Single-Feed Superstrate Loaded Circularly Polarized Microstrip Antenna for Wireless Applications

The paper presents three single fed circularly polarized square patch antenna structures for wireless communication applications. The antennas resonate from 1.5 to 1.8 GHz and can cover L-band GPS and GSM 1800 band. The antenna-1 consisting of four slits introduced at the boundary of radiating square patch with a cross slot in the centre. The antenna-2 exhibits four slits, a cross slot in the centre with radiating square patch protected using dielectric superstrate. A wider impedance bandwidth of 100 MHz is achieved with superstrate loading. Also, the antenna gain is improved up to a maximum level of 7 dB within the band of operation. Further, stacking of antenna-1 is done using conventional square patch as the parasitic element. The dual-band resonating antenna-3 is achieved with circular polarization in both of the frequency bands. The 3-dB axial ratio bandwidth is 1.1 % for the upper band and 1.3 % for the lower band. Proposed structures are fabricated on the FR-4 epoxy substrate and fed using SMA connector. The measured results are in good agreement with the simulated results.