Scattering of H-polarized waves from conducting strips inthe presence of an electrically uniaxial half-space-a singularintegrodifferential equation approach

Electromagnetic scattering from perfectly conducting infinitely long strips in the presence of an electrically uniaxial half-space is treated analytically. A uniform H-polarized plane wave is incident from the isotropic region. As a prerequisite to this approach, the H-mode scalar Green's function of the structure is developed. Its use in connection with the reciprocity theorem leads to a singular integrodifferential equation for the current density induced on the scatterer surface. The equation is solved for strips parallel or perpendicular to the interface, located above or embedded in the anisotropic region, following a special technique based on the theory of singular integral equations that has been developed in connection with strips and slots and E- or H-polarized incident waves. Numerical results for the induced current density and for the scattered far field in a variety of cases are presented in graphical form. Whenever possible they are compared with existing results based on purely numerical procedures     

E-polarized scattering from a conducting rectangularcylinder with an infinite axial slot filled by a resistively coateddielectric strip

The potential use of resistive films for damping the resonance spikes observed in the radar cross section (RCS) spectrum of a partially open rectangular cavity is investigated using a recently developed finite-difference-time-domain (FDTD) method that utilizes the resistive-sheet boundary condition for the modeling of resistive films. Backscattering data obtained in the first resonant region for an E -polarized plane wave normally incident into the slotted side of the cavity are presented. It is shown that resonance behaviors can be eliminated completely with a low-resistance film that attenuates significantly the impinging wave. Poorer resonance damping performance is observed as the film resistance increases because more of the field is allowed to penetrate into the cavity. For the latter case, the presence of the resistive film lowers the Q-factor of the slotted cavity such that the resultant resonance spectrum is lower in strength and broader in bandwidth     

Scattering parameters of E-plane printed opposite fin inwaveguide

An analysis of the E-plane printed opposite fin in a waveguide is presented. The current distribution existing on the metal fin is obtained through a variational technique that utilizes the extremization process. The eigenvalue functions derived from the transverse resonance condition are used to include the effects of the dielectric layer. The computed data for a simplified case with Duroid substrate are compared with those obtained by means of the spectral-domain method. Based on the calculated results, a band-reject filter has been designed and tested at Ka-band. Good agreement on the filter response has been observed between theory and measurement     

Diffraction coefficients and field patterns of obtuse angledielectric wedge illuminated by E-polarized plane wave

The diffraction problem is treated for the incidence of an E -polarized plane wave on both interfaces of an obtuse dielectric wedge. Based on the dual integral equation, the total field is obtained by the sum of the physical optics solution and the edge-diffracted correction term. Calculated diffraction coefficients and field patterns are plotted in figures for a wedge angle of 120°, incident angles of 60° and 70°, and relative dielectric constants of 2 and 10. It is shown that the Neumann expansion to the nonuniform currents provides a more accurate correction to the physical optics currents than the multiple expansion as the angle of dielectric wedge increases     

Robustness of mean E{X} and R charts

The effect of nonnormality on E{X} and R charts is reported. The effect of departure from normality can be examined by comparing the probabilities that E{X} and R lie outside their three-standard-deviation and two-standard-deviation control limits. Tukey's λ-family of symmetric distributions is used because it contains a wide spectrum of distributions with a variety of tail areas. The constants required to construct E{X} and R charts for the λ-family are computed. Control charts based on the assumption of normality give inaccurate results when the tails of the underlying distribution are thin or thick. The validity of the normality assumption is examined by using a numerical example     

Computer-aided design of E-plane waveguide passivecomponents

The newly developed numerical analysis method for the inductive discontinuities in rectangular waveguides is presented. It can be used to analyze the scattering properties of E-plane uniform conductor-dielectric inserts in rectangular waveguides. These inserts are of arbitrary cross section and number. The calculation accuracy and speed are improved by a combined analytical-numerical approach. Some practical applications are given demonstrating its engineering usefulness     

