Frequency-Reconfigurable Antenna Element for X-/Ku-Band Satellite User Terminals

This letter presents a compact X-/Ku-band frequency- and polarization-reconfigurable antenna element in the array antenna layer for user terminals in satellite communication, implemented using p-i-n diodes. The antenna element integrates two p-i-n diodes to enable frequency reconfiguration for half-duplex operation: RX mode covers 10.7 GHz to 12.7 GHz with horizontal polarization, and TX mode operates at 13.85 GHz to 14 GHz with vertical polarization. Parasitic patches are incorporated in the RX mode to achieve wideband coverage with a flat gain response. In both modes, the antenna maintains a stable realized gain of approximately 5 dBi to 6 dBi. Circular polarization is achieved by arranging four linearly polarized elements in a rotational sequence. A 4 × 4 element array prototype was fabricated and tested in an anechoic chamber, demonstrating peak realized gains of 15.8 dBic (RX) and 13.2 dBic (TX), with cross-polarization isolation exceeding 20 dB. These results indicate that the proposed antenna is a promising candidate for compact, reconfigurable user terminals in half-duplex satellite communication systems.