Periodically slotted dielectrically filled parallel-plate waveguideas a leaky-wave antenna: E-polarization case

The analysis of a periodically slotted dielectrically filled parallel-plate waveguide as a leaky-wave antenna for infinite and finite periodic structures for the E-polarization case is discussed. For the analysis of the infinite periodic structure, an integral equation in which Floquet's modes and the strip electric current satisfying the edge condition are used and Bloch wave analysis using the single-slot equivalent circuit parameters are employed. An integro-differential equation with moment-method and transmission-line analysis with equivalent circuit representation are used to analyze the finite N-periodic structure. Results of interest such as complex propagation constant and the radiation pattern for the finite slot number case are observed to be in good agreement with those of the infinite geometry case for the appropriately chosen values of slot numbers, slot width, period, and waveguide height     

Radiation characteristics of corrugation loaded dielectric-coated conducting cylinder

The radiation characteristics of a corrugation loaded dielectric coated conducting cylinder are investigated theoretically for the infinite periodic and finite structures. For the infinite periodic structure, the mode matching method is applied. The integral equation is derived for the finite structure by use of the Fourier transform and mode expansion. The influences of the corrugation width, corrugation depth, dielectric thickness, cylinder radius, and finite corrugation number on the radiation characteristics (leakage constant, phase constant, and radiation pattern) are investigated. The results of the finite periodic corrugations are compared with those of the infinite extent structure and good agreement is found. To reduce the high side lobe of the uniform periodic structure, nonuniform quasiperiodic corrugation arrays are considered. The surface wave radiated by the structure having end-fire radiation pattern is also investigated.     

Mutual coupling between parallel columns of periodic slots in aground plane surrounded by dielectric slabs

Arrays of slots with arbitrary orientation in an infinite conducting plane that are infinitely periodic in one dimension and finitely periodic in another dimension are considered. The plane is bounded on each side of dielectric slabs of finite thickness and infinite extent. Single columns of slots are represented by equivalent magnetic scattering currents, which are solved for by the moment method. The mutual coupling (admittance) between slot columns in the presence of the stratified media is found by the array scanning method, which expresses the admittance as the average of the scan admittance of an artificially constructed doubly infinite array of slots over all real scan angles. The technique avoids the use of Sommerfeld integrals, but still gives rise to singularities at scan angles corresponding to the resonant excitation of surface waves. An analytical approximation removes these surface wave singularities, making numerical implementation of the method practical     

用有限元—边界积分法研究有限壁厚矩形波导窄边斜缝

本文应用有限元－边界积分法研究有限壁厚矩形波导窄边斜缝导纳特性，该方法首先用等效源原理及镜原理建立缝隙表面磁场积分方程，然后把它们代人到缝腔中场满足的变分公式中，最后用有限元法求得缝腔中及口面上的电场分布，求解把缝效为传输线上对称T型网络时缝并联导纳与缝倾斜角度及切割深度的关系，同时，观察了波导壁厚度及缝宽对谐振频率的影响。计算数据与最新发表的实验数据比较，结果基本一致。     

耦合纵缝馈电的短路波导宽边纵缝阵的分析与设计

基于三层结构（馈电缝、耦合缝、辐射缝）平面缝隙阵天线设计的需要,用场分析法对由耦合纵缝馈电的两端短路波导宽边直线纵缝阵进行了分析和综合。该法考虑了所有的互耦、高次模及波导壁厚的影响,得到了耦合纵缝馈电的两端短路波民宽边纵缝直线阵在辐射缝偏心距相同和缝长相同时直线缝阵口径分布等幅同相的结论。利用所得结论并结合泰勒线阵综合法提出了适合于对文中系统进行综合的有效方法。     

Suspended Broadside-Coupled Slot Line with Overlay

This paper presents a rigorous analysis of symmetric, broad-side-coupled slot line with overlay. The structure is assumed to be suspended inside a conducting enclosure of arbitrary dimensions. The dielectric substrate and the overlay are assumed to be isotropic and homogeneous and are of arbitrary thickness and relative permittivity. The conducting enclosure and the zero thickness metallization on the substrate are assumed to have infinite conductivity. The computed results illustrate a) the dispersion characteristics and characteristic impedance of the coupled slot line structure, b) the variation of the even-mode and also the odd-mode relative wavelength ratio and characteristic impedance with slot width, and c) the effect of shielding on the even-mode and also the odd-mode dispersion and characteristic impedance. This structure should find application in the design and fabrication of MIC components such as magic-T's and directional couplers.     

