IEEE Transactions on Antennas and Propagation

A novel technique is presented to image stray signals in RCS measurement ranges. In this technique, the scattered fields of a flat plate in the diagonal plane are measured in a range for various frequencies and look angles. The scattered field data are then processed to generate an inverse synthetic aperture radar (ISAR) image of the diagonal flat plate. It is shown that scattering mechanisms asso... View full abstract»

An efficient physical optics based method of analysis of antennas over finite ground planes is presented. The far field radiated by the current on the finite ground plane is expressed as the convolution integral of the far field of the antenna above the infinite ground plane with the Fourier transform of the polygonal ground plane shape. The convolution integral is simplified by applying the sampl... View full abstract»

For transient excitation, it is well known that the ray optic solution is useful for early time descriptions but is not, in general, suitable for late time. On the other hand, the singularity expansion method (SEM) is a late time technique that is not in general suitable for early time. Perfectly conducting circular cylinder studies have shown that it is possible to obtain two hybrid formulations ... View full abstract»

Analytical bounds on the characteristics of beams generated by an arbitrary pulse-driven array are derived and supported with numerical calculations. These bounds extend the meaning of near-field distances or diffraction lengths to the situation where the array driving functions can be broad-bandwidth signals. Particular attention is given to transmitting and receiving array systems which consist ... View full abstract»

Inverse scattering for multiple conducting cylinders is investigated. It is assumed that a plane wave is incident upon separate perfectly conducting cylinders of unknown shapes and the scattered field is measured outside, then, using prior knowledge of the rough positions of the scatterers, the shapes of the conducting scatterers can be reconstructed. The Newton-Kanotrovitch method is employed to ... View full abstract»

An analysis of an electromagnetically coupled (EMC) dipole array is presented, in which a microstrip line is coupled to an infinite periodic linear array of microstrip dipoles, arranged perpendicular to the line. The spectral-domain immittance method is used to obtain the periodic Green's function for the two-layered structure, and the method of moments with a Galerkin testing procedure is then us... View full abstract»

Airborne or spaceborne radar systems often require tests before deployment to verify how well the system detects targets and suppresses clutter and jammer signals. The radar antenna diameter can be large and thus the conventional far-field test distance is impractical to implement. The theory and simulations of phase-focused near-field testing for adaptive phased array antennas is discussed. With ... View full abstract»

Rotationally symmetric arrays of circular waveguide fed apertures on conducting spherical surfaces have been analyzed. Representation of the outside electromagnetic fields in terms of spherical transmission line modes permits the array analysis to be viewed as a spherical waveguide junction discontinuity problem. The apertures, in general, carry dual polarized circular waveguide TE11 mo... View full abstract»

The recursive suppression algorithm is an adaptive algorithm that is one of the simplest superresolution algorithms to implement but, nevertheless, converges approximately as rapidly as the computationally intensive MUSIC algorithm. Simulation results verify the effectiveness of this algorithm in resolving closely spaced signals. Necessary and sufficient conditions for the convergence of the mean ... View full abstract»

A theoretical and numerical analysis of the annular-ring microstrip antenna with a dielectric cover is performed. The problem is formulated in the Hankel transform domain, taking a coaxial feed into consideration. The integral equations for the surface current density on the patch are derived. Galerkin's method is used to solve for the surface current density, and a stationary formula for the inpu... View full abstract»

The performance of adaptive arrays with arbitrary order derivative constraints to avoid the signal nulling caused by the error in the steering angle is investigated. The generalized sidelobe canceller (GSC) is used to evaluate the bearing responses of adaptive arrays with pointing errors. Under the assumption of equispaced linear arrays, the Legendre polynomial is used to derive a closed-form form... View full abstract»

Attenuation and phase shift of narrowband signals at radar and higher frequencies due to atmospheric layers of hydrometers are usually analyzed by solving the scattering amplitude of one particle numerically and then applying the necessary many-particle statistics. A case is made for an important simplification: use of an analytical solution for the one-particle scattering amplitude that is basica... View full abstract»

Two methods are presented to study the effect of a thin dielectric radome on the horizontal radiation pattern of TV transmitting antennas. Examples are given for two antenna systems, each consisting of four columns of horizontal dipoles supported by a perfectly conducting carrier post of either circular or square cross section. The radome is a thin circular cylindrical dielectric shell enclosing t... View full abstract»

Apparent computational difficulties with the direct integral equation and method of moments have prompted an alternative numerical solution procedure based on the spatial decomposition technique. Using rigorous electromagnetic equivalence, the spatial decomposition technique virtually divides an electrically large object into a multiplicity of subzones. It permits the maximum size of the method of... View full abstract»

Two methods of null steering in planar arrays are described. One is a direct application of linear-array techniques, and the other exploits the nonsymmetry of planar arrays to achieve localized nulls. As a result, null steering by the second method has little effect on the pattern shape and hence the antenna signal-to-thermal-noise ratio View full abstract»

A monolithic azimuthal monopulse antenna for 94-GHz applications has been developed. The structure consists of a single dipole suspended in one plane of an integrated horn cavity to obtain the sum pattern, and an antiparallel pair of dipoles suspended in a different plane of the same horn cavity to achieve the difference pattern. Pattern measurements of microwave models and on the millimeter-wave ... View full abstract»

A rigorous technique is presented for calculating the current induced on a thin lossy disk by rotationally symmetric sources, and the resulting scattered field. A Hallen-type integral equation is developed for the current using the magnetic vector potential, and it is solved by the method of moments. It is shown that the diffraction lobes usually associated with radiation above a finite circular g... View full abstract»

A modified electromagnetic beam technique is derived analytically from the asymptotic field expressions for the quasi-optical, millimeter-wave, plane polarized Laguerre-Gaussian modes of arbitrary order. The method makes use of the paraxial-wave formulas only, yet it accurately gives the full electric field vector at any point far beyond the conventional Gaussian beam regime. The technique is asse... View full abstract»

To obtain an accurate solution in the method of moments it is vital that an appropriate integral equation be used. In solving the problem of scattering from bodies of revolution with anisotropic surface impedance boundary conditions, different answers may result from seemingly minor differences in the integral equation formulations used. Different kinds of integral equations are compared with one ... View full abstract»