Design of Band-Pass Microwave Filter Based on Metal Micro-Coaxial Structure

With the gradual maturity of 5G technology, the structure design and performance optimization of microwave filters have become one of the important research topics in the field of RF communication. In this paper, the metal micro-coaxial structure is used to design a bandpass filter with a center frequency of about 28GHz. The structure form of short transversal line is adopted, the order is 5, and the 3dB bandwidth is about 20.3%. In-band insertion loss is greater than -1.19dB, The out-of-band suppression is less than -47dB and -30dB in the frequency band larger than 38GHz and smaller than 18GHz, respectively. The voltage standing wave ratio at the center frequency is 1.0512. The metal micro-coaxial structure provides a high isolation degree for the filter, and the insertion loss is smaller than the same type of filter, which has good engineering application value.