Novel structure and design of enhanced‐bandwidth hybrid quadrature patch coupler

Abstract

A novel structure and design optimization procedure of an enhanced-bandwidth hybrid quadrature patch coupler is proposed. Improved performance of the circuit has been obtained by parameterizing the coupler sections using splines, which introduces additional degrees of freedom. Due to computational complexity of the parameter adjustment problem, a sequential design procedure is applied. In each iteration, a selected number of spline control points is used and their radial coordinates are optimized. The design found this way is then used as a starting point for the next iteration with an increased number of spline control points. The final design parameterized by 20 control points exhibits over 50% bandwidth at the operational frequency of 10 GHz, and acceptable footprint of 13.8 mm × 15.7 mm. K E Y W O R D Scomputer-aided design, design optimization, EM-driven design, patch couplers, topology evolution

Bandwidth‐size design trade‐offs for compact spline‐parameterised patch couplers by means of electromagnetic‐driven multi‐objective optimisation

“…Consider a microstrip hybrid quadrature PC shown in Fig. 1 [24]. The circuit consists of a spline-parameterised patch and four 50 Ω feed lines.…”

“…Note that the design framework presented in this section is generic. For the sake of illustration, it is demonstrated using a particular structure of a spline-parameterised coupler of [24], as detailed in Section 4 below.…”

“…In this paper, investigations of design trade-offs for splineparameterised hybrid PCs are carried out, here, exemplified for a particular structure operating at 5.6 GHz [24]. Using a sequential domain patching (SDP) algorithm [23] supplemented by local surrogate-assisted tuning, a set of alternative geometries representing available compromises between the circuit bandwidth (to be maximised) and footprint area (to be minimised) are obtained.…”

Design and Analysis of a Stub-Less Capacitive Loaded Branch Line Coupler With Improved Bandwidth Performance

“…For wideband applications, a microstrip patch is investigated as an alternative for the BLC in [14] and further explored in [15] and [16]. The structure of the patch is deformed in [16] with spline-based geometry, for which significant improvement in bandwidth is achieved, but the size remains large.…”

“…For wideband applications, a microstrip patch is investigated as an alternative for the BLC in [14] and further explored in [15] and [16]. The structure of the patch is deformed in [16] with spline-based geometry, for which significant improvement in bandwidth is achieved, but the size remains large. A coupler based on half mode substrate integrated waveguide (SIW) is explored in [17], which achieves a wide bandwidth with a rapidly varying phase difference between output ports.…”