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The UHF antenna for the Skynet communications satellite comprises a circularly polarized helix radiator. In the CAL design (Fig, 1), the helix conductor is realized as an aluminum tape conductor supported at one end by an extendible structure designated as the bistem. This central conducting tube, along with a set of longitudinal support tapes, allows the helix to be deployed in orbit. At the base...
The original ideas which lead to the development of MMP-3D are still very much in use. However during the past years, there has been some recent improvements which lead to both the hybridization and generalization of the method. In particular, there has been a generalization for the sources or basis functions, to allow the computation of special geometries. Also, a combination with line theory has...
This paper presents a coupling of two different methods for electromagnetic scattering problems, the 3D MMP (Multiple MultiPole) code, an implementation of the Generalized Multipole Technique (GMT) and the finite element (FE) method. The coupling is performed by iterative methods. The procedure is illustrated with the solution of benchmark problem for scattering from a three-dimensional lossy dielectric...
A new direct method for solving general systems of linear algebraic equations originated by the author is applied to the repealed solution of a given system when changes of some rows occur in the system matrix. Such repeated computations are needed in numerous practical problems, e.g. in various imaging devices (electromagnetic, acoustic, etc.) or in linear optimization. The solution method is based...
Electromagnetic field scattering problems can be solved by either an analytical or numerical method. With the advancement of computers, the numerical method has lately received a lot of attention. However, in some aspects, an analytical method can still offer certain advantages over the numerical approach. This includes a better physical insight into the problems and a better computational efficiency...
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...
Most phenomena is interpreted by its special differential equations and relating boundary values. Mathematically in order to interpret the phenomena, we consider the wave function(ψ), Wave functions derived from the original differential equation of the phenomena. General space part spherical wave function is:, (▿2+k2)ψ=0, where ψ= ψ(r,θ,ϕ) in spherical. The equation can describe diverse phenomena...
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...
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.
Future satellite based, personal communications systems operating in the 20/30 GHz frequency range will require small and reliable RF components capable of being manufactured in large quantities. Suitcase sized terminals are expected to be available and phased array antennas appear to be an attractive way of realizing the necessary planar antenna configuration. Integrated circuit technologies such...
Advancements in microstrip technologies have made possible the development of many miniature multilayered integrated devices, for various antenna and microstrip circuitry applications. The use of a coupling slot (aperture) in these devices is a recent method utilized for coupling electromagnetic energy from one substrate layer to another. This technique generally involves the use of a rectangular...
Propagation characteristics of uniplanar structures consisting of slotline and coplanar waveguide are studied using an enhanced spectral-domain approach. Numerical results are presented for design consideration of various slotlines and CPWs on alumina and GaAs substrates. Effects of structural parameters on characteristics are discussed.
This paper describes a model for a GaAs/AlGaAs Heterojunction Bipolar Transistor (HBT). The model is based on the Gummel-Poon topology with modifications to account for self-heating and transit time effects. The model is capable of predicting the DC and small signal S-parameters from 1–40GHz. The simulated and measured load pull characteristics showed a 1–2dB discrepancy.
Three V band and one Ka band low noise amplifier designs have been completed using a GaAs PHEMT process. The two-stage Ka band device demonstrated a 23 dB gain with a noise figure of less than 3,7 dB over the 26 to 33 GHz range. The V band designs have achieved their respective simulated bandwidths of 2, 7 and 10 GHz, Though full testing of the wide band designs has not been completed, the two-stage...
Passive 180° phase-shifters (rat-race or monolithically integrated equivalent) have usually a frequency bandwidth narrower than an octave. A differential amplifier structure provides a very large operating bandwidth, and allows an easy MMIC integration.
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...
It is shown that the equivalent input noise current density of a travelling wave front-end of an optical receiver can be improved by using a combination of large gate line matching impedance and series inductive tuning. A MMIC travelling wave front-end utilizing these design considerations is experimentally shown to have a 8 GHz bandwidth and an equivalent input noise current density 8 pA/√Hz.
Rick Cassell has 19 years experience working with MLS. He has extensive experience in analyzing MLS integrity and continuity of service. He has worked for the last ten years as an advisor to the U.S. representative on the International Civil Aviation Organization All Weather Operations Panel. He has a Bachelor's Degree in Electrical Engineering from Villanova University.
A generic antenna model which simulates various MLS antenna configurations is described. The performance of the user specified antenna is analyzed using the MLS type parameters such as Effective Radiated Power (ERP), Mean Angle Error (MAE), Filtered Raw Angle (FRA), Control Motion Noise (CMN) and Path Following Error (PFE). Other parameters such as beamwidth, beamshape, dynamic sidelobe level and...
A simple cavity resonator is described for measuring surface resistance (Rs) of high temperature superconductor (HTS) thin films. The cavity is a one-half wavelength of WR-28 waveguide with the HTS forming a short across one end. A choke ring reduces the need for low resistance contact. Quantitative Rs measurements can be made over the range of 10 mΩ to 500 mΩ at liquid nitrogen temperature and at...
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