This paper studies the AC conductivity and permittivity of hydroxyapatite (HA)-based ceramics from 0.1 Hz-1 MHz at temperatures from room temperature to 1000 degrees C. HA-based ceramics were prepared either as dense ceramics or in porous form with interconnected porosity and were sintered in either air or water vapour. Samples were thermally cycled to examine the influence of water desorption ...

High permeability and high permittivity are hard to be achieved simultaneously, either in single-phased materials or in composite materials, such as ferrite-ferroelectric ceramic composites and ferrite-metal percolative composites. In this work, ultra-low percolation threshold is achieved in NiZnCu ferrite-Ag cofired ceramics, which endows the composite with both high permeability and high perm...

this paper presents a miniaturized open-ended rectangular waveguide antenna radiating below the cut-off frequency of the waveguide with a large bandwidth. Waveguide miniaturization is achieved by periodically loading the antenna with electromagnetic metamaterials consisting of infinity shaped resonators. The metamaterial cell is designed to have a high effective dielectric permittivity in the f...

In recent years, the transmission/reflection (TR) method has been successfully employed to determine the complex permittivity of dielectric material. Based on the principle that different coals have different abilities to absorb microwave energy at different frequencies, it is essential to analyze the electromagnetic property of coal to realize microwave desulfurization. Samples composed of a k...

Abstract—This paper presents the electromagnetic interference (EMI) shielding effectiveness of rice husk and carbon nanotubes (RHCNTs) composites in the X-band region (8.2-12.4 GHz). The difference weight ratio of carbon nanotubes (CNTs) were mix with the rice husk. The rectangular waveguide technique was used to measure the complex permittivity of the RHCNTs composites materials. The complex p...

In order to measure the dielectric permittivity of thin insulting layers, we developed a method based on electrostatic force microscopy (EFM) experiments coupled with numerical simulations. This method allows to characterize the dielectric properties of materials without any restrictions of film thickness, tip radius and tip-sample distance. The EFM experiments consist in the detection of the e...

Cavity perturbation technique is widely used in the measurements of complex dielectric permittivity of materials due to its accuracy and ease of configuration. This paper presents the theoretical formulas for the evaluation of complex permittivity of materials using cavity perturbation technique with substrate integrated cavity resonators. With the proposed formulas, the use of various planar c...

A novel complex structure of Printed Dielectric Resonator Monopole Antenna (PDRMA) with multi-bands operation is presented and investigated. In the proposed structure, a printed fork-like stepped monopole antenna is used for exciting two new modified hemicylindrical dielectric resonators with a great relative permittivity of 80. A narrow medium substrate with a low permittivity is also applied ...

When a planar dielectric medium has a permittivity profile that is an analytic function in the upper or lower half of the complex position plane x = x′+ ix′′ then the real and imaginary parts of its permittivity are related by the spatial Kramers-Kronig relations. We find that such a medium won’t reflect radiation incident from one side, whatever the angle of incidence. Using the spatial Kramer...

In recent years, the ground penetrating radar (GPR) is increasingly used in the detection of riprap embankments. In order to analyze the costal embankment with explosive compaction, model experiments are conducted to investigate the influence of seawater on the signal and image of GPR, especially to figure out the image variation of riprap bottom boundary. The influence of immersion of seawater...