Modified Feed Corner Truncated Square Microstrip Antenna for Circular Polarized Response

Modified design of truncated corner square microstrip antenna fed using modified coaxial feed is presented for circularly polarized response. The corner truncation in patch yields the excitation of dual orthogonal modes whereas the use of modified coaxial feed yields input impedance matching for smaller probe length. The detailed explanations for the above modifications made in the patch on patch resonant mode frequencies and their impedances are explained. Due to optimum spacing in between the diagonal TM
10
and TM
01
modes of square patch, 55 MHz (5.92%) of axial ratio bandwidth occupying inside 236 MHz (23.84%) of input impedance bandwidth is obtained. Modified feed antenna exhibit broadside pattern across the axial ratio and impedance bandwidth with broadside gain of larger than 7 dBi. Using smaller coaxial feed length of
$0.022\lambda_{\mathrm{g}}$
, antenna yields circular polarized bandwidth of greater than 5%, which is a new contribution in this paper. The proposed antenna with above antenna characteristics can be used in applications of mobile and personal communications systems.