Microstrip Feed Trapezoidal Shape Antenna Array with Defected Ground Structure for S Band Applications

Abstract

In this proposal new trapezoidal patch microstrip feed antenna array with ground defected by square shape is designed for detailed antenna parameter study in terms of return loss, VSWR, gain and radiation pattern for S band applications from 2 to 3 GHz. The bandwidth and radiation properties of four radiating element arranged in 2 x 2 array has been improved by defecting half of the ground by etching square shape opposite to the vertical feed point. 30 x 70 x 1.6 mm dimension structure has been fabricated in FR4 substrate for low cost applications and performance analyzed in three different planes. With comparison of four element array with full ground, the proposed array with defected ground has proved the improvement in behavior with return loss of -34.687 dB and ideally fit with VSWR of 1.038. Parametric study with feed length and substrate thickness has also been performed optimized decision of structure dimension. This study reveals that by reducing the substrate thickness and increasing the feed length, we can improve the performance of loss reduction. The front view has been simulated with full ground and defected ground for comparison and the compared results shows that the loss reduction of -22 dB has been achieved with VSWR value of 1.03 from 2.28 for defected ground structure. The designed structure has been simulated with CST software and the comparison of simulated results has conform that the proposed structure can be used for S band application like airport surveillance radars with wide bandwidth of 120 MHz and gain of 3.52 dBi. Comparison has been made between the proposed antenna array and the antennas available in literature with respect to bandwidth gain, reflection coefficient and defection type for better understanding.