The Study Of Miniaturized Microstrip Dual-band Bandpass Filters

At present,with the emergence of various wireless communication technologies,the communication system including multiple communication technology is becoming a hot topic of concern.As one of its key components,the filters that can operate in multiple frequency bands can effectively filter out noise or unwanted signals,reducing circuit size and insertion loss.Therefore,the study of multi-band filter is the focus of the current research.In this paper,miniaturized microstrip dual-band passband filter is studied.The main work includes the following.1.The resonant characteristics of the SLR are analyzed,and the relationship between the resonant characteristics and the key structural parameters is revealed.On this basis,two kinds of stub loaded resonators are constructed.By selecting the appropriate coupling structure and feeding method,two adjustable dual-band filters are constituted.In order to show the design process,the equivalent circuit is derived and the mechanism of generating transmission zeros is analyzed.And finally the actual processing and testing is carried out.The test results demonstrate that the center frequencies of the two passband of the filter are independently adjustable and have a large adjustment range,which indicates strong flexibility and adaptability.2.Using a combination of step impedance resonator and uniform impedance resonator,a dual-band filter is constructed.In order to reveal its physical mechanism and establish the equivalent circuit,the coupling mechanism of two pass bands and the mechanism of producing transmission zeros are analyzed.The final test results verify the corresponding analysis,which suggests the dual-band filter has excellent frequency selectivity and out of band rejection and the circuit size is small.3.A new type of resonator with "double loop connection" is studied.Through the electromagnetic simulation,the relationship between the structural parameters and its resonant frequency can be revealed.In addition,choosing the appropriate coupling structure and feed structure,then a dual-band filter is completed.The test results manifest that this filter has excellent out-of-band suppression characteristics.