Circularly Polarized Aperture-Coupled Microstrip-Line Fed Array Antenna for WiMAX/C Bands Applications

In this paper, a new configuration of broad band circularly polarized (CP) array antenna is presented by a modified feeding network The proposed feed network includes two hybrid 90-degree branch line coupler and a 180-degree rat-race coupler. The feed network of array provides sequential rotation condition for consisting of four L-shaped microstrip lines which coupling through four ring-shaped slots. Each element of array is printed on two layer of substrate which connected together with a ring aperture. Employing wideband CP elements and feeding network structure causes the creation of innovation at CP array. The 3dB axial-ratio bandwidth of the array extends to approximately 650 MHz with impedance bandwidths of 24.7% for C-band applications and a relative high gain of about 10.2 dBic. The performance of the antenna has been approved by comparing between measurement and simulation results.