2018 Volume 15 Issue 8 Pages 20180234
A broadband bandpass filter with a dual-plane structure is proposed. The dual-plane structure consists of a pair of L shaped microstrip feed lines on the top layer and a triple-mode defected ground structure resonator (TMDGSR) on the bottom layer. Electric field distributions and frequency response of the TMDGSR are investigated. A sample filter using TMDGSR with a 31.9% of 3-dB relative bandwidth at the centre frequency of 3.6 GHz is fabricated and measured. The simulation and measurement results show that the TMDGSR has some advantages such as: simple compact triple-mode resonator structure and broadside coupling with feed lines easily, which are very useful in broadband DGS BPFs design.