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For many liquid materials and biological media, their complex permittivity varies with frequency in the P-band (100–1000 MHz). In this paper, a re-entrant coaxial cavity resonance test system with intensive multi-frequency points testing capability is designed for the P-band to realize the test of the complex permittivity of P-band materials. For this system, a test algorithm has been written, and on the basis of this system, a perturbation block has been designed, using stepper motors to control the up and down movement of the perturbation block to achieve frequency tunability of the cavity, enabling more P-band frequency test data to be obtained. The experimental results show that the system is suitable for testing the electrical parameters of P-band biological media and liquid materials and for testing solid materials in aerospace, electromagnetic shielding, and other fields where there is a great demand for P-band testing.

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The variation law of equivalent dielectric properties of sandwich hole-core structure materials are investigated based on the analysis method, where the hole-core structure can be three kinds of structures, such as square, hexagon, and circle. Considering the hole-core structure is anisotropic, the calculation method of the electromagnetic parameters on the sandwich hole-core structure wave-transmitting materials are first derived. The accuracy of this method is validated by a numerical example of a plane wave incidence on a sandwich hole-core structure materials in free space. In addition, an S-parameter inversion method is proposed to calculate the equivalent dielectric and the results using phase-compensated to solve the inaccurate calculation of the dielectric around the S-parameter half-wavelength resonance. Finally, according to this model, the equivalent dielectric constant increases with increasing the incident angle for transverse electric (TE) polarized wave incidence and transverse magnetic (TM) polarized wave incidence, while an opposite phenomenon occurs for TE polarized wave incidence and TM polarized wave incidence on equivalent loss tangent.analysis method, sandwich hole-core structure wave-transmitting materials, The variation law of equivalent dielectric properties How to cite this article: Qin L, Yu C-Y, En L, Tu Y-H, Long J-W. Study on dielectric properties of electromagnetic wave oblique incidence on sandwich hole-core structure wave-transmitting materials.