A Compact Dual-Mode Circularly Polarized Antenna With Frequency Reconfiguration

A simple compact circularly polarized (CP) cross slot antenna with a wide frequency tuning range has been presented in this letter. Four identical varactors are loaded at the ends of the cross slot for varying the operating frequency, and only one voltage is adopted to control the varactors. Distributed inductors and capacitors are employed to realize CP radiation. By varying the value of varactors, a wide tuning frequency range of 41% (1.65–2.5 GHz) is achieved. Stable CP radiation patterns are obtained for all frequencies across the entire operating bandwidth. The proposed antenna is a good radiator that can be used for Internet of Things (IoT) wireless sensing network, WiFi applications, and reconfigurable array developments.