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Study of Substrate Integrated Waveguide and Gap Waveguide technologies used to manufacture some demonstration prototypes at Ka band for a low losses distribution network in a low profile antenna. A transmission losses comparison is presented using lossy and lossless dielectric substrates in the simulations for the different technologies at 30 GHz. Various structures such as transitions from WR-28,...
This paper presents the performance of monopole plasma antenna. The plasma tube is used as radiating element. The antenna is designed and works at different frequencies. To couple electromagnetic signal from the coaxial probe to the plasma column, a coupling system is realized. It permit the tube to radiate in order to design a monopole antenna. The performances of the monopole are given in terms...
Purely passive, mechanically steered waveguide-fed horn arrays are good candidates to satisfy the current need for low-to-medium-profile antennas for mobile user terminals for SATCOM applications. In this work, a unique waveguide feed architecture is proposed, which enables the realization of grating lobe-free, wideband, low-profile waveguide-fed horn arrays operating with dual circular polarization...
The channel measurement and modeling of fading characteristics of 25.5 and 39.5 GHz bands in corridor environment are investigated. An automatic measurement system owning a sufficient dynamic range is designed to overcome the prominent attenuation in the millimeter-wave band. After conducting extensive measurements, large-scale and small-scale fading characteristics are obtained and compared. Good-of-fit...
Several studies have examined the propagation losses of the Human Body Communication (HBC) channel. However, a general agreement has not be found yet. In this paper, the complete S-matrix of the HBC channel is measured on an human subject using two kinds of electrode devices. The data is integrated in a lumped element model, which allows to take into account for the capacitive return path of realistic...
Clinical studies have established that adjuvant mild hyperthermia significantly increases the efficacy of radio-and chemotherapy across many tumor sites. Radiofrequency hyperthermia treatment quality is usually monitored with invasive temperature sensors, which provides limited data sampling and causes infection risks. To mitigate these issues, magnetic resonance (MR) measurements can be exploited...
The knowledge of the complex Radar Cross Section (RCS) of the human body in ultra-wide band can fully describe the breathing activity. In this paper, we investigate the time domain RCS so as to analyze the backscattered signal from the human body, for further respiratory monitoring in any aspect angle. The time domain RCS measurements are first calibrated with the monostatic radar measurement of a...
A method for the array characterization from Near-Field measurements is here presented. The method exploit the concept of Singular-Value Optimization to dramatically reduce the number of data needed by a complete mapping of the excitations. The approach is here applied to a planar scanning and numerically validated.
This letter presents a series-connected patches antenna aperture-coupled by substrate integrated waveguide (SIW), which produces narrowed E-plane beamwidth for improving antenna gain. With this special patch array, W-band multibeam array antenna capable of offering switchable beams in H-plane is designed by means of SIW Butler matrix. The simulation and experiment results show good impedance matching...
This work proposes the utilization of the Reflect Array (RA) antenna in the reader of the Frequency Coded (FC) chipless RFID systems aiming at increasing the reading range, minimizing the environmental reflections and acquiring a lot of novel capabilities that can not be provided by the conventional antenna systems. The FC chipless RFID system requires an UWB range of frequencies to accommodate multiple...
The efficient calculation of the Lattice Sums (LSs) for evaluating the free-space periodic Green's function (PGF) of an infinite phased array of line sources is addressed here and is extended for the first time to leaky waves. The method is based on the Graf's addition theorem for the 0-th order Hankel function that leads to an expansion in terms of Bessel functions of the relevant PGF. The coefficients...
Measurement of the radiation properties of low gain antennas at VHF frequency is in many cases a challenging task. Measurements performed in shielded anechoic chambers are usually preferred to outdoor ranges because they are not subject to the electromagnetic pollution and less affected by the scattering of the environment. However, different source of errors, such as truncation of the scanning surface...
The laboratory prototype of an UWB hyperthermia applicator is presented and tested for treatment of tumors in head and neck region. The focusing ability of the presented applicator for treatment of neck tumors has been tested on a homogeneous muscle phantom at 500 MHz. Two tumor positions were investigated: one in the center and one in the side of the mid-transverse plane of the phantom. The captured...
This paper investigates a low complexity high gain structure that can switch the radiation pattern from boresight to almost endfire direction. The principles of Fabry Perot, reconfigurable parasitic reflectors and partially reflective surfaces are combined to achieve the pattern reconfigurability. Two different Fabry-Perot cavity spacings are assessed and a maximum gain of 18.8 dBi is achieved at...
The design of a small printed-log-periodic antenna, loaded with an active matching network, for multiband applications is presented. A well-known, low-cost and low-profile antenna is re-engineered for including an additional impedance bandwidth in the lower UHF-band. The design method includes the use of the recently introduced sensitivity parameter Sens in order to find a suitable location for a...
A wireless channel is always composed of both deterministic and stochastic multi-path components. A high Rician K-factor increases the contribution of deterministic channel components, thereby reducing the significance of stochastic parts of a channel. This paper focus at the investigative analysis of K-factor and fading depth to analyze the deterministic behavior of a channel under a certain bandwidth...
We consider the utilization of higher-order basis functions, in the sparse processing framework, for brain stroke monitoring. Instead of retrieving the permittivity of the whole brain, the goal is estimate the variation of the electromagnetic parameters of the brain between two measurements. We assume that the differences in the measured electromagnetic field indicate the stroke evolution. Using average...
A recently published paper presented a novel concept for obtaining frequency reconfigurable behavior by combining multiple antenna elements and weighting the feed signals for each element. In this paper, we clarify some concepts presented in that paper and analyze the antenna structure in more detail.
In this paper, three experiments with coupled dipoles were carried out in order to determine the optimal distance where an efficient communication link can be established. The simulations results showed that when the subcutaneous dipole is installed adjacently to the surface of the skin, the dipole mounted above the skin level should be in the range of 20 mm to 25 mm for efficient communication. Subsequently,...
Recent use of measured data as near field sources in Computational Electro Magnetic (CEM) tools has opened the possibility to represent antennas in numerical simulations, even when the antenna characteristics and geometry are unknown and therefore cannot be included in a full wave model [1-4]. The near field source consists of an equivalent current representation of the antenna, which is prepared...
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