Wideband Mobile Antenna Design Using a Resonant Feeding Structure

Abstract

Parallel loop feed structures can be used to implement wideband impedance. However, when a parallel loop feed structure is employed, parasitic resonance occurs in certain feed structures, resulting in the degradation of radiation efficiency. This is caused by the inductance and capacitance of the shunt line that is added to achieve the wideband impedance. We compared two antennas, one with a high impedance level and another with a low impedance level, by adjusting the ratio of the inductance to the capacitance of the parasitic resonance. When the parasitic resonance has a high impedance level, there is an improvement in the impedance bandwidth as well as the radiation efficiency of the antenna.