Broadband aperture‐coupled conducting sphere antenna

Abstract

An aperture-coupled conducting sphere antenna is proposed, whereby a signal is fed to the antenna from a microstrip feed line via an aperture on the ground plane. Broadband characteristics are achieved by the gradual change of spacing between the ground plane and the conducting sphere. An equivalent network was developed, with its associated circuit element values extracted both analytically and numerically. Based on the results of a parameter study, an X-band antenna was designed for broadband, low loss, and highly efficient operation. It was then fabricated to validate the design. The measured S 11 , showing broadband characteristics, was found to be in reasonable agreement with predictions from the numerical simulation. In addition, far-field radiation patterns were investigated. For applications involving arrays, the coupling characteristics along the E-and H-planes were also examined and compared with other antenna configurations.