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In this paper a computationally efficient method of moments (MoM) formulation is presented for the full-wave analysis and design of radial line slot antennas (RLSAs). The method efficiency is based on an ad-hoc representation of the internal problem (electrically large circular cavity) Green's function, which is split into the sum of a parallel plate waveguide contribution and a rim effect contribution,...
A radial line patch antenna (RLPA) with external feeding phase control is presented. The coupling mechanism from the radial waveguide to the patches is achieved by inner small microstrip lines. The fed amplitude is controlled by the dimensions of these lines, whereas the phase is modified by outer transmission lines. The coupling internal lines are also placed in order to minimize the mutual reflections...
A broadband and compact antenna concept for a point-to-multipoint communication system at millimeter-wave frequencies is presented. The antenna consists of a rectangular feed waveguide, an H-plane parallel plate horn, an enclosed parabolic reflector section, a radiation slot aperture, and corrugated external baffles. The bandwidth is 2.9 GHz corresponding to a relative bandwidth of 12.6 % at 23 GHz...
This paper presents a numerical and experimental verification of an approximate integral equation technique for modeling thick slots. The approach is based on a perturbation method and modified Green's functions that take into account the finite metallization thickness. The method is in principle independent of the slot environment and has been already applied to aperture antennas, but can be used...
The paper presents application of channel simulation according to statistical Saleh-Valenzuela model for a typical university building architecture. Estimation of parameters is based on analyze of measured power delay profiles, obtained in measuring campaign inside the same building. The vector network analyzer method of measuring was applied, inside 1600 - 2000 MHz frequency band. All measurements...
Multiband behaviour of the rectangular linearly polarized broadside radiated microstrip patch antenna (MPA) modified by one and two stage T-notch shaped perturbation elements has been studied with the help of planar simulator IESD. Explanation of physical multiband behaviour providing broadside radiation of MPA is done via description of surface current distribution at selected resonance frequencies...
The paper discusses the method for determining radiation pattern of an array mounted on a conical structure. Two types of antenna elements are considered: waveguide openings and microstrip patch antennas. The analysis method is based on the modal representation of the EM field, i.e. the solution procedure takes advantage of representing the fields as a sum of spherical harmonics with unknown amplitudes...
One of the most recognised and renowned methods of excitation of waveguide consists of a small coaxial-line, terminated in the centre of the broad face of a rectangular guide ,with its inner conductor extending a certain distance (d) into the guide. This is the simplest and the most practical kind of excitation, thus, sufficient evaluations and contours of its matching to a variety of cables have...
In this work, we present a method of calculation of the high frequency electromagnetic field HF at the surface of a massive screen. This method is formulated in magnetic potential vector by taking into consideration the quasi stationary harmonic mode. We used the finite element method to solve the problem in the structure and the method of integrals of border in the external medium, which can be extended...
In recent years, the miniaturization of antennas became more and more important, especially in connection with subscriber transceivers for cellular systems. Due to the multiple scattering environments and the almost indefinable operating scenario, the crosspolarization characteristics of the antenna are less important, however its physical size is critical. The attempts to reduce the physical size...
In this paper we present design trade-offs of array architectures for hemispherical coverage. We show that a spherical array geometry is the optimal choice for this application in terms of performance and cost. It is a natural array geometry that provides scan-independent hemispherical coverage with a uniform gain pattern. We also show that a spherical array requires fewer elements than a comparable...
Archaeological heritage objects are influenced by the environmental parameters, which can modify their structure and composition. In many cases interventions are urgent in order to stop or slow-down the degradation process. The aim of this work is to illustrate a non invasive technique of disinfesting works of art. The suitable devices and the different phases of the project are briefly described...
A wideband electric field probe based on the diode detector connected to a low-pass filter is analyzed here. This circuit is analyzed using a linear-nonlinear analytical approach, and the transfer function is given for small and large signals. It is shown that the fiat response is expected above the cut-off frequency, which is defined differently for small and large signals. The cut-off frequency...
This paper presents a PSP (patch with a ring slot and conducting pins) antenna. Using the FDTD method, the PSP antenna is designed to radiate a linearly polarized conical beam over a wide frequency range. The design is performed in three steps. In the first step, a center-fed patch above a ground plate, referred to as the original patch, is analyzed. It is found that the reactive component of the...
In this paper we propose a dielectric lens antenna configuration for radar sensor applications in order to overcome the difficulties related to interconnection and feeder losses of antenna array needed to increase the directivity of radar system. Here the directivity is increased by a single curvature dielectric lens collimating the radiation from a single patch. The resulting radiation and matching...
A new method for the design of matrix distributed amplifiers is presented. The method is based on using the parameters of a predesigned low pass filter for the design of the matrix distributed amplifier. It is shown that using this method, characteristics of the matrix distributed amplifiers can be improved. Using the proposed method two new matrix distributed amplifiers are designed and their characteristics...
Modern radio-communications have begun the transition process from analog to digital radio-communications and broadcasting. During this transition process, main changes are required in exciter units of transmitters. The architecture of transmitters themselves is the same for both digital and analog broadcasting, but the exciters used for digital broadcasting have to create analog RF exciting signals...
A methodology for simulation of InSb MOSFETs in standard drift-diffusion simulators is presented. Due to its low bandgap and high mobility, InSb shows promise as a material for THz active devices operating at very low voltages. Non-parabolicity, degeneracy, mobility and Auger recombination/generation are explained and modeled. Leakage current, transconductance and maximum unity current gain frequency...
The esterification involved in durable press (DP) finishing is one among several chemical reactions that can be improved by microwave radiation. Cotton material is usually esterified with modified 1,3 dimethylol 4,5 dihydroxyethylene urea (DMDHEU). In this study, a novel microwave planar device was used for simultaneous drying and curing processes. The device was constructed at the Department of Textile...
In the present work, a plasma antenna is characterised for the application in the VHF range. An efficient network for plasma generation, and a feeding network for the VHF signal are presented, together with the results of measurements and simulations on the structure. Comparison between a traditional metallic antenna is also presented. The switched on time of the plasma is measured to look into the...
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