Research of Insertion Loss of Polycrystalline CVD Diamond within Range of 40...80 GHz

Insertion loss of polycrystalline CVD diamond within range of40...80 GHz is investigated by free space method. A diamond disk with diameter 56,6 mm and thickness 366 um was provided by GPI RAS. The disk was found to be radio transparent. Usage of diamond lid to seal LTCC package with T/R MMIC inside resulted in radiation loss by 2,9 dB at 60,5 GHz.

Study on space absorbing of multilayer MWCNTs/Fe3O4/NBR composites

In order to meet the requirements of “wide, thin, strong and light” for military stealth materials, it is of great practical value to study the absorbing characteristics of multi-layer MWCNTs/Fe3O4/NBR absorbing materials in space. First, we use the large-scale software COMSOL Multiphysics to simulate the absorbing characteristics of the composite thin plate in space. Then the four-port network matrix is used to calculate the absorbing characteristics of the composite plate in space. Finally, the Free-Space method is used to measure the reflection attenuation loss, and the results of the three methods are compared and analyzed. The results show that when the frequency is 10 GHz, the reflection loss of multi-layer MWCNTs/Fe3O4/NBR reaches the maximum value of −27.91, −27.01 and −22.56 dB by COMOSL numerical simulation, four-port network the matrix and Free-Space experimental measurement. The results of the three methods show that the reflection loss is less than −10 dB in the frequency band of 6–14 GHz.

Исследование потерь пропускания в поликристаллическом CVD-алмазе в миллиметровом диапазоне длин волн методом свободного пространства

Radio transparency of polycrystalline CVD-diamond disks with diameter up to 75 mm in millimeter-wave range was measured by free-space method. The structure of the disks was characterized by Raman spectroscopy and scanning electron microscopy. Dielectric loss tangent tan δ of the samples in the frequency range of 50 – 67 GHz was found to be in the range of 7.5·10−3 − 2.8·10−2, increasing with frequency. The transmission loss due to the radiation absorption is about 1%.

A Study of Electromagnetic Absorption Performance of Modern Biomass Wall Tile

Electromagnetic elimination was used to eliminate unwanted radiation that may interface with machinery or affect human health. The use of microwave absorbers has become necessary for an environment with a safe electromagnetic wave level. The objectives of this project are to design a microwave absorber as a modern biomass wall tile and to investigate the absorbing performance of the modern wall tile absorbers with different materials. The absorber was designed with similar shapes and different biomass materials. The concept of modern wall tile had been applied to design the absorbers in terms of their shape and dimension by using biomass materials. Biomass materials such as kenaf and coconut coir were used in the study due to their lightweight and environmental-friendly material behavior. The simulation was done using CST Suite Studio software to predict the preliminary result of the absorbers. The proposed designs of the modern wall tile from the CST simulation are then fabricated while the mixtures of the materials are moulded into a microwave absorber. NRL Arch free space method was used to determine the absorption performance of the modern wall tile absorbers at a frequency range from 1GHz to 12GHz. Both results of the simulation and free space measurement are analyzed and discussed. This study showed that absorber KCA has the best performance among all the absorbers with the absorption of more than -10 dB. The mixture of biomass material with carbon has a great absorption performance compared to the mixture of biomass material without carbon.

Characterization of the dielectric properties of water and methanol in the D-band using a quasi-optical spectroscopy

This work presents the measurement of the permittivities of water and methanol in the D-band. Water is a reference medium for dielectric measurement. The dielectric permittivity of water in the millimeter wave range is a fundamental parameter in many applications, and needs to be investigated systematically. The measurement is conducted using a quasi-optical spectroscopy, which is an improved free-space method more suitable for the millimeter wave range. The theoretical formulae are derived using the signal-flow chart method, which is developed specially for multi-layer operation. This model enables one measure liquid samples. A non-calibration method has been developed to retrieve the permittivity. Water and methanol are measured at several temperatures. The measured results agree with published results in a 4% discrepancy. This work will add new measured data to the permittivities of water and methanol over the whole D-band.