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The finite-difference time-domain technique (FDTD) is used to model electromagnetic systems with lumped elements. The FDTD equations are modified to account for the presence of lumped elements such as R, L, and C and current or voltage sources inside the grid. FDTD equations that include nonlinear elements, i.e., diodes and transistors arc derived.
This paper presents the analysis of a via hole contact between a microstrip and stripline for potential applications in multilayer antennas. A full-wave analysis based on the 3D-TLM method is used to model the transition. The effect of the via and the clearance hole shape and size were discussed. Simulations obtained using this analysis were compared to the measured data.
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...
The second flight unit of the Italian telecommunication satellite (ITALSAT F2) will embark an L-band multicarrier payload for European Mobile Service (EMS) replacing the 40/50 GHz experimental propagation package presently in orbit with ITALSAT F1. The EMS payload has introduced the passive intermodulation (PIM) products problem into the Italsat spacecraft previously not designed to be PIM free. This...
In this presentation a detailed discussion on the measurement of microwave permittivity of dielectric slabs and surface resistivity of thin films are given. A new needle-type coaxial probe with improved performance is also described and evaluated.
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...
Relationships are presented for use in determining material properties of dielectric objects, including permittivity, density, moisture content, and mass, from measurements of frequency shift and change in cavity transmission characteristics when a small object is inserted into a microwave resonant cavity. Results are presented for such measurements of moisture content of individual soybeans and cereal...
This paper describes the measurement and computation of the resonant frequencies and the associated Q factors of dielectric parallelepipeds made of high-permittivity, low-loss ceramic materials. The radar cross-section(RCS) is measured separately near each resonance peak with a fine frequency step. A curve-fitting method is used to accurately estimate the resonant frequency and the 3 dB bandwidth...
With increasing application of millimeter wave integrated circuits (mm-ICs) in radiometry, radar, astronomy, and communications, more accurate design data for various waveguide structures are becoming necessary. The majority of the millimeter-wave integrated circuits is based on the printed transmission lines such as suspended microstrip lines [1], fin lines [2] and non-radiating dielectric (NRD)...
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...
In this paper the finite difference time domain (FDTD) method is employed to model and predict the radiation patterns of a bent-slot half-wavelength dipole on a rectangular conducting box. Radiation patterns obtained using the FDTD are compared well with published results.
The loop antenna is well known as a fundamental element that radiates a linearly polarized wave. Recently, some unique properties have been discussed for a loop antenna capable of radiating a circularly polarized wave (CPW) [1]-[4]. CPW radiation is obtained using two perturbation elements on the loop.
In this paper we study the mathematical modelling of a domestic microwave oven with incorporated metallic bars. These bars act like antennas. They are powered by the microwave energy that excites the oven and transmit the energy to the surface of the lossy load (see figure 1). The calculation of the field inside the cavity and of the external characteristics of the cavity as seen by the source guide...
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...
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...
Cylindrical dipole antenna is the basic element in antenna and scattering analysis. Here, a symmetrical cylindrical dipole antenna analyzed and measured by, 1) Analyzed by MM (Moment Method) based on NEC (Numerical Electromagnetic Code), 2) Analyzed by a separate M M program based on PWS (Piece Wise Sinusoidal) basis and PWL (Piece Wise Linear) base function. 3) Measured a typical monopole over RF...
Automatic picture transmission of real-time meteorological conditions to aircraft via satellite is receiving increasing attention in numerous applications, from improving flight efficiency to search and rescue. Currently, they are a number of satellites that provide such a capability. In Canada, most of the required information is in the northern regions and the best satellite information is not from...
The effect of imperfections in terms of surface roughness which could lead to the introduction of air gaps between the dielectric resonator (DR) and the contacting conducting surfaces is investigated. Results of studies which illustrate the effect of air gaps upon the input impedance and resonant frequency of cylindrical dielectric resonator antennas (CDRAs) operating in the TM01 and HEM11 modes are...
The CAL AMT-100 system provides communications capabilities for an aircraft. Via the Inmarsat series of L-band satellites, voice or data facilities (phone, fax etc.) are available globally on demand. The antenna for the system (Fig. 1) is housed in a tail-mounted radome, and is mechanically scanned in two dimensions to track the satellite.
Many attempts have been done to reduce the memory storage and computational time required by the integral equation method. Wu and Wu [1] employed the structure symmetry and periodicity to reduce the number of unknowns in the problem. Nabors and White [2] presented a general 3-D capacitance calculation program called FASTCAP. Although the computational time have been reduced significantly, the storage...
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