Investigations on non-planar wideband electro-magnetic dipole antenna with dielectric superstrate

Abstract

This paper presents the effect of the dielectric superstrates on bandwidth and gain of Electro-Magnetic Dipole (EMD) antenna without and loaded with superstrates. It is found that there is a slight degradation in the performance of the antenna when the superstrate is touching the antenna i.e height of the superstrate above the EMD (H =0 mm). Further, it is also observed that the degraded performance characteristics of the EMD antenna can be improved by placing the dielectric superstrates above the EMD at optimum height (H) = Hopt. The EMD antenna without dielectric superstrate achieves an impedance bandwidth of 3.354 GHz (SWR< 2) at 3.20 GHz, and loaded with dielectric superstrates which shows that the resonate frequency is decreased and achieved impedance bandwidth is 3.351GHz (SWR< 2) at 3.37 GHz. As the dielectric constant of the superstrate increases, it has been observed that the center frequency 3.39 GHz and gain is decreased to 7.40 dB from 7.52 dB. As the height of the superstrate is increased the performance of the antenna improves and at particular optimum height, the gain and bandwidth for all the superstrates will be closer to the free space radiation conditions of the EMD antenna without superstate. However, the return-loss for all dielectric constants of the superstrates is more than −18.60 dB which is well above the acceptable limit. The variation in return-loss is within acceptable limits. This antenna is stable radiation pattern with low cross polarization, low back radiation, nearly identical E- and H-plane patterns. There is a good agreement between simulated and measured results.