Open AccessDesign of planar diplexers with improved isolation using the tunable transmission zeros of a dual‐mode cavity filter
Author(s) -
Khan Arani Ali,
Mandal Mrinal Kanti
Publication year - 2017
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.2016.0692
Subject(s) - diplexer , planar , dual mode , dual (grammatical number) , transmission (telecommunications) , filter (signal processing) , electronic engineering , transmission line , isolation (microbiology) , topology (electrical circuits) , control theory (sociology) , computer science , telecommunications , engineering , electrical engineering , computer graphics (images) , art , literature , microbiology and biotechnology , control (management) , artificial intelligence , biology
A substrate integrated waveguide dual‐mode single cavity filter with two inclined slots on top metal plane provides two transmission zeros. It is shown that the feed offset as well as the slot offset both can be used to tune the zeros over a wide range of frequencies. Leakage loss from the slot is negligibly small. Two bandpass filters are fabricated to validate the predicted zero variation. Further, tunability of the zeros is utilised to greatly improve the isolation characteristics of two X‐band planar diplexers. Measurement results show that the isolation is better than 30 dB even if the channel separation is as close as 5% of the average frequency. The effect of packaging on the filter characteristics is also presented.