Cross-Patch Dual-Mode Microstrip Bandpass Filter

Based on the configuration of traditional patch bandpass filter,a new and simple dual-mode bandpass filter using a cross patch with slot is presented in this paper. The cross patch resonator has an internal T-shaped slot connected through a square slot in the center,and their parameters are optimized. The optimized filter has two zero transmission points on both sides of the bandpass so as to improve its rejecting ability of stopband. Also the structure of the filter is miniaturized. Simulation of the presented filter found that the central frequency of its pass-band is at 2. 75GHz, the max return loss surpassed -32dB, the minimum insertion loss was 0. 6dB in bandpass and the 3dB bandwidth reached 59. 8%. It is confirmed that the experiment is in good agreement with simulated results.