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A measurement technique to estimate dilute concentrations (1–5%) of metal inclusion in an inert dielectric is presented. Bulk permittivity of polymer metal composites with aluminium powder (1–5%) in epoxy indicated very small variation for the dilute mixtures. Reflection measurements from composites with small variation in bulk permittivity, Δε≈1 indicated an appreciable change in phase. Experimental...
A significant development in high voltage DC transmission technology can be observed, especially in last decade. In addition to design and construction issue, it is necessary to focus also on diagnostic tests during the operation. Electrical insulation systems under DC voltage are affected by degradation stresses, which have a negative impact on their reliability and proper operation. DC voltage is...
This paper presents complex permittivity of each layer of fully ripe palm fruit var. Tenera at frequency from 1 to 30 MHz. The complex permittivity data of palm fruit which can be described in terms of dielectric constant and loss factor is very crucial to design a radio frequency (RF) system for heating palm fruit. From our measurement, the characteristics of the capacitance, dielectric constant...
We give a physical bound on the product of bandwidth and attenuation per unit length for general electromagnetic band gap structures. The analysis is based on the Kramers-Kronig relations for the Bloch refractive index for a fixed direction of propagation through the crystal. The bound is given in terms of the low- and high-frequency asymptotes of the refractive index, which can be given simple estimates...
This work evaluates a formulation of the integral equations method to model the field pertubation introduced by a dielectric material in a radiofrequency field typical to a magnetic resonance imaging experiment. The approach incorporates the inhomogeneous body model into the Green's function. The accuracy of the Neumann series expansion is validated against the full numerical solution for different...
Recent investigations demonstrated that porosification of LTCC enables a local modification of material properties, in particular of the effective permittivity. These studies revealed that the electric field strength is highest at the lower conductor track edges on the porosified substrate. The local field strength peaks cause substantial influence on the effectiveness of permittivity reduction due...
This paper discusses numerical properties of volume integral equation formulations in electromagnetic scattering by isotropic, anisotropic and bi-anisotropic objects. The volume integral equation formulation written in terms of the volume current densities and discretized with element-wise defined discontinuous functions is found to lead to more robust and efficient solutions on a wide range of material...
This paper proposes a complementary multi-physics material analysis approach based on broadband dielectric characterization and Atomic Force Microscopy. In the prospect of integrated dielectric sensor design, this approach was applied to polymers commonly employed by various emerging technologies.
An adaptable measurement method is proposed for the frequency-dependency of the complex permittivity of the materials with low or high losses based on the rigorous hybrid electromagnetic method. Both transmission and reflection measurement methods are developed using the X-band waveguides. The validity of the methods is confirmed by virtual experiments and actual measurements.
This paper assesses the accuracy of a rectangular waveguide pierced by a tubular load sample holder for measuring liquid materials at high temperatures with a formulation based on Abdulnour's method. The measurement technique is derived from the transmission line method. The sample holder is adapted from a section of a rectangular waveguide pierced by a tubular load for high temperature measurements...
In the present paper we use the recently-proposed early-time GPR (Ground Penetrating Radar) amplitude technique with the aim of detecting the variations of electric conductivity in a porous material having a uniform permittivity. A specific laboratory setup has been realised to evaluate the sensitivity of the early-time amplitudes to the variations of the subsurface salt concentration (i.e., conductivity)...
The coarse and loose nature of unbound granular road materials presents a number of challenges for conventional permittivity characterisation approaches. An alternative that appears better suited to these materials involves measuring the phase-shift at discrete frequencies through a sample of known thickness. To validate this approach against more established methods, a comparison is required on materials...
This work addresses the need for a closed form expression to calculate the two dimensional (2D) conductivity of graphene that allows researchers to include graphene either as a 2D or a 3D material in their theoretical and numerical electromagnetic analysis. The closed form expression is developed based on the Kubo formula and experimental results found in the literature. Numerical studies reveal that...
We propose a fast and effective method for estimating the dielectric permittivity of pavement materials. The method is based on a transmission-line analytical model of the ground and on the use of a commercial ground penetrating radar (GPR) system. In order to verify its reliability and effectiveness, we apply the method for retrieving material permittivity of an actual airport taxiway pavement. We...
A dual-band cylindrical dielectric resonator antenna with varying permittivity in φ-direction for IEEE 802.11y and IEEE 802.11j systems fed by coaxial probe is proposed in this paper. The proposed structure is constructed using two different materials having different permittivites. In order to determine the performance of varying design parameters on resonance frequency and bandwidth, parametric...
This paper explores the effective permittivity and permeability of the structure which has periodic lossy dielectric objects embedded in a matrix. The asymptotic expressions for both high conductivity and quasi-static are derived and discussed. Numerical results both from the MG formula and an integral equation approach are provided to verify all the asymptotic expressions and related conclusions.
A novel UHF RFID temperature sensor tag is designed using solid temperature-dependent material. A lightweight HDPE-BST material is first developed, whose permittivity decreases as ambient temperature increases. Using this material as the tag antenna substrate, a simple slotted patch sensor tag is then designed, fabricated, and measured. The experimental results show that an 8MHz/10°C frequency shift...
The feasibility of a core-shell particle to mimic the behavior of an RLC circuit is examined. In particular, under the quasi-static limit, the conditions are derived that allow for this type of particle to exhibit a high-impedance and a high-admittance response. These conditions dictate that the core and the shell are comprised of material characterized by positive and negative permittivity, respectively...
An SAR image-based technique to obtain geometry and constitutive parameters information about low permittivity lossless dielectric materials is presented. While characterization of high permittivity dielectrics is relatively affordable in SAR images, the lower power reflected back by low permittivity objects makes their characterization a challenging task. The proposed technique combines two illumination...
A new approach for measuring dielectric constants at RF frequencies (30–300MHz) is proposed. The proposed method utilizes the parallel plate test fixture and retrieves permittivity based on a radial waveguide mode. It is verified by simulation, and moderate accuracy (<10%) is obtained. This method can be a complementary approach to other conventional ones which are available for lower or higher...
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