BROADBAND CIRCULARLY POLARIZED SLOTTED PATCH ANTENNA LOADED WITH SHORT PINS

In this letter, a design for broadband circularly slotted patch antenna fabricated on a single- layered printed circuit board (PCB) with unidirectional radiation is described. It is fed by a simple center-fed feeding scheme. Unlike conventional slotted patch antennas, the proposed antenna is loaded with four short pins such that both matching and axial-ratio (AR) bandwidths are improved. In addition to realize the CP radiation at higher frequencies, a cross-slot with different arm lengths, which is cut from the center-fed patch is used. Then, the proposed antenna operates as magnetic dipoles to generate circular polarization at low frequencies after four short pins are added to connect the patch to the ground. Thus, by combining the two modes, bandwidths of 30.2% (1.83-2.48 GHz) for |S11| < 10 dB and 21.2% (1.98-2.45 GHz) for axial ratio (AR) < 3 dB around the center frequency of 2.15 GHz are measured. Moreover, stable gain of over 8 dBic and good radiation patterns are also observed across the operating band.