Short Circuit Section Filter Technology

With the fast development of the technology, microwave and millimeter-wave systems are abroadly applicated in many fields, such as communication, navigation, telecontrol and electro-counterwork. For the limit of the frequency resource, the frequency channel distributed to multiple communication systems becomes narrow, and the wave band that used by the systems become higher and higher. Filter is the important part of the microwave and millimeter-wave systems, and is applicated in frequency selection. To meet the requirements of the systems, the filter have to own good frequency selectivity and harmonic suppression.The method of using shorting stub filter can be well applicated to solve those problems. Firstly, we introduced the process of the filter design and the shorting stub theory. The relationship between shorting stub's parameters and transmission zeros was analysed. We also analysed the capability of the shorting stubs with different coupling methods.Base on the theory, a FSS filter with shorting stubs was designed in this paper, and it realized good frequency selectivity with a compact structure. Then this structure was used to design an E-plane duplexer. At last, a band-stop filter with shorting stubs that works in V band is designed. Its center frequency is 8 GHz, and the width of the stop-band is 1 GHz. From those filters, we can see that the filter with shorting stubs can perform well both in band-pass and band-stop condition.