Open AccessWideband arbitrary phase‐difference coupled‐line coupler with tight coupling coefficient and small phase variation
Author(s) -
Gao Liang,
Qamar Zeeshan,
Zhang Hong Lin,
Yong Zheng Shao
Publication year - 2018
Publication title -
iet microwaves, antennas and propagation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.555
H-Index - 69
eISSN - 1751-8733
pISSN - 1751-8725
DOI - 10.1049/iet-map.2018.5383
Subject(s) - phase shift module , phase difference , wideband , bandwidth (computing) , transmission line , planar , hybrid coupler , electric power transmission , phase (matter) , mathematics , optics , physics , power dividers and directional couplers , insertion loss , engineering , computer science , telecommunications , electrical engineering , quantum mechanics , computer graphics (images)
In this study, a planar arbitrary phase‐difference coupled‐line coupler having wide bandwidth, tight coupling coefficient, and small phase variation are proposed. The proposed coupler consists of two quarter‐wavelength coupled‐line sections connected with two different transmission lines. Moreover, the interconnection transmission line can be designed as a small phase variation phase shifter with the introduction of a shorted stub. The detailed theoretical analysis is provided to illustrate the design concept. The circuit parameters of this novel arbitrary phase‐difference coupler can be easily determined by the derived closed‐form equations. For verification, two 3 dB couplers with 45°/135° and 60°/120° phase differences are fabricated and measured. The 45°/135° coupler achieves 34.2% fractional bandwidth for 45° phase difference with 2° phase variation and 36.3% fractional bandwidth for 135° phase difference with 3.4° phase variation. Moreover, the 60°/120° coupler achieves 30% fractional bandwidth for 60° phase difference with 0.9° phase variation and 32.9% fractional bandwidth for 120° phase difference with 1.5° phase variation.