Artificial Neural Network Models for Coaxial to Waveguide Adapters

Artificial neural networks provide fast and accurate models for the modeling, simulation, and optimization of microwave and millimeter wave components. In this paper, a multilayer perceptron neural network (MLPNN) is used to model a millimeter wave coaxial to waveguide adapter. The MLPNN is electromagnetically developed with a set of training data that are produced by the full-wave finite-difference time-domain (FDTD) method. One type of the designs of experiments, the central composite technique, is used to allow for a minimum number of FDTD simulations that is needed to be performed. The MLPNN models are useful for the CAD of wideband coaxial to waveguide adapter.     

A Compact Monopulse Radial Line Slot Array Antenna at Millimeter Wavelengths

This paper describes the design and performance of a radial line slot array antenna (RLSA) which generates sum or difference far field patterns. The antenna consists of rectangular waveguide to radial line transition, radial line and slot arrays etched on the upper plate of the radial line. A novel rectangular waveguide to radial line transition is designed to build up the dominate TEM mode in radial line to excite the slot arrays which are arranged in concentric rings on the upper plate of the radial line. The antenna radiates linear polarization at Ka band. Monopulse operation is obtained by a sum and difference network which is a compact eight-port comparator consisting of coplanar magic tees. The sum and difference network is waveguide structure whose loss is less than that of microstrip structure at millimeter wave lengths. The monopulse performances can be used in monopulse tracking and anti-collision application etc. Genetic algorithm (GA) is applied to optimize the parameters of the transition and antenna to obtain good performances. Note: Part of this paper has been presented in the oral session ThuA5 on Transmission Lines and Antennas in IRMMW-THz2006 Conference, pages: 535.Number: 376636Title: Radial line slot array antenna at millimeter wave lengths     

Full-Wave Analyses of Coaxial to Waveguide Adapters by the FDTD Method

The finite-difference time-domain (FDTD) method is applied to the full-wave analyses of the electrical properties of millimeter wave coaxial to waveguide adapters. The results are useful for the design of wideband coaxial to waveguide adapter.     

Analysis of the H-Plane T-Junction Millimeter Wave Waveguide Circulator with a Ferrite Sphere

This paper presents an approximate but efficient field treatment of the new easy-to-fabricate ferrite sphere based H-plane waveguide circulator for potentially low-cost millimeter wave communication systems. A new three-dimension modeling strategy using a self-inconsistent mixed coordinates based mode matching technique is developed, i.e. the solutions of the Helmholz wave equations in the ferrite sphere and in the surrounding areas are deduced in the form of infinite summation of spherical, cylindrical and general Cartesian modes respectively. The point matching method is then used on the interface to numerically obtain the coefficients of different orders basis functions of the field. Therefore, the field distributions as well as the characteristics of the circulator are numerically calculated and the good agreement is observed between the numerical results and the measured data.     

Calculation of external circuit impedances of mm-wave oscillator cavities by a rigorous field analysis method

This paper presents a generalized field analysis method for calculating the external circuit impedances looking outside from the active devices of some millimeter wave oscillators. For a simple oscillator model with a radial disc and a diode existing in a rectangular waveguide, the numerical results are in agreement with the experimental data. Impedance characteristics for several different oscillator configurations are given, and some useful conclusions for oscillator design are derived.     

Fast Stimulation of Millimeter Wave Waveguide Filters by Boundary Marching Method

The boundary marching method is applied for the analysis of the waveguide bandpass filers. The vector finite element method with the perfectly matched layers (PML) as the matching load is given for parameter extraction of millimeter wave filters. The implementation of the fast boundary marching method is described in detail. The reflection and insertion losses of millimeter wave filters are obtained and compared with those obtained from literature.     

Mode matching analysis of the dielectric waveguide 3-D discontinuity problem

In this paper, the dielectric waveguide 3-D discontinuity problem is investigated by the method which combines the multimode network theory with the rigorous mode matching procedure both in the transverse cross section and in the longitudinal direction. Good agreement has been found between the numerical results and the experimental data in the literature, and the effectiveness and accuracy of the present method are justified. Some numerical results are given to establish useful guidelines for the design of dielectric waveguide components in the millimeter and optical wave integrated circuits.     

Method for radar cross section measurements in millimeter and submillimeter wave regions

We present a new method for electromagnetic modeling radar scattering processes. In this method we use a quasi-optical waveguide of the type of "hollow dielectric waveguide" as a fundamental component of radar cross section (RCS) instrumentation systems. Such waveguide structure produces required target-illuminating quasiplane wave and suppresses unwanted waves as well as transmits the legitimate signal from test object, mounted inside this waveguide, to the reception zone. Presented method is especially effective one in millimeter and submillimeter wave regions, in particular, for investigation RCS of targets with small reflectivity.     

Artificial Neural Network Model for the Gap Discontinuity in Shielded Coplanar Waveguide

Fast and accurate component models are essential for the development of three dimensional millimeter wave integrated circuits. In this paper, an accurate and efficient artificial neural network (ANN) model for the gap discontinuity in shielded coplanar waveguide is presented. The ANN model is developed with a set of training data given by the finite-difference time-domain simulation and can be used in the frequency scope of 0100GHz.     

Analysis of the characteristics of NRD waveguides loaded with periodic metallic strips by using the method of lines for millimeter wave filter and antenna application

In this paper, the propagation characteristics of NRD waveguide loaded with periodic metallic strips are analyzed in terms of the method of lines. Numerical results show that such structures are most suitable for millimeter wave bandstop filter and NRD waveguide beam scanning leaky wave antenna application.