Low-Cost Hybrid Implementation of an Efficient E-Band Array Based on Stepped and Ridged Slots

In this work, an $8\times 8$ waveguide antenna array composed of stepped and slotted radiators for E-band applications is presented. The proposed array architecture, including the feeding network, can be realized through the integration of a single metallic block adhered with an additional top photo-etched sheet. This approach effectively reduces manufacturing complexity, resulting in a low-cost solution that can be easily fabricated using standard market-ready technologies. Array beam-forming network’s building blocks: transitions, power dividers and $2\times 2$ slotted splitters are presented. Parasitically coupled cavities, inserted in between slotted radiators, help to improve the matching and gain of the array. Stepped profile which has been applied to both active and parasitically coupled apertures, prove to enhance antenna parameters. The overall structure fills a volume of $25\times 24\times 2$ mm 3. A 23.6% fractional bandwidth was achieved in the range of 69 - 86.7 GHz. Radiation characteristics were investigated for both $2\times 2$ splitter radiators and $8\times 8$ antenna arrays where the obtained average gain values were 12 and 25 dBi, respectively. A four-channel prototype was fabricated and measured. The measured radiation patterns agree with the simulated patterns, with a maximum aperture efficiency of 86%.