A Study of Conductor Effects in Ground Antennas

Abstract

A ground plane plays an important role in mobile antenna designs. The performance of mobile antennas may significantly be affected as the ground condition is changed. This work analyzes an effect of a conductor connected near a ground antenna. In order to demonstrate the change on the resonant frequency and the radiation efficiency, the surface current distribution of the antenna was investigated as the conductor length and position are changed. In this thesis, the antenna is designed to operate at Wi-Fi application (2.4 GHz - 2.5 GHz) with required fractional impedance bandwidth of 6.5% for S11<-10 dB. It is verified via simulated and measured that the antenna efficiency is decreased as much as 10% in comparison with original ground antenna, when the conductor is λ/4 in length. To solve this problem, a lumped inductor is utilized to decouple between the antenna and the conductor, and the improvement in the performance of the antenna could be confirmed.