Optimum design of waveguide E-plane stub-loaded phaseshifters

Broadband low-insertion-loss E-plane stub-loaded rectangular waveguide phase shifters are designed with the method of field expansion into normalized eigenmodes, which includes higher-order mode interaction between the step discontinuities. Computer-optimized three-stub prototypes of 90° differential phase shift with reference to an empty waveguide of appropriate length, designed for R140-band (12.4-18 GHz) and R320-band (26.5-40 GHz) waveguides, achieve typically ±0.5° phase shift deviation within about 20% bandwidth. For two-stub designs, the corresponding values are about +2.5°/-1° and 17%. Both designs achieve minimum return loss of 30 dB. The theory is verified by measurements of a compact R120-band (10-15 GHz) waveguide phase shifter design example milled from a solid block, showing measured insertion loss of about 0.1 dB and about +2.5°/-0.5° phase error between 10.7 and 12.7 GHz     

Spectral-domain analysis of E-plane waveguide tomicrostrip transitions

The spectral-domain technique and a residue calculus theorem are used to compute the input impedance of a microstrip transition to a rectangular waveguide. The transition consists of a printed circuit board inserted into a waveguide housing along the E-plane. The effects of the dielectric layer are considered in the present analysis. The behavior of the input impedance of the transition is studied with respect to the critical dimensions of the probe length and backshort location. Calculated results by the new formulation agree well with those computed using an integral equation and those measured at Ka -band frequencies     

Oscillators and amplifiers in integrated E-plane technique

An overview is presented of solid-state oscillators and amplifiers realized in E-plane technology. The circuit topology, basic design procedures, and performance characteristics are described and compared. Gunn oscillators, IMPATT oscillators, transistor oscillators, injection-locked Gunn oscillators, and transistor amplifiers are surveyed. Gunn and transistor oscillators have been realized successfully for frequencies from 10 to 110 GHz, thus covering almost the entire frequency range suitable for E-plane technology. IMPATT oscillators are difficult to design and to reproduce in quasi-planar form because of the high impedance ratio that must be overcome by the circuit. E-plane FET amplifiers have been built for frequencies up to 60 GHz     

Improved theory for E-plane symmetrical tee junctions

L. Lewin's theory (1975), which describes an E-plane symmetrical tee junction by an equivalent circuit with only three parameters, is examined. It is shown that although the theory is formally correct, its circuit parameters depend on the amplitudes of reflected waves. An improved theory corrects this fault     

p-i-n diode control devices in E-plane technique

The status of the use of p-i-n diode control devices in the E -plane technique, especially in integrated finline configurations, is reviewed. The circuit topologies, operating principles, and design considerations for state-of-the-art switches, attenuators, and digital modulators are discussed, and typical performance characteristics are presented. The superior performance of these components confirms that finline is the appropriate transmission medium for the realization of millimeter-wave p-i-n diode switches and attenuators in the low-power regime (up to some 10 W of CW power), where beam-lead diode devices can be used. By properly matching these devices to their finline embedding network, excellent broadband characteristics can be achieved     

E-plane analysis of a modified horn antenna withsuppressed far-out sidelobe level

It is shown that the far-out sidelobes of a horn antenna can be suppressed by curving the edges in the aperture. A three-dimensional uniform geometrical theory of diffraction (UTD) analysis of the E -plane radiation pattern of the modified horn antenna was performed and compared with straight edges. This analysis indicates that the curvature of the edges does indeed influence the sidelobes to the effect that the modified horn antenna has significantly lower far-out sidelobes. The radiation patterns for modified horns were measured and compared with the calculated patterns and were found to be in good agreement     

Computer-aided design of evanescent-mode waveguide filter withnontouching E-plane fins

