Research And Implementation Of Planar Microwave Dual-wideband Bandpass Filters

With the rapid development of modern communication technology, wirelesscommunication systems have become an important driving force in the development ofinformation industry.As an important part of the wireless communication systems, microwavefilter can directly affect the performance of the whole communication system. In order tosatisfy the demand of different communication, modern communication systems need deviceswith multiband and broadband characteristics. Thus, research and develop dual-widebandbandpass filter with low profile and high performance is critically important. The thesismainly focuses on the design theory and circuit implementation technology of dual-widebandBPF. It is concluded as follows:Firstly, a dual-wideband bandpass filter based on stub-loaded resonator by using hybridmicrostrip and slotline is presented. A extremly wide-band BPF is achieved by using amicrostrip-fed stub-loaded multimode slotline resonator. Then a dual-mode stub-loadedmicrostrip resonator is loaded to the wideband BPF. As a result, a ultra wideband passband isdivided into dual wide-passband. Equivalent circuit model of dual wideband filter is givenand EM simulated results well agree with the theory ones. Then dual-wideband filter isdesigned, fabricated and measured. Measured results well agree with the simulated ones toverify the proposed theory. Bandwidths of two passband are49.6%and65.6%, respectively.Secondly, a dual-wideband BPF based on triangular loop resonator by using hybridmicrostrip and slotline is proposed. A wideband bandpass characteristics is generated by amicrostrip-fed stub-loaded multimode slotline resonator.Then the triangular loop resonator isloaded to the filter to achieve a stop band. Transmission model of dual-mode triangular loopresonator loaded slot line is given and analysised. EM simulated results well agree with theideal ones. Then a microwave dual wideband BPF with relative bandwidth of51.3%and48.7%is designed and fabricated for wireless communication.Finally, a dual-wideband BPF based on transversal signal interaction concepts ispresented. The theory of transversal signal interaction concepts is given. Transmission linemodel is given to control the position of transmission zeros and transmission poles. Then adual-wideband BPF based on transversal signal interaction concepts is designed. Relativebandwidths of two passband are73%and35%, respectively.