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     

An E-field integral equation solution for the radiationfrom reflector antennas with struts

The E-field integral equation is applied to rotationally symmetric reflector antennas with struts. Current is allowed to flow on all the reflector surfaces and continuity is enforced at the conductor junctions. Radiation patterns are presented for a small paraboloid antenna, and the effects of the struts are clearly defined. These include the strut cone radiation, pattern asymmetries introduced by the struts, and gain loss and sidelobe level changes     

Mutual coupling in a slotted phased array, infinite inE-plane and finite in H-plane

The mutual admittance matrix is computed for a planar phased array of thin slots with assumed single-mode cosinusoidal aperture electric field. The array is of infinite extent in the E-plane and of finite extent in the H-plane. The H-plane excitation is arbitrary and the array is phase scanned in the E-plane. Resultant active row-port admittances and H-plane aperture distribution are in agreement with large strictly finite array calculations and with a Floquet mode infinite array model, for the example case of uniform H-plane excitation     

Superconducting millimeter-wave E-plane filters

The authors report on the measured performance of a three-pole E-plane filter constructed from high-T_c superconducting bulk materials at 34.5 GHz. Experimental results are presented for the insertion loss and return loss of the filter at 77 K. The problems associated with the use of bulk materials at the millimeter-wave range are addressed. Other possible superconducting waveguide filter configurations are proposed. While the experimental results are taken at low input power level, the current distribution inside the filter structure is calculated, and the power handling capability of the superconducting filter is discussed     

H-polarization diffraction by a thick metal-dielectricjoin

An analysis is presented of the H-polarization diffraction due to a material discontinuity formed by the junction of a thick dielectric half-plane with a metallic half-plane having the same thickness. This is accomplished by first considering the solution of several subproblems. These include the direct diffraction and coupling due to a plane wave incident on a loaded open-ended parallel plate waveguide and radiation and reflection by a waveguide mode. The final solution for diffraction by the metal-dielectric join is obtained by introducing a perfectly conducting stub within the loaded guide and subsequently using the generalized scattering matrix formulation with the stub brought to the waveguide opening. All the analysis relating to the subproblems is done by the dual integral equation approach. As expected, the final expressions involve several Wiener-Hopf split functions which are evaluated numerically or analytically     

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     

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     

E-plane scan performance of infinite arrays of dipolesprinted on protruding dielectric substrates: coplanar feed line andE-plane metallic wall effects

The effects of coplanar feed lines and of E-plane cavity walls on the performance of infinite arrays of dipoles printed on protruding dielectric substrates are investigated. In order to do so, two unit cell configurations are studied: (1) the dipole element fed by coplanar transmission lines and (2) the dipole element fed by coplanar transmission lines with finite-height metallic walls added parallel to the H-plane of the array. The element active impedances are calculated for these configurations, and they are compared with those obtained from arrays of dipoles without coplanar feed lines. Effects of the dielectric substrate permittivity and of its thickness on the array element active impedance are included. The results show that the arrays of dipoles with the coplanar feed lines exhibit feed-line-induced blindnesses which reduce considerably the scan volume of the array. It is also shown that these feed line effects are reduced for thicker or higher permittivity substrates, and that the insertion of electric walls is one possible avenue for eliminating these anomalies     

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     

Diffraction of an H-polarized electromagnetic wave by a circular cylinder with an infinite axial slot

A comparison of three methods of solution for the problem of scattering and diffraction of a transverse electric (TE) polarized plane wave by an infinite circular cylinder having an infinite axial slot is presented. In one method of solution, the aperture field integral equation (AFIE) method, the fields in and around the cylinder are found from the apertureE-field and the Green's functions for the interior and exterior of a cylinder. In the other two methods, the fields are determined from the surface current, which is obtained by solution of theH-field integral equation (HFIE) or theE-field integral equation (EFIE). The field in the aperture of the cylinder is found from the three methods, and the advantages and disadvantages of each method of solution are discussed. In addition, it is also shown that for shell thickness less than 1/20 of a wavelength, the aperture fields do not differ signifcantly from those of an infinitely thin shell cylinder.     

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     

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     

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     

Microstrip linear slot array antenna for X-band

The X-band microstrip slot antenna array is described as an attempt to achieve moderate bandwidth and overcome the problems of radiation from microstrip feed lines and surface waves in the dielectric. The discussion covers development of a mathematical simulation that computes the radiation pattern of a single microstrip slot and the feeding microstripline; construction of a uniform broadband microstrip slot antenna array; development of a mathematical simulation that computes the radiation pattern in the H- and E-planes; and investigation of the mutual coupling between the slots. A comparison is made between computed and measured results at X-band frequencies     

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     

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