The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
The paper discusses the correspondence between electromagnetic boundary conditions and interface conditions. In particular, the focus is on the synthetic approach where the interest is in finding material realizations for given boundary conditions. Material realizations are approximative but not unique because, especially if anisotropic and bianisotropic materials are allowed, there are different...
In the classical Nicolson-Ross-Weir electromagnetic material parameter extraction technique the effective material parameters are obtained through reflection and transmission measurements of a planar material sample. One of the advantages of this technique is that it provides the result over a broad frequency band with just one measurement. This technique, however, does not provide us unambiguous...
An iterative transmission line technique for the determination of complex permittivity of non-magnetic, isotropic materials is addressed. The method is based on minimizing the objective function measuring the error between simulated and measured scattering parameters by classical Newton's method. An Electromagnetic field solver is used to solve the forward problem which is repeated in the application...
A particular UHF “miniaturized” antenna is presented in this paper. It is a kind of planar inverted F antenna (PIFA) which operates in a metal environment. The return loss of the antenna has been optimized over the ISM european frequency band (868 MHz). To reduce the size of the structure, the resonator has been folded under “itself” and a capacitive load is added in order to decrease the resonance...
A novel probe design form measuring complex permittivity of soils in-situ from 10 to 1000 MHz and above without taking soil samples is presented. The dielectric constant and conudctivity of soil is derived from step-frequency reflection taken inside a small (1∼2 inches) freshly bored holes. As a result, permittivity at various depths from surface with in-situ moisture content and soil texture can...
An approach to accurate permittivity measurements of compressible materials has been presented. The method uses both the measured, uncompressed density and the calculated, compressed density to account for the change in measured permittivity between compressed and uncompressed specimens of the same material. Normalizing susceptibility to compressed density provides data that closely agreed with actual...
Three approaches to numerical evaluation of two-dimensional Green's function under TMz polarization are studied for the Veselago Lens of finite and infinite extent. The first approach formulates the Green's function of the infinite lens in terms of Fourier integral which is subsequently evaluated numerically via direct integration along a modified path. The second approach extracts the dominant field...
The microwave furnace casting process is a time and temperature dependent nonlinear process. In this paper, we present our multi-physics modeling of a microwave oven process that is based on a coupled 3D EM- thermal analysis. Our efforts include the development of the necessary procedures and tools/probes to electrically and thermally characterize all utilized materials over a wide temperature range...
A cavity resonator and microwave heating system has been designed to measure the temperature dependent complex permittivity of dielectric materials in microwave frequency. To measure the temperature dependent complex permittivity of material, the output power of vector network analyzer is amplified to heat materials and obtaining complex permittivity by measuring transmission coefficient of cylindrical...
Dielectric permittivity is an important parameter for all investigations based on electromagnetic waves (e.g. GPR and TDR measurements). In combination with the electric conductivity, it is crucial for the determination of the propagation velocity, the reflection coefficient and the decay of the electromagnetic wave. The dielectric permittivity depends on several factors like water content, mineralogy,...
In this study, we present design and manufacturing technology for the Salisbury screen type radar absorbing structure (RAS) in X-band. The RAS is composed of a dielectric lossy sheet and an E-glass fabric/epoxy composite laminate as the spacer. This RAS has a broader absorbing bandwidth and much thinner spacer than those of the conventional one which uses a 377 Ω/□ resistive sheet for the impedance...
The methods of dielectric characterization at room temperature have been well-known for 20 years. Today regarding to the needs in the aerospace field, especially for the atmospheric reentry, radioelectrical measurements performed at high temperature are very useful. This paper introduces the test mean, denoted by EPSILON 1600 in the whole document, that allows characterizations of dielectric materials...
In this paper, we evaluate realizations for implementing an RFID reflected electro-material signature (REMS) sensor. REMS sensors allow passive measurement, recording, and reading of environmental data such as temperature in a small, low cost device. This paper presents results from two configurations: a three-section lossless microstrip transmission line and a monopole probe inserted into a lossy...
Organic dielectric materials will absorb moisture when in direct contact with a liquid or a humid environment. The dielectric then becomes a two-phase dielectric composite with new dielectric characteristics. Using the Lichtenecker Equation, the composite dielectric permittivity and loss characteristics are modeled. The loss modeling includes the polymer dielectric loss characteristics, as well as...
Electrically small antennas have remained a significant topic of interest for a number of applications, particularly low frequency systems and wireless networks requiring small devices. As is well-known, there are a number of techniques whereby an electrically small antenna can be efficiently matched to a 50 Ω system impedance. Ultimately, the primary design challenge is achieving as wide an efficient...
A generalized formulism has been derived from an equivalent circuit model for describing the effective permittivity of an artificial material composed of dumbbell-shaped metal particles embedded periodically in a host dielectric medium. Theoretical value of effective permittivity compare well with numerical results obtained from HFSS simulation. The work shows that artificial material can achieve...
Effective complex permittivity measurements of materials are important in microwave engineering and microwave chemistry. Artificial neural network (ANN) computational module has been used in microwave technology and becomes a useful tool recently. A neural network can be trained to learn the behavior of an effective complex permittivity of material under microwave irradiation in a test system and...
This paper presents the radiation characteristics and beam-width control features of a 2-18 GHz, cavity-backed, two-arm, elliptical Archimedean spiral antenna. We first discuss a precise microwave instrumentation and measurement technique to accurately characterize the frequency dependent complex permittivity and permeability of a wide variety of microwave materials. Using the method, we have designed...
In this paper, a new extraction method for the dielectric constant of PCB material is proposed, which is based on S-parameter inversion method. The calculation process is detailed and an application example is given. According to the simulated S-parameters, while with the proposed method, the applicable frequency ranges of a set of published expressions for microstrip lines are obtained. With the...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.