Abstract: In order to solve harmonic suppression, a parallel coupled line band-pass filter with simple structure was proposed. The filter consists of parallel coupled lines and open stubs. Filter's equation was firstly obtained via odd-even mode analytical method, which is based on the equivalent circuit of the proposed coupled line band-pass filter, and a compact band-pass filter was designed. Secondly, the relationship between filter's resonant characteristics and its electrical parameters was analyzed. And then, the geometric parameters of the proposed band-pass filter was obtained and optimized. Finally, the proposed band-pass filter and measured its S parameters was fabricated, which were basically consistent with simulation. It is founded that the filter designed has the advantages of simple structure, small size, etc. The proposed band-pass filter also has a wide stop band rejection and better selectivity through the introduction of transmission zeros.

Key words: bang-pass filter, parallel coupled line, open stub, odd-even mode analytical method, half wavelength