Method of Accurate Design of a Microwave Band-Pass Filter Based on Adjust of Center Frequency

In this paper, the problem of excursion in center frequency of half-wavelength parallel-coupled line band-pass filter in traditional design is discussed.First of all, the basic principle of half-wavelength parallel-coupled-resonator filter is introduced, and the reasons for the deviation of center frequency are analyzed. Based on an approximately linear correction in center frequency,a parallel coupling band-pass filter with high performance working in X wave band is designed . The simulation results in ADS (advanced design system) approves the validity of this theory , in compare, the relative error between the theory and the optimal goal is less than 10%.