Abstract-A functional microstrip circuit module for annular slot antenna is proposed. This module consists of an annular microstrip line component, two PIN diodes and a DC bias circuit. Reconfigurable circular polarizations can be simply controlled by this functional module. Axial ratio is adjustable by changing the clip angle of the notch made by the annular microstrip line component. Simulated and experimental results have shown good impedance bandwidth for return loss and antenna gains in circularly polarized states.

This report presents a novel arc-microstrip module design being used to modify the surface current on the radiating patch of the slot antenna and to reconfigure its characterizing polarizations activated by pin-diode controlled bias.