Research On The Test Method Of Complex Dielectric Constant Of High Frequency Plat

With the rapid development of microwave technology,high-frequency plates have been widely used in aerospace defense,biomedicine,microwave communications,remote telemetry and other fields.The complex permittivity is one of the important parameters affecting the performance of high-frequency plates,and the accuracy of the complex permittivity of the plates and the uniformity of distribution will have an important impact on the performance of microwave circuits.The microwave resonance method has high test sensitivity and has been widely used in the measurement of complex permittivity.Therefore,a test method combining resonant loop circuit and transmission line circuit is proposed and designed for high-precision measurement of the dielectric constant of high-frequency plates at frequency points of 2 and 10 GHz and the uniformity of the dielectric constant in the distribution of plates.The main research contents are as follows:Based on the test principle of resonant loop and transmission line,a test method for measuring the dielectric constant of high-frequency plates by combining resonant loop circuit and transmission line circuit is proposed.In order to improve the test accuracy,transmission efficiency and suppress the interference of spurious peaks,the resonant loop circuit and transmission line circuit are optimized for design.Then the influence of the change of the resonant ring structure parameters(average radius,ring width,coupling gap)on the resonant frequency of the resonant ring is analyzed.Aiming at the problem that the calculation error of the resonant ring formula is too large,the correspondence between the resonant frequency and the dielectric constant around 2 and 10 GHz is obtained by high-precision scanning simulation.Measured analysis of resonant ring circuit and transmission line circuit processing.Aiming at the problem caused by ink coating on the test of resonant ring circuit during plate processing,the influence of ink thickness on resonant frequency was studied.The test of the reinforced coupled shielded resonant loop circuit shows that the error between the relative permittivity simulation and the measured is within ±0.007,and the performance of the resonant loop circuit with wide test frequency band,effective suppression of stray waves,efficient transmission efficiency and high test accuracy is verified.The test of grounded coplanar waveguide transmission line circuit shows that its performance is good,the loss tangent accuracy obtained by this method is high,and the loss tangent error in DC-10 GHz is less than ±0.002.Based on the design of reinforced coupling shielded resonant loop circuit,two plate processing measurements were made with a domestic high-frequency plate as the main test object,and the error caused by plate processing on the test and the influence of the distribution of the intermediate electrical constant of the plate on the expected results were analyzed.The first plate processing test verifies the feasibility of resonant ring in product acceptance and production control of the control plate,and the second plate processing test analyzes the dielectric constant uniformity of a domestic plate,and compares and analyzes it with RO4350 B plate,and the results show that the dielectric constant distribution of RO4350 B plate is more uniform than that of a domestic plate.