Research On Testing Technology Of Material Complex Permittivity Of P-Band

With the development of electronic technology,the importance of electrical properties of materials in P-band has increased in biomedicine and other fields.The complex dielectric constant is an important parameter to characterize the electrical properties of materials.Nowadays,network parameters method and resonace method are the main testing methods.But both methods have limitations in P-band,the lower accuracy of network parameters method and the fewer points of resonance method.However,for most liquid materials and biological media,the complex permittivity changes with frequency in the P-band obviously,it is difficult for resonance method to test with few resonance points.In order to test the complex permittivity of P-band,the existing methods and research status were analyzed,a reentrant coaxial cavity resonant testing system with intensive multi-frequency point testing capability working in P band was designed.Meanwhile,the physical model of the cavity was studied theoretically,the field distribution of the cavity was analyzed by simulation software and a system was integrated.Based on the mode matching method and the equivalent circuit method,an algorithm was given to reduce the influence of the sample hole.In order to change the resonance frequency of the cavity,a disturbance block was designed,and the stepper motor was used to control the disturbance block's movement to get more frequency points.An automatic test software of perturbation method was given to realize automatic extraction of measurement parameters,automatic calculation and storage of complex permittivity.A variety of solid and liquid samples were used to test the validation of test systems,and the errors were analyzed.The experimental results show that the system can not only test the electrical parameters of biological media and liquid materials in the P-band,but also test the solid materials in aerospace,electromagnetic shielding and other fields,which have great demand for P-band testing.The measurement range and the measurement errors of the test system are as follows:Test frequency:90MHz?1GHzTest range:?r?:1?30;tan?:0.005?0.5Test error:Single point:|??r?/?r?|?4.0%,|?tan??|?10%tan??+2×10^-3Dense points:|??r?/?r?|?4.5%,|?tan??|?15%tan??+2×10^-3...