Yagi-Configured Electrically Small Antenna with Quad-Polarization Diversity

A polarization-reconfigurable, high-directivity, Yagi-configured, near-field resonant parasitic (NFRP), electrically small antenna (ESA) is presented. The antenna is composed of a director, a reflector, and an electrically-controlled driven element loaded with four p-i-n (PIN) diodes. Two linear polarization ( x-LP and y ·LP) and two circular polarization (LHCP and RHCP) states are achieved simply by controlling the ON/OFF states of the PIN diodes. The measured results demonstrate that in its x(y)-LP state, the peak realized gain, front-to-back ratio, and radiation efficiency values are, respectively, ~3.08 (3.2) dBi, ~11.0 (11.05) dB, and ~77% (73%), and that in its LHCP (RHCP) state they are, respectively, ~3.0 (3.1) dBi, ~ 12.1 (11.18) dB, and ~ 72% (70%).