Khona Garb

The behavior of the electromagnetic field near the edge of a resistive half-plane

The authors define the behavior of the electromagnetic field near the edge of a resistive half-plane, taken separately, as well as in conjunction with a perfectly conducting halfplane. The efficiency of accounting for the established field behavior while finding the solution of boundary problems of electrodynamics is illustrated by computational results. >

Analysis of longitudinal slots in ridged waveguides using a hybrid finite element-Galerkin technique

A hybrid approach, combining the finite element method (FEM) with an integral equation formulation of the tangential electric field, is developed for the solution of longitudinal slots cut in the broad wall of finite thickness of a ridged waveguide. The system of integral equations formulated at both interfaces of the slot, is solved using the Galerkin approach with sinusoidal basis and testing functions. The Greens function for the internal waveguide region, as called for in the integral equation formulation, is generated numerically, utilizing the eigenvalues and eigenfunctions of the waveguide as computed by the FEM with Lagrangian fourth order polynomials. This approach is quite general, allowing for arbitrary waveguide cross sections and compositions. Computations of the dot characteristics performed in this way agree very well with previously documented as well as our own experimental results. >

Characteristic impedance of a rectangular double-ridged TEM line

The characteristic impedance of a TEM transmission line, shaped as a double-ridged rectangular coaxial line, is analyzed in this paper as the customary transversal static problem. This type of transmission line is useful, for example, as a part of a cascaded transition between a double-ridged waveguide and a coaxial line. The solution of the transversal problem is achieved by dividing the cross-sectional region into distinct, separable regions, each one being characterized by closed-form Greens functions relating the flux function to the electric field. Surface-type integral equations are then formulated over the boundaries between the regions. Solution of these equations via the method of moments (MoMs) using the Galerkin choice yields the results for the characteristic impedance as a function of cross-sectional dimensions. Convergence of the solution is also studied.

Waveguide E-plane folded cross-coupled filters

Folded E-plane cross-coupled waveguide filter topologies provide high selectivity by virtue of their transmission zeros. A design method for these topologies is presented below. The method is explained in physical terms and is validated by both simulations and experiments.

Edge conditions for the junction of two resistive half-planes with different surface impedances

This work presents an analysis of the behavior of an electromagnetic field near the common edge of two resistive half-planes with different surface impedances. Unlike a single resistive half-plane, in the case of the impedance junction, both transverse electric and magnetic fields components simultaneously contain a logarithmic singularity. It was shown that a surface current density has a finite jump that is proportional to the difference between the inverse impedances.

Design of E-plane T-junction dividers using substrate integrated waveguide (SIW)

Power dividers/combiners are critical building blocks of Solid State Power Amplifiers (SSPA). We propose a novel E-plane power divider with arbitrary splitting ratios, implemented in SIW technology. The divider is realized on standard dual layered PCB substrates, where the required coupling is achieved through a slot between the two layers. This unique design can be subject to easy modifications that support arbitrary power split ratios. Both equal and non-equal K-Band power splitter prototypes have been designed, fabricated and tested. Simulation and experiments validate the performance of this very useful building block for future miniature SSPAs.

Mode matching analysis and design of waveguide E-plane filters and diplexers

Implementations of wireless techniques call for low return and insertion losses and high slope selectivity of mm wave devices. Not many structures potentially satisfy all of the above criteria. In this work, diplexers with E-plane filters combined with an H-plane Y-junction splitter are investigated. The Y-junction configuration of the splitter is chosen based on its favorable S-parameter behavior. Filter analysis is facilitated using the mode matching technique (MMT). Based on this analysis, a band pass filter for the K band was built and tested. In order to integrate the filters with the Y-junction, the filters are positioned appropriately along the junction arms. The integrated filter-junction structure was then analyzed by an MMT code for the entire structure. An integrated diplexer model was built and tested, confirming the predicted performance based on the MMT.

Microstrip bandpass filters based on coupling matrix with second harmonic suppression

An approach for suppressing the second order harmonic responses in open loop resonator bandpass filters is presented. A known technique for the effective suppression of even-mode harmonic responses is based on loading the open loop resonator at its center with a resistor. A basic analysis of this structure leads to the conclusion that the even-mode resonance is controlled without affecting the responses at the odd-mode resonant frequencies. More detailed simulations, however, that take into account the size of the resistor via hole and the substrate losses, reveal that the value of the resistor has significant impact on the overall response, including fundamental odd-mode. In particular, the insertion loss in this mode becomes worse. By replacing via holes by open stubs with quarter-wavelength length at the even frequency, we have managed to achieve better rejection level in the even-mode with affecting the low insertion loss in the fundamental mode. Experiments verify the simulated predictions.

Multimode harmonic power meter for circular overmoded waveguide at second and third harmonics

A device for measuring the power of higher order harmonics in circular waveguides is presented. The device is constructed of several single-mode TEM waveguides (typically coaxial cables) which are coupled to the circular waveguide. Coupling is implemented by means of small inclined slots. Based on a technique of statistical analysis for the power coupling coefficient averaged over all coaxial lines, the total power of the higher order harmonics can be estimated. A uniform statistical distribution of the amplitudes of high order modes is assumed, from which the mean value, standard deviation and probability density function for the averaged power coupling coefficient can be found.

TE/sub 10/ mode scattering by a rectangular resistive film of arbitrary dimensions placed along the rectangular waveguides axis

Transverse electric (TE)/sub 10/ mode scattering by a resistive film of arbitrary width (d) and length (l) placed in the longitudinal section of a rectangular waveguide parallel to its narrow faces is investigated. The vector integral equation for the discontinuity of the tangential magnetic field on the film is formulated. The equation is solved by the Galerkin method using basis functions, each of them taking into account the discontinuity behavior near the film edge. For a film that is sufficiently short (l >