Wide bandwidth arbitrary phase difference branch line coupler. Issue 9 (September 2017)

• Record Type: Journal Article
• Authors: Qamar, Zeeshan; Chan, Wing Shing; Derek, Ho
• Is Part Of: Microwave and optical technology letters. Volume 59:Issue 9(2017:Sep.)
• Page Start: 2241
• Page End: 2245
• Publication Date: 2017-09
• Subjects: arbitrary phase difference -- phase compensation network -- 3‐dB branch line coupler; Microwaves -- Periodicals; Optics -- Periodicals; 621
• DOI: 10.1002/mop.30716
• Languages: English
• ISSNs: 0895-2477

Abstract

Abstract: As a conventional branch line coupler (BLC) is limited to a phase difference of 90°, different phases have typically been realized by cascading additional phase‐shifters, which inevitably increase the circuit size. This article presents a BLC capable of achieving a combined wide bandwidth and arbitrary phase difference. This is achieved by inserting a phase compensation network directly in each of the series branch lines, which effectively modifies the electrical lengths. A prototype 60°/–120° coupler has been fabricated and experimentally characterized to achieve a 0.5‐dB magnitude imbalance, 5° phase stability, return loss better than −15 dB, and isolation better than −14 dB from 2.3 to 3.5 GHz.