Design Of The Hairpin Microstrip Bandpass Filter And Its Miniaturization Research

With the rapid development of mobile communication, at present, the fourth generation of mobile communication technology, the rapid development of China, the transmission receiving equipment have become increasingly demanding, microwave devices which has a very crucial role in these devices, the filter is also to development of high performance and miniaturization.Based on the theory first microwave filter will be explained. The use of an electromagnetic coupling theory of parallel coupled line based on a fifth-order design hairpin bandpass filter based on a 4003 Rogers as a medium. Through HFSS simulation, optimization choose the best performance dimensions. With Matlab programming indirectly determined variation of the filter size and performance. Then the above-mentioned filter prototype proposed structure of the two improved, namely open-loop issuers fifth-order filter and crossover issuers fifth-order filter. Two structures than the original filter dimensions are reduced by 26.5% and 34% of the area. But the three-band filters have emerged in the second harmonic. In order to better achieve integrated performance filter paper analyzes the defect ground structure DGS(Defected Ground Structure)of the basic theory, principles of use defect ground structure of the low-pass characteristic, is introduced into the DGS microstrip hairpin filters depth study of the impact of dumbbell-type defects in fabric filter for the overall performance of the designed filter has a very good harmonic suppression.Through the above analysis, processing six filter kind. Net loss of use of the filter test, get test results and simulation results were analyzed, it was found the test results and simulation results filter basically. Filter with the introduction of DGS and miniaturization in the back after the loss is less than-15 dB, and the effective band second harmonic suppression, can be used for the actual microwave transmission equipment.