A reconfigurable patch antenna with independent frequency and polarization agility

Abstract

ABSTRACTA frequency and polarization reconfigurable patch antenna is proposed in this letter. The antenna consists of a circular patch surrounded by four sector-shaped patches. Four pairs of varactor diodes are introduced to bridge the gaps between the circular patch and the sector-shaped patches; the capacitance of the varactors is controlled by two DC signals. By adjusting the reverse bias voltage of the varactors, the proposed antenna can switch between linear polarization (LP), right-hand circular polarization (RHCP) and left-hand circular polarization (LHCP). Furthermore, the operating frequency of each polarization state can be independently tuned. A prototype has been designed and fabricated. The results indicate the proposed antenna with a continuously tunable frequency range from 1.82 to 2.28 GHz in LP states, and from 1.88 to 2.25 GHz in either RHCP or LHCP states. Meanwhile, stable radiation patterns with low cross-polarization and back radiation levels (<−15 dB) are achieved for all states.