Gap Coupled Dual-Band Petal Shape Patch Antenna For Wlan / Wimax Applications

A compact gap coupled dual-band patch antenna is proposed for WLAN and WiMAX applications. Two resonating frequencies at 3.6 GHz and 5.2 GHz with a frequency ratio of 1.40 (theoretical), 1.45 (simulated) and 1.48 (measured) are observed. The frequency ratio depends on the thickness of substrate and gap length between the fed and parasitic patches. The impedance bandwidth at lower resonant frequency is 23.7 % (theoretical), 3.9 % (simulated) and 8.7 % (measured) and at upper resonant frequency it is 23.5 % (theoretical), 4 % (simulated) and 9.2 % (measured). Simulated gain of the patch antenna is 1.6 dBi at lower resonant frequency and 4.2 dBi at upper resonant frequency. Voltage Standing Wave Ratio (VSWR) remains below 1.2. The electric and magnetic field radiation patterns at both the resonating frequencies clearly depict that the co-polarization is higher than the cross polarization. Experimental return loss (vertical bar S-11 vertical bar) VS WR, input impedance and group delay are in close agreement with theoretical and simulated (by High Frequency Structure Simulator (HFSS) Software) results.