Broadband and high gain waveguide-fed slot antenna array in the Ku-band

A broadband and high-gain slot antenna array operating in the Ku-band is reported in this study. The antenna is with waveguide-fed cavity backed configuration and made entirely via simple milling process. The overall antenna structure consists of four layers. The bottom layer is a waveguide feed network to provide corporate power division. In turn, the waveguide feed network is excited by a conventional coaxial probe from the back. The waveguide network couples energy to an array of cavity via an aperture plate. These constitute the middle two layers. Each cavity then excites a subarray of 2 × 2 radiating slots in the top layer. The radiating slot elements and the feed network are designed to achieve wide bandwidth and high-gain performance. Finally, an 8 × 8 array antenna has been designed and fabricated with about 25 dBi gain over 14.8% bandwidth, and the cross-polarisation was around -30 dB in the boresight.