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Since the 1999 Korean scholars JIPark Defected Ground Structure ( DGS) , has been proposed , DGS structure has gradually become a hot research topic in the field of microwave and millimeter wave circuit design . And the photonic band gap structure ( referred PBG) similar to the DGS structure is also adopted in the ground plate of the circuit , etching a defective pattern , to change the distribution of the effective dielectric constant of the circuit substrate material , thus changing the effective inductance and the effective capacitance of the microstrip line , so that by the the DGS structure of microstrip line having characteristic impedances and bandstop characteristics . Therefore , DGS structure can be used to suppress the sub-harmonic of the antenna height and improved antenna gain and bandwidth , improve efficiency , and improve the Q value . DGS structure has the advantages of simple structure, superior performance and easy design and implementation , has been widely used in filters, splitters, duplexers and other microwave circuit . Microstrip antenna with light weight, small size, simple processing , conformal and many other advantages , a wide range of applications in the wireless communication system . Currently, many mobile communication devices , a dual-band microstrip antenna duplexer can save circuit space , the problem of mutual interference between the reception signals , and the microstrip antenna is easy to excite the higher harmonic drawback has limited the performance of the play of its greater . Firstly, using the simulation method to analyze the structure of the frequency characteristic of the two different shapes of DGS , and on this basis , using the neural network to be modeled as the input samples , the size and frequency of its structure , the HFSS simulation transmission the coefficient parameter sampling and sampling results as output sample , and then using the Bayesian regularization algorithm neural network training . DGS microstrip line circuit at the same time making the appropriate size measurement , measurement results and successful training of the neural network model calculation results are in good agreement illustrates the correctness and effectiveness of the neural network . Finally, the two different shapes of DGS structure is applied to the design of the dual-band microstrip antenna , and the simulation and the measurement of the actual circuit proved to successfully suppress the higher harmonic based on the the DGS structure of the dual-band microstrip patch antenna and improve port isolation .
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