Low loss double-layer substrate integrated waveguide-hybrid branch line coupler for mm-wave antenna arrays

This paper presents a novel double-layer hybrid branch line coupler (HBLC) design for millimeter-wave (mm-wave) antenna array applications. It is based upon the substrate integrated waveguide (SIW) technique, which is considered to be a low loss and low cost technology. The full-wave solver, HFSS, is used to simulate and optimize the proposed SIW-HBLC for minimum loss performance. The simulated results of the compact design are compared to these of the original (single layer) design presented in the literature. The SIW-HBLC shows a maximum -0.8 dB loss within an operating frequency band of 600 MHz around the center frequency 34.89 GHz.