An Electronically Reconfigurable Microstrip Antenna With Switchable Slots for Polarization Diversity

An electronically reconfigurable microstrip antenna with circular and linear polarization switching is presented. The prototype fabricated on a substrate of dielectric constant (ε
_r
) 4.4 and height (h) 1.6 mm is fed by a proximity feed fabricated using the same substrate. By controlling the bias voltage of two PIN diodes, the polarization of the antenna can be switched between three states; two states for linear polarization (horizontal and vertical) and one state for circular polarization (RHCP). Simulation and experimental results show that the proposed antenna has a cross polar level better than 10 dB in the linear polarization state and 18 MHz axial ratio bandwidth in the circular polarization state. The frequency and polarization diversities of this design could potentially improve the reliability of wireless communication systems.