A compact square dc-block bandpass filter with slots is presented. The proposed dc-block bandpass filter using square shapes produces compact size and improved performance as compared to the conventional dc-block bandpass filter using cymbal shapes. Two filters with the same dimensions provide different center frequencies respectively. In other words, the center frequency of the square bandpass filter is lower than that of the cymbal bandpass filter. The center frequency and transmission zeros can also be controlled by the slots of the square shape in the proposed square bandpass filter. The proposed square bandpass filter has an insertion loss of better than 2 dB and a return loss better than 10 dB at center frequency of 7.2 GHz. The proposed square dc-block bandpass filter is optimized by electromagnetic simulator IE3D.
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