The authors present a computer-aided design algorithm for the analysis and design of an evanescent-mode bandpass filter with nontouching E-plane fins. The theoretical analysis is based on the generalized scattering matrix technique in conjunction with the spectral-domain approach and mode-matching method. The technique used takes into account the dominant as well as the higher-order effects. The measured filter responses in the Ka-band are in good agreement with those obtained by this analysis     

Field theoretical treatment of E-plane waveguide junctionswith anisotropic medium

E-plane waveguide junctions containing an anisotropic medium are analyzed. The analysis is based on the equivalence principle and on cavity field expansions. Using the equivalence principle, magnetic surface currents are introduced at the imaginary boundaries chosen between the central region of the junction and the waveguides. The electric displacement D in the junction is expressed in terms of a solenoidal set and an irrotational set. Matching the tangential magnetic field at the imaginary boundaries leads to a matrix equation, the unknown of which are the amplitudes of the scattered waveguide modes. Using this method, the performance of E-plane waveguide junctions with full-height and partial-height ferrite post is analyzed. The influence of the completeness terms G_oq on the numerical results of an empty E-plane Y-junction is shown. The numerical results are compared with previously published experimental and theoretical results     

Analysis of E-H plane tee junction using avariational formulation

A three-port equivalent network for an E-H plane tee junction is determined taking into account the effect of waveguide wall thickness and considering the contribution of the dominant mode to the imaginary part of the self-reaction. The parameters of the three-port equivalent network are determined. From a knowledge of the equivalent network parameters, the net impedance loading, reflection coefficient, and coupling are evaluated for an E-H plane tee junction. A comparison between theoretical and experimental results is also presented     

Prediction of the E and H fields produced by theSwiss mobile EMP simulator (MEMPS)

The author discusses a simple analysis for determining the electromagnetic fields produced by the MEMPS simulator. A transmission line solution for the currents flowing on the simulator structure is obtained, taking into account both the resistive loading along the simulator and the dispersive nature of the earth under the simulator. Once the current distribution is determined, the fields at an arbitrary location are found by integrating the fields produced by an electric current element located over the lossy air-earth interface. Using this model, a procedure for estimating the fields at an arbitrary location within the simulator is described. This requires a knowledge of the primary transient E and H field components at a reference point near the simulator, or equivalently, a knowledge of the incident E or H field at this point. Results of this study indicate that it is possible to predict the simulator fields at other points, based on the reference fields and the calculational model     

Analysis of coplanar E-H planeT-junction using dissimilar rectangular waveguides

An analysis of a T-junction that differs from conventional H -plane T-junctions in that the T arm is rotated by 90° and coupling takes place through an inclined slot is presented. Since use of standard X-band waveguides results in such a T-junction operating above 11.7 GHz, nonstandard waveguide dimensions have been considered to bring down the operating frequency to 9.375 GHz. The effect of a change of the broad dimension of the primary feed waveguide on the resonant conductance is evaluated. The variations of resonant length with the angle of inclination of the slot, and coupling with frequency, are presented     

A complete E-plane analysis of waveguide junctions usingthe finite element method

A complete finite-element analysis of inhomogeneous E-plane waveguide junctions is presented. It is shown that at least two field components are needed for the analysis. This method solves for the three components of the magnetic field in two dimensions and calculates the scattering parameters of the junction. Precalculated matrices are used for fast matrix assembly. Results for a metallic post agree very well with earlier published values. A dielectric post was also analyzed     

The E-parallel polarization response of a two-dimensionalheterogeneous layer modeled by two thin sheets

The flexibility of the thin-sheet technique for modeling two-dimensional structures is extended by analyzing the response to E-parallel to the strike of the anomaly polarization, also known as the transverse electric (TE) mode, when a heterogeneous Earth is modeled by two thin sheets over a horizontally stratified half-space. The electromagnetic fields induced by the heterogeneous layer when a uniform plane wave is normally incident on the Earth are expressed as integral equations, which are then evaluated using the method of moments. The resulting matrix equations are solved by the Gauss-Seidel method, and the magnetotelluric impedance is calculated