Analysis of finite parallel-plate waveguide arrays

The radiation and phase scanning properties of a planar array are investigated using wedge diffraction theory. The TEM and TE01radiation patterns are determined assuming that each guide is excited with equal amplitude but variable phase which is specified by the desired scan angle. Since the TE01pattern can be used directly as theH-plane radiation pattern of an equivalent rectangular waveguide array, the analysis for this instance is extended to consideration of aperture reflection coefficients     

Radiation from a parallel-plate waveguide with a finite corrugated flange

Wide-angle corrugated horns have found important practical application as feeds for reflector antennas, but as yet no satisfactory design theory exists. This letter presents results obtained using the method of moments for a 2-dimensional structure, whereby agreement between theory and experiment has been found to be excellent. This technique has the virtue that it can be readily applied to the more useful cylindrical geometry.     

Mutual coupling in finite coplanar rectangular waveguide arrays

Mutual admittance expressions are given for all possible combinations of mode coupling in an array of identical collinear rectangular waveguides opening into an infinite ground plane. Specific results are presented for the worst case of E-plane coupling between identical square waveguide to show that significant high-order mode excitation can occur. Some of these modes are a source of crosspolarisation, making mutual coupling important to the prediction of the crosspolar pattern of a rectangular waveguide array.     

矩形波导有限相控阵单元的阵中特性

利用矩时法对以矩形开口波辐射单元的有限相控的单元阵中方向图及口面磁流分布进行了计算。讨论了不同位置开口波导在不同扫描角时互耦对口面分布的影响。     

Analysis of interleaved arrays of waveguide elements

An analysis is presented of multiple interleaved arrays of waveguide radiators operating at different frequencies. The approach is a generalization of the analysis of an infinite array at a single frequency. The presence of the low-frequency elements affects the radiation characteristics of the high-frequency elements and generates grating lobes which do not appear in a single-frequency array. Furthermore, power is coupled 'into the low-frequency waveguides when the high-frequency elements are excited. Numerical examples are presented which show that these effects are not severe.     

TM-radiation from an obliquely flanged parallel-plate waveguide

Electromagnetic TM wave radiation from an obliquely flanged parallel-plate waveguide is studied. The Fourier-transform/series and Green's formula is used to represent the scattered wave and the simultaneous equations for the modal coefficients are formulated. Residue calculus is utilized to obtain a fast-convergent series solution. Numerical evaluation shows the behaviors of transmission, reflection, and radiation in terms of junction geometry and operating frequency.     

Monopole antenna radiation into a parallel-plate waveguide

A rigorous solution of coaxially fed monopole antenna radiation into a parallel-plate waveguide is obtained. The Fourier transform/series representations are used to represent scattered fields and the boundary conditions are enforced to obtain the simultaneous equations for discrete modal coefficients. Fast convergent series of the reflection coefficient is obtained and compared with other existing results     

Analysis of circular waveguide arrays on cylinders

An analysis is given of the mutual coupling effects in a finite array antenna of circular waveguide elements on a conducting cylinder. The array is described in terms of a scattering matrix and the multimode aperture fields of the elements are solved for by moment methods. Mutual coupling through wave propagation along the surface is treated according to GTD, since for most cases of interest the surface curvature is small in terms of wavelength. Appropriate asymptotic expansions for the magnetic field Green's function are derived for the two basic cases of an axial and a circumferential magnetic current element on the cylinder, the latter being a new case. The method, which allows the array elements to be nonuniformly spaced, applies to cylinders with radii>2lambdaand thus also includes planar arrays. Illustrative numerical examples and comparisons with infinite cylindrical and planar arrays are included.     

Surface crack detection using flanged parallel-plate waveguide

A flanged parallel-plate waveguide is used for the detection of a two-dimensional surface crack on a metal plate. The Fourier transform and the mode-matching technique are used to obtain simultaneous equations, which are solved to represent the crack characteristic signal. The characteristics of the crack, such as position, Width, depth, and material in the crack, are discussed in terms of the crack characteristic signal     

Radiation from dielectric-loaded arrays of parallel-plate waveguides

The problem of calculating the reflected and transmitted fields as a function of scan angle in an infinite phased array of parallel-plate waveguides is studied on an analytical basis. Two infinite sets of simultaneous linear equations are derived for the scattered fields internal and external to the waveguides. These sets of equations are attacked by a newly developed modified residue calculus method. Application of the results to the problem of designing rectangular waveguide arrays with improved impedance performance over a wide range ofH-plane scan angles is discussed. It is indicated that the present analysis may serve as a first step toward investigating the more general problem of phased arrays scanning at an arbitrary angle.     

Field distribution in a flanged parallel-plate waveguide

Field distributions in a flanged parallel-plate waveguide have been computed using the Weber-Schafheitlin integral technique. Equiamplitude and equiphase contours are presented in graphical forms for a specific choice of parameters.     

