Modeling And Application Of Microstrip Cross-shaped Resonators

The microstrip Cross-Shaped Resonator is widely used in a variety of microstrip circuits for its simple structure.However with the frequency increasing,the center junction structrue will produce parasitic capacitance,affecting the final design results.In this thesis,after the modeling of microstrip Cross-Shaped resonator,the analytic expressions of parameters are deduced by the admittance matrix,and an improved method is given.Based on this,a Ku-band duplexer is developed for the radar netting,and the development of radar netting transmitter is completed.The main works of this paper are accomplished as follows:1.The equivalent circuit model of microstrip Cross-Shaped Resonators is established.To extract the parameters of the equivalent circuit model with high accuracy in ultra wideband,a method based on the admittance matrix is present.The closed formula is given,then verify the accuracy of the equivalent circuit model and analyze the parameters.2.In order to control the effect of the parasitic capacitance,two improved microstrip Cross-Shaped Resonators with concave and convex segments are proposed.Based on the investigation,the improved microstrip Cross-Shaped Resonators are applied to design DBR filters with center frequency of 14GHz and 16.5GHz.In order to meet the requirements of the radar netting communication system,the filters are connected by T-junction to make a Ku-band DBR microstrip duplexer.The 3dB relative band-width of the down channel(at 14GHz)is 7.3%and the 3dB relative band-width of the upper channel(at 16.5GHz)is 6.4%;the insertion loss in the passband is 2.4dB and 2dB respectively;the return loss is better than 14dB and 12dB;stopband rejection is higher than 50dB and the isolation is up to 60 dB.3.Based on the existing radar platform,a radar netting communication system based on 2FSK is designed,and the transmitter is completed.The LFMCW radar signal is transmitted in the upper channel of the transmitter,and the target information signal is transmitted in down channel.The communication channel uses 2FSK to modulate the baseband signal.After up-conversion and amplification,the modulated signal is connected to the transmitting antenna with LFMCW radar signal.Measured output signal of the diplexer meets the requirements well.