X-Band Multi-Channel Digital Beamforming Transmit Array Employing both Waveform Agility and Spatial Diversity

"A multi-channel transmit array is to be developed for high-speed digital communications and radar applications. Digital beamforming (DBF) will be combined with direct digital synthesis (DDS) waveform generation to achieve a system capable of using bothwaveform diversity and spatial diversity. Multiple simultaneous transmit beams will be generated that may be configured and scanned digitally. Using DBF, the beamwidths, beam-shapes, scan locations and null locations of the multiple beams are allcontrolled digitally and may be adjusted rapidly for example to follow a moving target, suppress a hostile jammer or to reduce multi-path. The DDS technique will be used to produce various transmit waveforms for high-speed secure communications atrelatively low transmit power levels over a noisy channel. Digital control of the DDS synthesizer allows rapid switching between various communications schemes (CDMA, TDMA, FSK, spread-spectrum, etc.). The synthesizer can also be programmed to producevarious radar waveforms. The DBF and DDS techniques together combine to produce an extremely versatile transmit array that can serve a great many users and applications. We focus here on the development of an X-band communication system; however, thewaveform generation techniques and array architecture developed here may be used in applications ranging in frequency from L-band through EHF. A satellite-based or aircraft-based DBF/DDS communication array woul