Electromagnetic scattering from infinite periodic structures with alocalized impurity

An accurate hybrid technique for the analysis of electromagnetic scattering from an infinite periodic structure containing an impurity is presented in this paper. The hybrid formulation proposed combines a finite element method/Floquet modal expansion with the method of moments solution of a surface integral equation in the framework of an iterative approach. The impurity within the infinite periodic structure can be constituted by an arbitrary material with an arbitrary shape     

Suspended Slot Line Using Double Layer Dielectric

This paper presents a rigorous analysis of a) slot line on a double layer dielectric substrate, and b) slot line sandwiched between two dielectric substrates. The structure is assumed to be suspended inside a conducting enclosure of arbitrary dimensions. The dielectric substrates are assumed to be isotropic and homogeneous and are of arbitrary thickness and relative permittivity. The conducting enclosure and the zero thickness metallization on the substrate, are assumed to have infinite conductivity. The effect of shielding on the dispersion, characteristic impedance, and the effective dielectric constant are illustrated. These results should find application in the design and fabrication of MIC components and subsystems.     

Slot antenna impedance for plasma layers

The rectangular cavity or waveguide backed slot is covered by a plasma layer of finite thickness. The longitudinal variation of the voltage across the slot is obtained from the variational solution of an integral equation. The solution for plasma layer of finite thickness is obtained from the free space Green's function by the method of images. The fields outside the slot depend on the surface integral of the fields over the slot plane and over the surface of the plasma layer. If the thickness of the plasma layer is large compared with the wavelength, the fields on the surface of the plasma may be related to the voltage distribution along the slot by plane wave reflection coefficients. This leads to an integral equation that is reduced to a form suitable for machine computations. These calculations show the slot admittance to remain almost constant for plasma layers of various thicknessesh. The slot conductance tends to increase forh/ lambda <0.5. The presence of a plasma layer affects the voltage distribution along the slot for a center excited slot. The field distribution along the waveguide excited slot differs only slightly from the principal mode field distribution in the guide.     

Finite periodic structure approach to large scanning array problems

There are two conventional techniques dealing with mutual coupling problems for antenna arrays. The "element-by-element" method is useful for small to moderate size arrays. The "infinite periodic structure" method deals with one cell of infinite periodic structures, including all the mutual coupling effects. It cannot, however, include edge effects, current tapers, and nonuniform spacings. A new technique called the "finite periodic structure" method, is presented and applied to represent the active impedance of an array, it involves two operations. The first is to convert the discrete array problem into a series of continuous aperture problems by the use of Poisson's sum formula. The second is to use spatial Fourier transforms to represent the impedance in a form similar to the infinite periodic structure approach. The active impedance is then given by a convolution integral involving the infinite periodic structure solution and the Fourier transform of the equivalent aperture distribution of the current over the entire area of the array. The formulation is particularly useful for large finite arrays, and edge effects, current tapers, and nonuniform spacings can also be included in the general formulation. Although the general formulation is valid for both the free and forced modes of excitation, the forced excitation problem is discussed to illustrate the method.     

Equivalent Surface Impedance of an Infinite Periodic Array of Slot Impedance Loads with Dielectric Coating

The problem of plane-wave excitation of an infinite array of slot impedance loads with a dielectric layer is considered in order to determine the equivalent surface impedance. The solution of the problem is found by the method of integral equations, solved numerically by the Krylov–Bogolyubov method, which reduces the integral equation to a system of linear algebraic equations. The numerical results are presented in the form of dependences of the equivalent surface impedance on the geometric dimensions of the structure at fixed values of the period of the array, the angle of incidence, and the thickness of the dielectric layer. It is shown that the equivalent surface impedance can be controlled by varying the width of the slot and the strip conductor. The dependences obtained are compared with the characteristics of an array of slot impedance loads without a dielectric layer.     

Scattering of surface magnetostatic waves by periodic slot gratings

Scattering of the magnetostatic surface waves generated in thin films by the gratings formed from slots in a metal screen is theoretically analyzed. A boundary-value problem for the Maxwell equations is formulated and solved in the static approximation. An algorithm of numerical solution of the boundary-value problem is proposed. Scattering of magnetostatic surface waves by 2D periodic slot gratings that are infinite along one coordinate and finite along the other coordinate is studied for an arbitrary orientation of slots and an arbitrary angle of incidence of the magnetostatic wave. The band structure of gratings is studied. The possibility of formation of magnonic crystals based on slot gratings is demonstrated.     

