https://web.stanford.edu/group/fan/publication/Liu_ComputerPhysicsCommunications_183_2233_2012.pdf

S4 : A free electromagnetic solver for layered periodic structures

A parameter study of Vivaldi notch-antenna arrays demonstrates that the wide-band performance of these antennas can be improved systematically. Stripline-fed Vivaldi antennas are comprised of: (1) a stripline-to-slotline transition; (2) a stripline stub and a slotline cavity; and (3) a tapered slot. The impedances of the slotline cavity and the tapered slot radiator combine at the transition to yield an equivalent series impedance on the feedline. The stripline stub can be represented by a series reactance. The resistance and reactance of the antenna impedance yield insights into the effects of various design parameters. In particular, it is found that the minimum operating frequency can be lowered primarily by increasing the antenna resistance through a change of design parameters. However, beyond a limit for each design parameter, the in-band performance begins to deteriorate. Plots of antenna impedance versus frequency for several parameter variations have been obtained by using a full wave method of moments analysis of infinite arrays. These plots provide a means for designers to systematically improve array performance with bandwidths in excess of 6:1 having been achieved.

A parameter study of stripline-fed Vivaldi notch-antenna arrays

Aspects of the subject disclosure may include, for example, receiving, by a feed point of a dielectric antenna, electromagnetic waves from a dielectric core coupled to the feed point without an electrical return path, where at least a portion of the dielectric antenna comprises a conductive surface, directing, by the feed point, the electromagnetic waves to a proximal portion of the dielectric antenna, and radiating, via an aperture of the dielectric antenna, a wireless signal responsive to the electromagnetic waves being received at the aperture. Other embodiments are disclosed.

Method and apparatus for coupling an antenna to a device

A distributed antenna system is provided that frequency shifts the output of one or more microcells to a 60 GHz or higher frequency range for transmission to a set of distributed antennas. The cellular band outputs of these microcell base station devices are used to modulate a 60 GHz (or higher) carrier wave, yielding a group of subcarriers on the 60 GHz carrier wave. This group will then be transmitted in the air via analog microwave RF unit, after which it can be repeated or radiated to the surrounding area. The repeaters amplify the signal and resend it on the air again toward the next repeater. In places where a microcell is required, the 60 GHz signal is shifted in frequency back to its original frequency (e.g., the 1.9 GHz cellular band) and radiated locally to nearby mobile devices.

Remote distributed antenna system

Aspects of the subject disclosure may include, for example, a device that facilitates transmitting electromagnetic waves along a surface of a wire that facilitates delivery of electric energy to devices, and sensing a condition that is adverse to the electromagnetic waves propagating along the surface of the wire. Other embodiments are disclosed.

Method and apparatus for sensing a condition in a transmission medium of electromagnetic waves

An array of antenna feed elements includes a plurality of horns, each horn having an aperture and configured for transmission of electromagnetic energy therethrough. At least a first horn is configured with an electrically conductive external surface proximate to the aperture, the external surface contoured so as to reduce mutual coupling between the first horn and an adjacent horn. Where the electromagnetic energy is within a radio frequency (RF) band, the external surface is contoured so as to provide an abrupt change in a gap dimension between the first horn and an adjacent horn, the change occurring at a distance behind the aperture of equal to a multiple of one half the characteristic wavelength of the RF band.

Antenna array with reduced mutual coupling between array elements

Rotman lenses are attractive candidates for use in beam forming networks (BFNs) for satellitebased direct radiating arrays. This paper will review the basic design equations for a Rotman lens and will describe Rotman lens synthesis and analysis software developed by the author. The synthesis tool, named RLDESIGN, is written in MATLAB to automatically and rapidly solve the Rotman lens equations and interactively display the resulting lens geometry and performance parameters. It features a full graphical user interface customized to easily design, tune, and optimize a Rotman lens for a given application. The more rigorous analysis tool, named NARL (Numerical Analysis of Rotman Lens), is written in MATLAB and Fortran 95 and is based on a boundary integral/surface integral hybrid formulation. NARL uses a unique wide-band expansion of the parallel plate Green’s function to enable rapid analysis of the lens for a large number of frequencies. To demonstrate the accuracy of the codes, comparisons are presented of the predictions of both RLDESIGN and NARL to measurements on a prototype Rotman lens.

Analysis and synthesis of rotman lenses

New formulas for the two-dimensional Fourier transform of functions with polygonal support and linear amplitude variation are derived from the corresponding formula for a constant function. These expressions, valid for all nonzero values of the transform variable k, are superior to those previously reported, which fail when k is perpendicular or parallel to any edge of the polygon. These transforms have applications in diffraction theory and computational electromagnetics. >

The Fourier transform of linearly varying functions with polygonal support

Previously published methods for pyramidal horn gain calculation have used an approximate expression for the path length error that gives rise to aperture quadratic phase error. In this study pyramidal horn gain is calculated without approximating the path length error. These improved accuracy gain calculations give results equal to the previous approximate calculations for large apertures (A or B>50 lambda ) or small peak aperture phase error in wavelengths (S or T 0.6) the improved accuracy method can yield lower gain than the previous calculations, especially for an E-plane flare. >

Pyramidal horn gain calculation with improved accuracy

An efficient formulation is described for calculating all vector and scalar potential Green's functions for a thin, infinitely long waveguide with periodic excitation. The Green's functions are represented by the first few terms of the modal expansion plus a quasi-static correction. This allows one to compute the Green's functions over a wide band of frequencies with little additional effort over that required for a single frequency. An attractive feature of the method is that the l/R free-space singularity exhibited by the potentials is explicitly extracted in the lowest order quasi-static term. Tfris is convenient for evaluating method-of-moments self-term contributions in closed form. The Green's functions have application for problems involving stripline structures such as Rotman lenses.

An Efficient Technique for Computing the Potential Green's Functions for a Thin, Periodically Excited Parallel-Plate Waveguide Bounded by Electric and Magnetic Walls

P.S. Simon

Papers

Antenna array with reduced mutual coupling between array elements

Analysis and synthesis of rotman lenses

The Fourier transform of linearly varying functions with polygonal support

Pyramidal horn gain calculation with improved accuracy

An Efficient Technique for Computing the Potential Green's Functions for a Thin, Periodically Excited Parallel-Plate Waveguide Bounded by Electric and Magnetic Walls