Design of a miniaturized branch line coupler using common defected ground structure

Abstract

A design of size-reduced 90 o branch line coupler (BLC) is described in this work. A common defected ground structure (CDGS) is adopted to design the coupler. Common DGS patterns are realized on the common ground plane of double-sided microstrip lines of which ground planes are attached to each other back-to-back. The CDGS patterns play a great role in size-reduction of microwave circuits. As an example, a BLC is designed, fabricated and measured at 1GHz for the verification of the size-reduction using CDGS. The size of the fabricated coupler is less than 50% of the normal one without any critical degradation in performances. The measured Sparameters well agree with the simulation results.

Recent Developments of Butler Matrix From Components Design Evolution to System Integration for 5G Beamforming Applications: A Survey

“…To achieve these functions, the λ/4 wavelength transmission lines of the conventional couplers are usually converted into their equivalent circuits according to the specific design and operations. It can be obtained by equating the ABCD matrix of the traditional transmission line's ABCD matrix to the desired coupler design [37]. For the conventional transmission line section in Fig.…”