Both commercial and military wireless-communication applications require systems that can operate over multi-frequency bands. Although a wideband phased-array antenna transceiver system has been looked at as a potential solution, its bandwidth is limited by several system components. At Texas A&M University, however, Seungpyo Hong, Sang-Gyu Kim, Matthew R. Coutant, Christopher T. Rodenbeck, and Kai Chang developed a compact, phased-array-antenna transceiver system that can operate over a 10-to-35-GHz bandwidth. This system offers beam scanning and full-duplex communication.

Building a phased-array antenna system that operates in multi-frequency bands demands a wideband transmit/receive module, wideband antenna element, wideband phase shifter and control circuit, and phased-array architectures. For satellite communications, such systems also must provide compactness, full-duplex operation, and the ability to transmit and receive signals simultaneously. Through a new configuration, the researchers achieved an impressive increase in antenna bandwidth while adding two more millimeter-wave channels to the multiplexer. The result is a compact, six-channel, wideband multiplexer.

Essentially, the system consists of ultra-wideband Vivaldi antennas, a multi-line PET-based phase shifter, a six-channel microstrip multiplexer, and monolithic-microwave-integrated-circuit (MMIC) amplifiers. The multiplexer routes 10-, 19-, and 32-GHz signals to the transmit path and 12-, 21-, and 35-GHz signals to the receive path. For all six channels, the multiplexer shows insertion loss between 2.2 and 3.4 dB. See "A Multiband, Compact, and Full-Duplex Beam Scanning Antenna Transceiver System Operating from 10 to 35 GHz," IEEE Transactions on Antennas and Propagation, Feb. 2006, p. 359.