Research And Design Of Switch Multiplexer

With the rapid development of wireless communication,Increasingly complex electromagnetic environment leads to a growing number of electromagnetic interference problems that can not be ignored,so the requirements for frequency selector are more stringent.In some special applications,due to the various application environments,it is impossible to ensure that the passband will not be interfered.At this time,it is necessary for the communication system to be able to switch and combine the passband flexibly to ensure normal communication in various situations.The VHF / UHF band switching filter multiplexer to be studied in this paper is to realize any combination output after frequency division of a broadband internal signal,so that the passband can be flexibly transformed to cope with various use scenarios.There is little research in this field at home and there are few materials available for research at home and abroad.In this paper,the development status and research significance of the switching filter multiplexer are summarized firstly,then the traditional filter design theory is studied and a VHF / UHF band-pass filter with free control of the out of band zero is designed based on the knowledge of out of band zero.Then,the design scheme of the multiplexer is studied from the point of view of matching network,and the combination of cascade and series characteristics of high-low pass filter is used The improved K-M filter designs a VHF / UHF band-pass nonadjacent Quad,and connects two bandpass nonadjacent quads embedded with each other through the characteristics of a power divider to realize the design of VHF / UHF band-pass adjacent octet.After that,a new method of mixed signal separation is proposed.The separation of two mixed signals with different frequencies is realized by using the same frequency inverse sub signals and the isolation network,which has certain practical value.At last,a dual channel single input and single output switching filter duplexer is realized by using the characteristics of reduced dual terminal filter and the function of switch frequency selection and isolation.It can not only realize the filtering characteristics of each channel,but also realize the superimposed passband filtering characteristics in combination.It can choose the output freely on threepassbands of 200 MHz ? 250 MHz,250MHz ? 300 MHz and 200 MHz ? 300 MHz,and reverse in passband The injection coefficient is less than-20 d B,the insertion loss is less than 0.2db,and the rectangular coefficient(50d B / 0.1db)is less than 1.4.The physical test results show that the passband is slightly offset and the insertion loss is large,but the expected function target is achieved,which has certain application value.