Microstrip multifunctional reconfigurable wideband filtering power divider with tunable centre frequency, bandwidth, and power division ratio based on three‐parallel‐coupled line section

Abstract

A compact microstrip multifunctional reconfigurable filtering power divider (FPD) is proposed based on varactor‐loaded three‐parallel‐coupled line section (TLCS) in this letter. Continuously tunable third‐order filtering power division response with two transmission zeros (TZs) including centre frequency (CF), bandwidth (BW) and power division ration (PDR) is successfully attained by varying the external and internal coupling through loading varactors into a three‐parallel‐coupled line topology. For validation, a prototype is implemented. The results indicate that the CF can be tuned from 0.46 to 0.8 GHz, a tunable 3‐dB BW of 80 to 190 MHz is exhibited with better than 17‐dB return loss and higher than 15‐dB in‐band isolation. In addition to the CF and BW tunability, the power division ratio (PDR) for the presented FPD can also be adjusted from 1:1 to 1:5. Additionally, a compact size is realized with only 0.12λg × 0.16λg.