Ka-Band Integrated Multilayer Pyramidal Horn Antenna Excited by Substrate-Integrated Gap Waveguide

This work proposed a solution of structures built from stacking several dielectric substrates with the conducting cladding, aiming for electrical contact between them [perfect electric conductor (PEC)-PEC]. At mm-wave frequencies, surface roughness or imperfect flat surfaces present possible gaps that cause severe unexpected leakage. Many engineers overlooked this problem. To prevent this leakage, we propose transforming one of the PEC-PEC surfaces into artificial magnetic conductors (AMCs), creating a PEC-AMC layer that suppresses any leakage even with no contact between the surfaces where the gap is less than a quarter wavelength. A wideband multilayer pyramidal horn antenna using substrate-integrated gap waveguide (SIGW) technology is proposed as an example that highlights the proposed solution. In each layer of the horn, the opening is surrounded by periodic cells to suppress leakage and surface waves. In addition, the upper surface surrounding the horn's opening is surrounded by EBG mushroom cells to act as a soft surface that suppresses the surface waves and reduces the edge diffraction, and, in turn, improves the radiation characteristics of the horn. The horn achieved a gain of 11.5 dBi and 20.5% bandwidth (28.5-35 GHz). The simulated and measured results show excellent agreement with each other.