Radiometric characteristics of snow in microwave frequency band.

This study investigates high-frequency magnetic, dielectric, and microwave absorbing properties of Sendust (Fe-Si-Al alloy) flake particles dispersed in rubber matrix for the design of thin microwave absorbers in quasi-microwave frequency band. At high particle loading (92% in weight) in the magnetic composite, reflection loss of -9 dB was obtained at 2 GHz with a small thickness of 1 mm. The result is attributed to the high values of magnetic permeability and dielectric constant of the composites resulting from a low eddy current loss (increase of permeability) of the flake particles and enhancement of space charge polarization (increase of permittivity) between the metallic particles. However, the investigation of impedance matching reveals that the magnetic permeability is still small to satisfy the zero-reflected condition at the quasi-microwave frequency band of 1-2 GHz with a composite thickness smaller than 1 mm. It is suggested that greater magnetic permeability (by control of composition and shape of magnetic particles) is required for more improved microwave absorbance at a quasi-microwave frequency.

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Thick volume hologram for microwave frequency band: Design, fabrication, and test

2004 10th International Symposium on Antenna Technology and Applied Electromagnetics and URSI Conference ◽

10.1109/antem.2004.7860689 ◽

2004 ◽

Author(s):

Jafar Shaker ◽

Apisak Ittipiboon ◽

Michel Cuhaci

Keyword(s):

Frequency Band ◽

Microwave Frequency ◽

Volume Hologram

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Research of Biological Effects of EM Field in Microwave Frequency Band

2019 PhotonIcs & Electromagnetics Research Symposium - Spring (PIERS-Spring) ◽

10.1109/piers-spring46901.2019.9017804 ◽

2019 ◽

Author(s):

Jan Vrba ◽

Jiri Kubes ◽

Ferdinand Trebicky ◽

Frantsiek Vozeh ◽

Jan Barcal ◽

...

Keyword(s):

Frequency Band ◽

Biological Effects ◽

Microwave Frequency ◽

Em Field

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NEW WAVEGUIDE METHOD FOR DIELECTRIC PARAMETER MEASUREMENT

Journal of the Russian Universities Radioelectronics ◽

10.32603/1993-8985-2018-21-5-33-38 ◽

2018 ◽

pp. 33-38

Author(s):

Andrey D. Grigoriev

Keyword(s):

Frequency Band ◽

Loss Tangent ◽

Measurement Techniques ◽

Microwave Frequency ◽

Reflection Factor ◽

Dielectric Parameter ◽

Practical Implementation ◽

Dielectric Parameters ◽

Waveguide Section ◽

Noise Component

Perfect knowledge of dielectric parameters is necessary for its application in various devices. In spite of the whole range of measurement techniques, their practical implementation in the microwave frequency band runs into some difficulties. This article describes a new method for nonmagnetic dielectrics permittivity and loss tangent measurement in the microwave frequency band. A dielectric specimen slab is placed in the short-circuited waveguide section normal to its axis and fills the whole cross-section of the waveguide at approximately quarter wavelength from its short-circuited endpoint. By means of the vector network analyzer the waveguide section reflection factor is measured. Objective function is de-termined as difference between calculated and measured module and phase of the reflection factor. Specific code for ob-jective function calculation and its minimization is worked out. Minimization of this function by varying dielectric parameters makes it possible to find real values of these parameters. The method needs no de-embedding and can be used with non-calibrated waveguide-to-coax transitions. Also it is less sensitive to the noise component of reflected signal. The testing results show that new method’s error does not exceed 0.2 % for relative permittivity and 1% for dielectric loss tangent.

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