Frequency-Tunable Compact Antenna Using Quarter-Mode Substrate Integrated Waveguide

A frequency-tunable compact antenna based on quarter-mode substrate integrated waveguide (QMSIW) technology to reduce the size of the antenna is proposed. The resonant frequency of the antenna is electronically controlled by a dc bias voltage of a varactor loaded between the QMSIW and an additional parasitic patch on the top plane of the structure, with the bias network designed on the bottom plane. The performance of this antenna is demonstrated experimentally, with its resonant frequency varying from 2.28 to 2.50 GHz by increasing the dc bias voltage from 0 to 30 V.