A six‐port network based on substrate integrated waveguide coupler with metal strips

Abstract

In this study, a novel coupling structure based on half-mode substrate-integrated waveguide (HMSIW) is proposed with a small size and broad bandwidth. The HMSIW coupler is realised by connecting their equivalent magnetic walls with metal strips, which avoids exposing the semi-enclosed magnetic walls outside. Hence, it has greater anti-interference capability than the existing HMSIW couplers. The directional coupling principle is introduced by analysing the proposed single connecting strip coupler. In order to lower return loss and higher isolation, a 3 dB directional coupler working from 10.8 to 16.8 GHz is designed with two connecting strips. Finally, a six-port circuit is achieved by utilising this compact 3 dB directional coupler. Furthermore, a broadband HMSIW power divider is optimised to satisfy the performance of this six-port circuit. The proposed coupler with metal strips helps to increase bandwidth and reduce size, which makes it more applicable to demanding systems with complex requirements such as detecting and transceiver systems. The 3 dB coupler and six-port circuit are fabricated and measured. The measured results are in accordance with the simulated data.

A Multi-Aperture Technique for Longitudinal Miniaturization of UWB 3 dB Dual-Layer SIW Coupler

“…Mathematically, it can be wri en as 𝑆 = 𝑆 𝐾 + (𝑆 − 𝑆 𝐾). Using Equation (18), this can be generalized for 𝑛 apertures as follows:…”

“…Progress in substrate integrated waveguide (SIW) technology has paved the way towards further width reduction with the advent of half-mode SIW (HMSIW), which has been immensely utilized with different variations [ 12 , 13 , 14 , 15 , 16 , 17 , 18 ]. By bisecting the conventional SIW through the fictitious magnetic wall, Bing Liu et al [ 12 ] have shown that coupler width can be reduced to half.…”

“…They have designed a coupler based on this structure that yields 28.32% FBW with a length of just 0.517 . In addition to these methods, other techniques have also been developed, such as connecting the magnetic walls with metal strips [ 18 ], using air-filled vias to manipulate the effective permittivity [ 19 ] and using optimization algorithms to design the coupling structure [ 20 ]. Among these methods, only slow wave-based approaches look promising in reducing the length of a coupler.…”