Method and system for testing microwave complex permittivity and complex permeability of materials

Abstract

The invention discloses a microwave complex permittivity and complex magnetic permeability testing method and system for materials, belonging to the field of microwave and millimeter wave testing. The method includes: obtaining the first input return loss of the sample material at the first testing position, And the second input return loss at the second test position; Calculate the sample transmission coefficient and reflection coefficient according to the functional relationship between the sample transmission coefficient and reflection coefficient and the first input return loss and the second input return loss, the The functional relationship is established based on the transmission line theory and boundary conditions; the complex permittivity and complex permeability are calculated according to the functional relationship between the complex permittivity and complex permeability and the sample transmission coefficient and reflection coefficient. Based only on input return loss S at different locations 11 The parameters are used to calculate the complex permittivity and complex permeability. The measurement beam can be either vertically incident or obliquely incident at a large angle. The problem of thickness resonance in the existing test method can also be avoided by controlling the test position.

Description

technical field [0001] The invention belongs to the field of microwave and millimeter wave testing, and more specifically relates to a method and system for testing microwave complex permittivity and complex magnetic permeability of materials. Background technique [0002] Multi-layer composites and structural materials containing periodic units have flexible electromagnetic parameter design and control characteristics, which can achieve better electromagnetic properties than traditional homogeneous materials, and have good mechanical properties. They have broad applications in radar absorption and other fields. application prospects. Accurate testing and characterization of the complex permittivity and complex permeability of structural electromagnetic functional materials has become a key point that urgently needs breakthroughs in this field. For the measurement of broadband electromagnetic parameters of materials, there are mainly coaxial line method, waveguide method an...

AI Technical Summary

Problems solved by technology

The terminal short circuit method can only determine the dielectric constant of the material, but cannot determine the magnetic permeability

The transmission-reflection method passes the input return loss S 11 and output return loss S 21 Two network parameters are used to calculate the equivalent complex permittivity and permeability of the material. This method can only be applied to normal incidence. When it is applied to oblique incidence, one transmitting antenna and two receiving antennas are required, and the transmission receiving antenna is due to the electromagnetic wave It is not easy to determine the position where the signal passes through the refraction of the material, and it is difficult to achieve a large angle of oblique incidence

In addition, both the transmission-reflection method and the terminal short-circuit method have thickness resonance phenomenon. The transmission-reflection method has a thickness resonance when the sample thickness is an integer multiple of the test half-wavelength, and the terminal short-circuit method has a thickness resonance when the sample thickness is an integer multiple of the test quarter wavelength. Resonance, affecting the accuracy of test results

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