A Novel Substrate Integrated Gap Waveguide Ultra Wide-Band Circular Directional Coupler for Ku Band Applications

Abstract

This study presents a new circular compact Ultra Wide-Band (UWB) substrate integrated gap waveguide (SIGW) based 3 dB hybrid coupler for Ku band applications. The coupling section is a circular structure with an elliptic slot and additional via to achieve equal-power division in two ports and isolation in the 4(th) port. To optimize the design parameters of the hybrid coupler, the Finite Integration Time-Domain (FITD) approach is employed. The operating frequency of the coupler is between 12.14 to 15.4 GHz with a central frequency of 13.5 GHz, a bandwidth of 3.26 GHz, and a Fractional Band Width (FBW) being 23.67%. A phase difference throughout the operational spectrum around 90 has been attained. The coupler is fabricated with an overall dimension of 33.8 x 33.8 mm(2). The measured and simulated scattering parameters demonstrate satisfactory agreement.