Miniaturized Circularly Polarized Reconfigurable Capacitance-Loaded Patch Antenna

A novel miniaturized circularly polarized (CP) capacitance-loaded patch antenna with a simple structure and frequency reconfigurability is proposed in this letter. Unlike the conventional half-wavelength patch antenna, the proposed antenna has a cavity-like structure and, hence, does not require a large ground plane to achieve low back-lobe levels. It utilizes capacitance loading, which significantly reduces the size of the antenna in communication devices and systems. To achieve frequency reconfigurability, a pair of orthogonal radiation gaps (equivalent resonance capacitance) are tuned by introducing two varactors. A tuning range from 880 to 947 MHz is achieved by varying the bias voltages. Good −10 dB impedance and 3 dB axial ratio bandwidths are observed at each operating frequency in the tuning range. The reconfigurable antenna gain is between 4.4 and 4.8 dBic. The remarkable advantages of the proposed antenna make it a potential candidate for Internet of Things (IoT) applications.