A WR-3 dual-band bandpass filter based on parallel coupling structure

A WR-3 dual-band bandpass filter based on micromachining fabrication process is presented in this paper. The topological structure of the dual-band filter is formed by a pair of parallel coupled single-band bandpass filter and two T-shaped matching stubs. While each single-band filter is designed by Chebyshev 6-stage inductive obstacle structures. Then the dual-band filter is fabricated and measured. The results show that the dual passbands have about 7 GHz downwards shift than the designing. The rectangle coefficient of the dual passbands is 1.33 and 1.42, respectively. The return loss of the proposed filter is better than 14 and 12 dB while the insertion loss is around 3.6 and 7.1 dB. The whole size of the fabricated filter is about 21 mm x 11 mm x 1.48 mm. It demonstrates a practical way to design, fabricate and measure the dual-band filter working in terahertz range with good rectangle coefficient.