi-mode antenna. This technique can be implemented in designs where it is convenient to locate switches in a front-end module (FEM) and the FEM is located in vicinity to the transceiver.

A system is described where antenna beam steering techniques are implemented to optimize time and frequency channel resources in wireless communication systems where repeaters are used. Beam steering modes of the antenna systems in the repeaters as well as the nodes are optimized to improve system capacity and load balancing. Client devices in a wireless LAN system can be configured to work as repeaters, with the repeaters containing a beam steering capability. The beam steering capability can be implemented in one or multiple nodes and repeaters in the communication system.

Disclosed is a system and method for a complex domain radio frequency (RF) frontend, adaptive beamforming can separate the relatively slowly changed waveform delay information required from wideband RF signals, upon which a self-contained beamforming system is implemented with a low-speed baseband. By introducing vector RF multipliers in the frontend of the present invention, the amplitude and phase of RF signals are simultaneously controlled by the real and imaginary parts of complex numbers, such that beamforming algorithms derived in complex domain can be directly applied without any form of transformation. By doing so, the massive use of conventional T/R modules and high-speed baseband devices can be avoided, thus simplifying the realization and decreasing the cost of wideband digital beamforming systems for use in low cost, power efficient beamforming applications.

Methods of mitigating interference to a Mobile Satellite Service (MSS) satellite from terrestrial Broadband Wireless Access (BWA) base stations are provided. A method includes nulling first transmissions in a first base station subsector associated with a first terrestrial BWA base station that is in a first geographical area, and nulling second transmissions in a second base station subsector associated with a second terrestrial BWA base station that is in a second geographical area different from the first geographical area.