A 3-D Printed Spherical Antenna With Bandwidth Enhancement Under Operation of Dual Resonance

In this paper, a three-dimensional (3-D) printed spherical antenna with bandwidth enhancement under the operation of TM101 and TM211 modes is presented. The antenna is started from a metallized spherical cavity with a rectangular feed waveguide. Then, some slots are suitably introduced on its sidewall. With the help of these introduced slots, two resonant modes (TM101 and TM211) can be excited simultaneously and merged with each other, resulting in a wideband radiation characteristic with two resonances. An antenna prototype operating at X and Ku bands is designed and implemented as proof of concept. The antenna is additively manufactured by incorporating polymer-based stereolithography and electroless copper plating techniques. Measured results show that the antenna not only owns a wide impedance bandwidth of 40.9% from 9.77 to 14.81 GHz, but also maintains stable radiation patterns over the operating band. Besides, the measured average gain is as high as 10.1 dBi. As the measured results are in good agreement with the simulated ones, a simple and effective design of 3-D printed wideband spherical antenna with high radiation performances is verified.