Compact substrate-integrated waveguide bandpass rat-race coupler and its microwave applications

• Published in: IET microwaves, antennas & propagation Vol. 6; no. 9; pp. 1000 - 1006
• Main Authors: CHENG, Y. J, FAN, Y
• Format: Journal Article
• Language: English
• Published: Stevenage Institution of Engineering and Technology 19.06.2012; The Institution of Engineering & Technology
• Subjects: Applied sciences; Bandpass; Bandwidth; Circuit properties; Design engineering; Electric, optical and optoelectronic circuits; Electronic circuits; Electronics; Exact sciences and technology; Frequency filters; Joining; Microwave circuits, microwave integrated circuits, microwave transmission lines, submillimeter wave circuits; Microwaves; Oscillators, resonators, synthetizers; Radiocommunications; Simulation; Telecommunications; Telecommunications and information theory; Transceivers; Transmitters. Receivers; Waveguides; Direct convertor; Return loss; Substrate integration; Butler matrix; Compact design; Waveguide; Transceiver; Ring structure; Frequency characteristic; Magnetic coupling; Band pass filter; Magnetic structure; Frequency response; Cavity resonator; Miniaturization; Coupled resonator
• ISSN: 1751-8725; 1751-8733
• DOI: 10.1049/iet-map.2012.0011

A reduced size rat-race coupler, incorporating a bandpass frequency response characteristic, is presented and designed based on substrate-integrated waveguide (SIW) technology. By use of electric- and magnetic-coupling structures between adjacent SIW cavity resonators, a conventional rat-race coupler and a bandpass filter with a 200-MHz bandwidth at a centre frequency of 7.75 GHz can be integrated as one component resulting in miniaturisation. A design process based on the coupled-resonator network is introduced to synthesise such a bandpass coupler with desired bandwidth, return loss and coupling. A Butler matrix and a six-port junction with bandpass response are then developed based on the proposed rat-race coupler. They represent excellent candidates for miniaturised transceiver and direct conversion systems. The measured results are in good agreement with the simulated predictions.