Design of a novel suspended substrate stripline highpass filter

In this paper, a new type suspended substrate stripline highpass filter with simple structure is presented. The filter consists of 50 ohm input and output, one Y type short stub on the top layer and two similar to T type short stubs on the bottom layer. It will introduce coupling capacitances by put sheetmetals close to each other. The coupling capacitances and inductances will compose the series resonators to produce transmission zeros. Thus the filter has a good restraint outside the passband. The simulation has a good result. The passband is from 5 GHz to 25 GHz, insertion loss is greater than −2 dB and return loss is less than −12 dB. At the same time, there are two transmission zeros at the low frequency.