Investigations on Wideband U-Slot Microstrip Patch Antenna with Dielectric Superstrate

摘要

This paper presents the effect of the dielectric superstates on bandwidth and gain of U-slot microstrip patch antenna without superstrate and loaded with superstates. It is found that there is a degradation in the performance of the antenna when the superstrate is touching the patch antenna i. e the height of the superstrate above the patch H =0 mm. Further, it is also observed that the degraded performance characteristics of the U-slot microstrip patch antenna can be improved by placing the superstrate at optimum height (H) =H_(opt). The patch antenna without superstrate has a bandwidth of 0.20 GHz (SWR≤ 2) at 2.07GHz, and patch antenna loaded with superstrate for H = 0, shows that the resonate frequency is decreased and achieved impedance bandwidth is 0.19 GHz (SWR≤ 2) at 2.07GHz. As the dielectric constant of the superstrate increases, it has been observed that the center frequency varies from 2.07GHz to 1.58 GHz, bandwidth is decreased to 0.19 GHz from 0.20 GHz. Gain is decreased to 6.51dB from 9.50 dB. As the height of the superstrate is increased, the performance of the patch antenna improves and at particular optimum height (H_(opt) the gain and bandwidth (9.5%) for all the superstrates will be closer to the free space radiation conditions of the patch antenna without superstrate. However, for H = H_(opt) the variation in the return-loss is within ± 2.5 dB of the free space radiation conditions for all dielectric constants of the superstrate and it is within acceptable limits. There is a good agreement between simulated and measured results.