Co-Planar Waveguide Fed Dual Band Circular Polarized Slot Antenna

In this paper, a coplanar waveguide (CPW) fed dual band circular polarized (CP) slot antenna is proposed. A modified asymmetric stub loaded feedline is used along with a square shaped slot in the ground plane to achieve two broad impedance bandwidths (|S11|< −10 dB). The top right corner of the slot is truncated with suitable dimensions to obtain two CP bands within the dual resonances. The simulated results show that a band is resonated with center frequency of 1.6 GHz with 41.8% impedance bandwidth and another band is resonated at 3.3 GHz with 30.7% impedance bandwidth (IBW). Axial Ratio bandwidth (ARBW; Axial Ratio ≤ 3 dB) of 260MHz (13.2%) and 110 MHz (2.9 %) are obtained within the lower and upper resonances respectively. The antenna is packed with a layout area of 0.33λ × 0.33λ, where λ being the wavelength for the lower resonant frequency in free space medium. The antenna simulation is done by assuming FR4 substrate with 1.6mm thickness and tan δ= 0.02. The CP radiation patterns are investigated and found to be stable with satisfactory with dominant left hand circular polarization. The antenna has satisfactory gain suitable for GPS and WiMAX applications.