This study investigated the effects of the shorting-pin position on the impedance bandwidth, radiation efficiency, and cable sensitivity of an antenna mounted on a small ground plane. When the shorting pin was placed in a region of strong charge distribution on the ground plane, the coupling between the antenna and the ground was enhanced, resulting in an improved impedance bandwidth and radiation efficiency. Furthermore, the influence of a nearby cable was experimentally verified to consider realistic operating conditions. Although the presence of the cable slightly degraded impedance matching, it acted as a parasitic radiator, leading to an increase in the radiation efficiency.
Wi et al. (Sun,) studied this question.