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A numerical algorithm has been developed for the analysis of cavity-backed spiral and slot antennas in a ground plane, in which the cavities may be arbitrarily shaped and may have discrete rotational symmetry. It also permits the treatment of inhomogeneously loaded cavities. The finite integral technique (FIT) is used to model the fields in the cavity [1]. The FIT is similar in many respects to the...
The analysis of microstrip structures has received a great deal of attention from many different researchers [1],[2]. Of particular interest is the Mixed Potential Integral Equation (MPIE) formulation as presented by Mosig and Gardiol [1]. This method exploits the continuity equation to develop an integral equation in terms of both surface current and surface charge densities. The solution scheme...
Recently, dielectric resonator antennas (DA) have been proposed as alternative radiators to the popular microstrip patch [1]-[3]. They have been demonstrated to possess characteristics similar to those of microstrip patches, i.e. low profile and compatibility with planar integration technologies, both desirable properties for future active phased arrays. However, they also have advantages over microstrip...
This paper presents computed data on the dispersion and loss properties of asymmetrical coupled microstrip lines with asymmetrically placed side walls. The computing method is based on mode matching technique. The computed data is found to agree very well with those obtained via the finite difference time domain method for the odd mode; and the difference is within six percent for the even mode. The...
Fixed coverage contour beam antennas for geo-stationary satellites can be obtained employing a shaped reflector illuminated by a single feed. Needless to emphasize, this offers a highly attractive alternative to reflector antennas illuminated by an array of feeds. The stringent specifications on the gain slope within the coverage contour and the isolation outside the coverage contour call for suitable...
An efficient method for the evaluation of singular integrals appearing in the analysis of electromagnetic scattering by arbitrarily shaped bodies modelled by triangular patches is presented. The derived expressions which are in closed form involve algebraic functions whose evaluation is not cumbersome and thus facilitate the ease of computations. In the proposed analysis, the Green's function is approximated...
In this paper, a simple cavity model is presented for the theoretical prediction of the radiation patterns of unidirectional dielectric radiator (UDR). The antenna structure is first modeled as a non-radiative dielectric waveguide (NRD) resonator, the electromagnetic fields at the radiating aperture of the antenna structure are then determined for the calculation of the radiation fields and patterns...
Coaxial lines are most widely used in driving microwave devices and antennas and in extracting outputs from them. In practice, both two processes involve a number of coaxial junctions which provide transfer characteristics dependent on the bandwidth of the microwave signal. Where transient characteristics of an antenna or any other device are to be investigated, the major prerequisite is to have a...
The floating exodus method is introduced. The Green's Junction in a center of a square with dielectric wedges is obtained. The probabilistic interpretation of Green's identity' is presented. The Shanks transformation is used to increase the convergency speed. The capacitance of a symmetrical stripline is obtained, and is compared with analytical solution.
The impedance method, which is a circuit representation of the finite difference method for quasi-static problems is applied to model induced electric fields and currents in biological cells exposed to 60 Hz magnetic fields. Two simplified representations of actual preparations used in laboratory studies are considered. These are: low and high density suspension of cells in a conductive medium. and...
The characteristics of a prolate spheroidal antenna, excited by a rotationally symmetric narrow slot, have been discussed by Wait [1]. Sinha and MacPhie[2] have discussed the admittance characteristics of an antenna system consisting of two symmetrically center-fed prolate spheroids in parallel configuration. Ciric and Cooray[3] have further investigated such two spheroidal dipole antennas in an arbitrary...
Input impedance of truncated coaxial cable is of considerable importance both from the calibration standard and non-destructive testing points of view. Significant effort has been expended in their analysis [1-3] in order to understand and exploit the fringing field effects. For a calibration standard knowledge of the fringing fields is essential to determine the additional frequency dependent capacitance...
In MIC's and printed antennas the dielectric substrates always have finite extent. Rigorous analysis of the truncation effects requires the solution of an integral equation with MoM. This is usually numerically intense especially for 3-D structures. In this paper the truncation effects are incorporated directly in an approximate Green's function. The Characteristic Green's Function (CGF) technique...
This paper describes parametric relationships that affect the design of high gain multibeam antennas, discusses tradeoffs, and presents optimized performance of two candidate antennas for wide-angle coverage Advanced Satcom: an aperiodic array with suppressed grating lobes and reduced number of elements, and a side-fed offset Cassegrain system with low scan loss. Given basic performance requirements...
In modeling antennas and their surroundings, or complex radar targets, configurations consisting of wedge structures are often involved. In several cases the wedge can be truncated close to its edge, and the truncation can also be characterized by a rounded boundary, even with a variable radius of curvature. This problem cannot be easily treated analytically; as a matter of fact only the simple problem...
Vertically directed radiation (ionospheric) properties of both the receiver and transmitter antennas used in the Cape Race Ground Wave Radar (GWR) are investigated experimentally as well as numerically. Using the radar system as the measurement tool, measurements were taken when a specially-built reference antenna in the form of a horizontal dipole replaced either the transmitting or the receiving...
The general problem of coupling through apertures has applications in slotted arrays, directional couplers, microstrip lines, etc. Numerous references are available in the literature, most of which use the Green's theorem to reduce the problem to an integral equation for the unknown tangential electric field in the aperture. Of these, the moment method is especially attractive because it inherently...
This paper describes the development of the EHF offset reflector antenna system for Personal Communications, Picoterminals. The picoterminal antenna system is an experimental unit designed for personal communications via satellite from any stationary location at an EHF band of 20/30 GHz. The antenna system consists of mechanically steered linearly polarized offset paraboloid reflector that uses a...
The ability to noninvasively measure high frequency signals at the internal points of an integrated circuit is important in performing diagnostics of current high speed microelectronics. Conventional measurement techniques rely on direct electrical contact with a point on the circuit being monitored. These measurements are limited to predefined test points and are difficult to perform without disturbing...
As telecommunications and radar systems are increasingly being designed to operate at higher and higher frequencies in the millimetre wave band, antenna designers have looked arrays, with feed networks based in microwave integrated circuit (MIC) technology, to meet the antenna requirements of these systems. Most of the research and design into arrays for millimetre wave applications has focused on...
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