Radiation properties of an arbitrarily flanged parallel-plate waveguide

The radiation properties of an arbitrarily flanged parallel-plate waveguide are investigated by means of the boundary integral equations that are called guided-mode extracted integral equations. The boundary integral equations derived in this paper can be solved by the conventional boundary-element method. Numerical results are presented for a number of cases of flanged parallel-plate waveguide. Reflection coefficient, reflected and radiated powers as well as radiation patterns are numerically calculated for the incidence of transverse electric guided-mode wave.     

RCS of material partially loaded parallel-plate waveguide cavities

This paper analyzes electromagnetic scattering by a parallel-plate waveguide cavity whose internal region is partially loaded with materials and conducting plates. The radar cross section is investigated in terms of the loaded materials. The characteristics of cavity resonance are classified and thoroughly investigated. The numerical technique used is the point-matching method together with the edge condition for a conducting enclosure.     

A parallel-plate waveguide model of lossy microstrip lines

An improved semi-analytical model of a lossy microstrip transmission line is proposed. The model is based on the theory of the fundamental transverse magnetic mode of a lossy parallel-plate waveguide whose dielectric medium is assigned the effective permittivity of the respective lossless microstrip line. The complex propagation constant of the fundamental mode is computed by imposing the Leontovitch boundary condition at the upper and lower plates whose impedances take into account the thickness of the conductors and the current crowding effect. The dielectric loss is computed by perturbation formulas. The proposed model features high accuracy and computational efficiency at frequencies up to 100 GHz.     

Analysis of waveguide antenna arrays with protruding dielectricelements

The two-dimensional problem of radiation of TE and TM waves from a waveguide array with protruding smooth dielectric elements of arbitrary shape is considered, and solution algorithms are suggested. The algorithms are based on applying the method of auxiliary sources for the representation of electromagnetic fields outside and inside the protrusions in combination with the method of integral equations for the electric field at the waveguide aperture. The point matching of the field tangential components on the protrusion-to-free-space boundary and at the waveguide aperture is used to reduce the problem to a system of linear algebraic equations for the amplitudes of the auxiliary filamentary currents and of the waveguide aperture electric field, which is assumed to be piecewise constant. The amplitudes obtained from the solution of the system are used for computing the array reflection coefficient and element pattern, which are shown in some cases to be significantly dependent on the protrusion shape. Examples of arrays with flat-topped element patterns resulting from array geometry numerical optimization are also presented     

TE-scattering and reception by a parallel-plate waveguide array

TE-wave scattering and reception by a parallel plate waveguide array is Investigated. A Fourier-transform technique is used to express the scattered field in the spectral domain. The boundary conditions are enforced on the conducting surface and the array apertures to obtain simultaneous equations for the transmitted field inside the waveguide. The simultaneous equations are solved to obtain the transmitted field in a series representation whose first term is the Kirchoff solution. The behavior of the far-zone scattered field and the transmission coefficient are studied in terms of the scattering angle, array size, and frequency     

Analysis of a terminated parallel-plate waveguide with a slot in its upper plate

A slotted parallel-plate waveguide, terminated in a specified load, is analyzed in this paper. The guide is excited by an interior tem wave and illumination from an exterior source. An integral equation is developed for the unknown electric field in the slot and it is solved numerically for several cases of interest. Values of slot electric field, scattering parameters, and the far field radiated through the slot are presented graphically.     

手征负折射平行板波导中模式的新特性

从理论上研究了手征负折射平行板波导中的导模特性,给出了几个低阶导模的色散关系曲线和场分布、功率流分布.发现了一些新的特性:当手征参数较大发生负折射时基模缺失且色散曲线发生下凹;截止频率不再是传统定义中的纵向传播常数为零时所对应的频率,而是导模可以传播的最小频率;波导中存在后向波,总的功率流与波矢方向相反.     

Reflection coefficient of a parallel-plate waveguide illuminating a conducting sheet

The TEM mode reflection coefficient is analyzed for a symmetric parallel-plate waveguide composed of adjacent conducting wedges and radiating into a perfectly reflecting sheet oriented normal to the guide axis. Using the wedge diffraction method, the reflection from the conducting sheet is treated in terms of successive contributions or bounces that describe the interacting waves between the waveguide wedges and the reflecting sheet. For guides with small wedge angles (less than 75 degrees), the interacting waves can be treated as plane waves, and thus the reflection coefficient can be obtained through what is referred to as the self-consistent procedure. For guides with large wedge angles each of the interacting bounce waves can be resolved into component cylindrical waves. The total reflection from the sheet is then obtained by summing these iterative contributions. Calculated results from this analysis are in good agreement with measurements.     

Analysis of finite phased arrays of printed dipoles

The problem of a finite array of printed dipoles is treated, and results are presented in the form of reflection coefficient magnitudes, element patterns, and efficiency (based on power lost to surface waves). Various sized arrays are considered, and are compared with infinite array solutions. The excitation of surface waves is discussed in relation to the scan blindness phenomenon and the transition to an infinite array. Techniques for computational efficiency are also presented.