Design And Fabrication Of C-band High K Microstrip Ceramic Filter

In the era of rapid development of communication,the use of spectrum resources more and more widely,but also lead to the remaining available space becomes more narrow,applied to the RF field of high-performance filter research has become one of the current hot spots.Commercial communications and military communications systems offer some of the more stringent requirements for filter performance in meeting conventional conditions: high selectivity,low loss,and miniaturization.In the military communication technology,especially based on the ceramic substrate microstrip filter with low insertion loss,small size,high reliability,has received more and more attention.China's ceramic filter started late,and abroad to take a technical blockade,the study of high-quality ceramic microstrip filter has a wide range of prospects.In this thesis,the ceramic substrate material selection and preparation,microstrip filter design,simulation and physical processing and test results analysis.Firstly,the development status of the microwave dielectric ceramic materials used in the fabrication of the filter and the significance of making the ceramic substrate microstrip filter are introduced.The principle of the filter was analyzed and the ceramic substrate was selected.Finally,the MgTiO₃ xMgO-y(Ca_0.6-La_0.8/3TiO₃)microwave dielectric ceramic was used as the substrate material.The optimal microwave performance?x:y:=0.85:0.15?:?r=25.0±0.5,Q×f>50000 GHz?f=4.9 GHz?,?f=0±2 ppm/oC.In this thesis,the basic characteristics of the microstrip line were analyzed systematically.On this basis,the hairpin and interdigitatal band-pass filters were designed and modeled,simulated and optimized in Ansoft HFSS15.In this thesis,the parameters of microwave dielectric ceramics are simulated in Ansoft HFSS15,and the parameters under different values are studied,and the insertion loss and return loss performance of the filter are brought into account.At the end of this thesis,the simulation of the filter for physical processing and testing.Comparing the actual test results with the simulation differences,and analyze the reasons that may lead to these differences The results show:?1?the fourth-order hairpin filter test results center frequency was 4.18 GHz,4.2GHz offset than the point,the relative bandwidth of about 7%,with an insertion loss of3.2 dB,the upper edge of the external band with the simulation results almostConsistent at 4.8 GHz?| S21 |?attenuation is greater than 30 dB,low frequency attenuation at 3.6 GHz is greater than 30 dB,with in-band return loss?| S11 |> 13 dB?.?2?The fifth-order interdigital microstrip bandpass filter had a center frequency of4.2 GHz,a relative bandwidth of approximately 14% with an interpolation loss of 2.6dB,the upper frequency outside the stopband rejection is consistent with the simulation results,3.6 GHz | S21 | Value attenuation greater than 30 dB,4.8 GHz | S21 | value attenuation greater than 40 dB,while the in-band return loss is large?| S11 |> 11dB?.