High-Isolation and Wide-Stopband SIW Diplexer Using Mixed Electric and Magnetic Coupling

• Published in: IEEE transactions on circuits and systems. II, Express briefs Vol. 67; no. 1; pp. 32 - 36
• Main Authors: Su, Zhi Li, Xu, Bo Wei, Zheng, Shao Yong, Liu, Hai Wen, Long, Yun Liang
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2020; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Apertures; Cavity resonators; Coupling; Couplings; Diplexer; Diplexers; high-isolation; Magnetic separation; mixed electric and magnetic coupling; Passband; Resonant frequency; Resonator filters; Stability; substrate integrated waveguide; Substrate integrated waveguides; wide-stopband
• ISSN: 1549-7747; 1558-3791
• DOI: 10.1109/TCSII.2019.2903388

In this brief, a high-isolation and wide-stopband diplexer with controllable transmission zero (TZ) nearby the passband, is implemented using substrate integrated waveguide elements. The TZ is generated by the mixed electric and magnetic coupling scheme of TE 101 mode. It can be flexibly controlled by changing the length of rectangular apertures while keeping good wide-stopband performance unchanged. An X-band diplexer with lower and upper channels centered at 9.5 GHz and 10.5 GHz was designed, fabricated, and measured to verify the proposed concept. Good agreement between simulation and measurement can be observed. The designed diplexer exhibits a high isolation level larger than 45 dB over the whole band and a wide stopband up to 20 GHz.