Effects of ground plane dimensions on patterns radiated by slot antennas

Using a hybrid MoM-UTD formulation, this paper investigates the effects of ground-plane dimensions on the radiation fields of a slot antenna. It is shown that the radiated field strength of a slot cut in a finite ground plane is generally higher than that of a similar slot in a ground plane of infinite extent. Indeed, computational results reveal that the E-plane radiated field strength of a slot is about 3 dB higher when the ratio of the ground plane width to slot length is an even integer; and 1 dB higher when the ratio is an odd integer. In the case of the H-plane, the field strengths radiated by a slot in both infinite and finite sized ground planes are virtually identical, suggesting, therefore, that in this case, the contribution of the edge diffraction is insignificant. Results also indicate that a ground plane thickness of less than 20 mm has negligible effects on the radiation fields, as the strength of coupled fields, which is a manifestation of the effect of the finite thickness of the ground plane, is very small. As a validation, patterns computed compare favourably with experimental data available in the literature.     

Compound coupling slots for arbitrary excitation of waveguide-fedplanar slot arrays

A resonant coupling slot cut in the common broad wall of two crossed rectangular waveguides is analyzed. The slot is offset from the center line and tilted with respect to the longitudinal axis of the main waveguide, whereas it is centered-tiled in the branch waveguide. It is shown that the slot offset and tilt control the branch waveguide excitation amplitude with a phase variability of 360°. Pertinent integral equations are developed, taking into account finite wall thickness. The integral equations are solved for the slot aperture electric field using the method of moments. Dominant mode scattering by the slot in both waveguides is obtained     

Equivalent surface impedance of an infinite periodic array of slot impedance loads based on a semicylinder cavity

A problem of finding the equivalent surface impedance of an infinite periodic array of slot impedance loads based on a semicylinder cavity. The problem is solved by the integral-equation method. As the numerical method for solving the integral equation, the Krylov-Bogoliubov method is used. The results of the numerical experiment are presented in the form of dependences of the impedance on the cavity radius, slot width, conductor width, and angle of electromagnetic-wave incidence. The angular dependences of the impedance are compared to the earlier results obtained for an array of rectangular grooves and a single impedance load based on a semicylinder cavity.     

Wave penetration through bent slots

Shielding effectiveness of bent slots carved in a metal plate of finite thickness is analyzed by forming a set of integral equations based on the equivalence principle. Method of moments is used to solve the integral equations for the transmission cross sections. The effects of slot geometry, filling permittivity, and filling conductivity are studied. It is found that the penetrating field is mainly determined by the slot length, filling permittivity, and filling conductivity. Resonances are also observed when the slot length is integer multiples of half wavelengths     

Scan-independent slot arrays with parasitic wire arrays in astratified medium

The effect of a parasitic wire array on the scan admittance of a slot array has been investigated. Structures considered can consist of an infinite slot array and an arbitrary number of parasitic infinite arrays of piecewise linear wires, all arrays being embedded in a stratified medium. These include, as particular cases, phased arrays of Clavin elements. Expressing the fields from the arrays as plane waves, a procedure similar to the periodic moment method for infinite periodic structures is set up to obtain the scan admittance of the slot array. Scan admittances are presented for a slot array with monopole arrays in free space, and a slot array with a tilted dipole array in a stratified medium. Blind spots at which the incident energy is mainly reflected rather than transmitted were found. Results obtained indicate the possibility of using parasitic wire arrays for scan compensation of active slot arrays     

Equivalent surface impedance of an infinite array of slot impedance loads designed on the basis of coupled rectangular domains

A 2D design of an infinite array of slot impedance loads (SILs) is considered. Each SIL is designed from two coupled rectangular domains connected through apertures with both each other and free space. The integral equation method is used for determination of the equivalent surface impedance (ESI). Dependences of the ESI value are investigated for different geometric dimensions to wavelength ratios. It is shown that the SILs under study can be used to obtain a reactive component of ESI having either positive or negative sign for the thickness of the impedance structure not exceeding one-quarter the wavelength.     

Propagation characteristics of coplanar-type transmission lineswith lossy media

Lossy coplanar-type transmission lines are analyzed based on the hybrid-mode formulation by combining the spectral-domain approach with the perturbation method. Introducing a finite thickness of metallization and choosing the proper basis functions for the thick conductor model prevent the integrals used for calculating the conductor losses from becoming singular when evaluated at the conductor edge. An orthogonality relation is used to reduce the double infinite or semi-infinite integral to a single integral, thus reducing the computation effort drastically. Numerical computations by new basis functions for the thick conductor show convergence rates as fast as those for the zero-thickness cases. Numerical results include the effective dielectric constants, characteristic impedances, and total losses (conductor and dielectric losses) for slot lines and symmetrical and asymmetrical coplanar waveguides     

Analysis of planar arrays of shunt slots in ridged waveguides

Planar infinite arrays, comprising longitudinal slots cut in ridged waveguides, are analysed using a Galerkin formulation for the tangential electric field at both slot interfaces, combined with the finite element method for generating the waveguide Green function used in the integral equation. Computations agree very well with previously documented results