Reconfigurable L-band active array antennas for satellite communications

Active array antennas will play a significant role in future communication systems due to the increased need to generate a number of shaped beams and to reconfigure these beams on command. Recent advances in solid-state technology have enhanced the feasibility of employing active antennas for multiple or shaped beams on board satellites. Design and experimental results for two different L-band active arrays using helical and microstrip radiating elements are presented in this paper. Receive feed arrays consisting of seven active modules have been breadboarded, where each module comprises a circularly polarized radiating element, a band-pass filter, a low-noise amplifier, a variable attenuator and a variable phase shifter. The output ports of the active modules are combined through a 7-to-1 beam-forming network. Measured results of the breadboard active arrays demonstrate that the beam shape can be reconfigured from 16° to 48° half-power beam widths, while the beam location can be reconfigured over a ±16° angular region. Low side-lobe and cross-polar levels have been maintained over the scan region.