Circular Polarized Antenna with Improved Axial Ratio Bandwidth for GSM Application

As the circular polarization and compact size are more important parameters in designing of current microstrip patch antennas. In this paper, triangle shaped spiral microstrip patch antenna is reported for GSM application. For the perfect matching between probe and microstrip rectangular line, single stub matching concept is used. For improving the bandwidth of the antenna, defected ground structure is introducing. The reported antenna is resonating at 890 MHz and covers (840–930) MHz frequency Band. The covering axial ratio frequency band is (680–1005) MHz at 3 dB, hence designed antenna is circular polarized over the band. The other improved parameters are also observed i.e gain varies 8.4∼8. 7 dB; return loss −23 dB and radiation efficiency lies between 84-86%. Also getting acceptable SAR value 1.0 W/kg near human tissues at resonant band. Recommended dimensions of the antenna is
$36\times 30\times 1.676\ \text{mm}^{3}$
, which shows that structure is very compact in size.