Design Of Corner Truncated Square Microstrip Antenna For Circular Polarized Response in Global Positioning System L5 Band Application

Design of a circularly polarized corner truncated square microstrip antenna for GPS L5 band application is proposed. The corner truncation in the square patch, degenerate patch fundamental mode into dual diagonally directed orthogonal modes with optimum inter spacing between them yields circular-polarized characteristics. Initially the designs were presented on thinner FR4 and Arlon substrates. In these designs, antenna yields impedance bandwidth of 4--5% with an axial ratio bandwidth of 0. 7 --1%. Based on these optimum configurations, formulation of resonant length and design methodology is presented, using which a similar design is presented to cover global positioning system L5 frequency band. In this band, proposed design on substrate of thickness 0.023$\lambda_{\mathrm{A}\mathrm{R}}$, results in impedance, and axial ratio bandwidth of 79 MHz (6.67%) and 12 MHz (1.02%), respectively, offering broadside radiation pattern and peak gain of 6.1 dBi. Lastly the comparison is presented for the similar design with slotted ground plane, exactly below the patch corners. Configuration with modified ground plane offers 17 MHz (1.44%) of axial ratio and 74 MHz (6.26%) of impedance bandwidth, with a reduced broadside peak gain of 5.7 dBi. With these antenna characteristics, both the proposed low profile designs satisfy the requirement of global positioning system L5 band application. To authenticate the simulated results, measurements have been carried out, which show, similar values.