An L-band tunable microstrip antenna using multiple varactors

A tunable rectangular microstrip antenna at L-band is designed, fabricated and measured. 8 varactors are placed at the two radiating edges of the antenna. The resonant frequency is tuned from 1.45 to 1.8 GHz (tunability of 24%). The return loss is less than -12 dB over the entire tuning range and the maximum gain is 7.58 dB. Multiple varactor loaded antennas achieve higher gain than single varactor loaded ones reported previously.