A Stacked-Plate-Ball Antenna Design for Optimized Gain and Extended Bandwidth

Abstract

This letter presents a novel stacked-plate-ball (SPB) antenna design that enhances radiation gain and impedance bandwidth by incorporating a metal ball (MB) and metal plate (MP) onto the patch antenna. MB 1, MP, and MB 2 are sequentially incorporated at the center of the patch. As the current flows from the microstrip line to the patch, a portion of the current simultaneously enters MB 1, MP, and MB 2, resulting in a distribution of current on their surfaces. Due to the out-of-phase current distribution between the radiators, the radiation fields among the radiators cancel each other, and the radiation fields both at the E- and H-plane counteract each other, creating radiation nulls at these planes while redistributing part of the energy toward the main lobe, thereby enhancing the gain. Concurrently, the radiators with in-phase current distribution concentrate radiation energy in the direction of the main lobe, strengthening the intensity of the radiation field in the main lobe and further optimizing the gain performance of the antenna. Moreover, an additional resonant point is introduced, which increases the impedance bandwidth of the antenna according to the principle of band superposition. Both simulation and measurement results confirm the operational mechanism of this design, demonstrating an increase in gain by nearly 7.5 dBi and an increase in bandwidth by 13.8% compared to conventional differential-fed patch antenna.