A perfectly matched layer (PML) absorbing material composed of a uniaxial anisotropic material is presented for the truncation of finite-difference time-domain (FDTD) lattices It is shown that the uniaxial PML material formulation is mathematically equivalent to the perfectly matched layer method published by Berenger (see J Computat Phys, Oct 1994) However, unlike Berenger's technique, the uniaxial PML absorbing medium presented in this paper is based on a Maxwellian formulation Numerical examples demonstrate that the FDTD implementation of the uniaxial PML medium is stable, equal in effectiveness as compared to Berenger's PML medium, while being more computationally efficient

An anisotropic perfectly matched layer-absorbing medium for the truncation of FDTD lattices

The spectrum of a commutative Banach ring Affinoid spaces Analytic spaces Analytic curves Analytic groups and buildings The homotopy type of certain analytic spaces Spectral theory Perturbation theory The dimension of a Banach algebra.

Spectral Theory and Analytic Geometry over Non-Archimedean Fields

The authors give a brief historic perspective of the coupled mode theory. The development and applications of the theory in microwaves in early years and in optoelectronics and fiber optics in recent years are described. They then consider lossless coupling of two modes in time. Two coupled resonance circuits, or two coupled microwave or optical resonators, are the physical examples. The start-up of a parametric oscillator is another example. Then they look at the formal derivation of coupled mode theory and consider the more general case when the modes are not energy-orthogonal and the energies are not necessarily positive. A more detailed account of the nonorthogonal coupled mode theory developed in the last five years for optical waveguides is given. >

Coupled-mode theory

In this paper, inkjet-printed UHF and microwave circuits fabricated on paper substrates are investigated for the first time as an approach that aims for a system-level solution for fast and ultra-low-cost mass production. First, the RF characteristics of the paper substrate are studied by using the microstrip ring resonator in order to characterize the relative permittivity (epsivr) and loss tangent (tan delta) of the substrate at the UHF band for the first time reported. A UHF RFID tag module is then developed with the inkjet-printing technology, proving this approach could function as an enabling technology for much simpler and faster fabrication on/in paper. Simulation and well-agreed measurement results, which show very good agreement, verify a good performance of the tag module. In addition, the possibility of multilayer RF structures on a paper substrate is explored, and a multilayer patch resonator bandpass filter demonstrates the feasibility of ultra-low-cost 3-D paper-on-paper RF/wireless structures.

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RFID Tag and RF Structures on a Paper Substrate Using Inkjet-Printing Technology

Liquid crystal polymer (LCP) is a material that has gained attention as a potential high-performance microwave substrate and packaging material. This investigation uses several methods to determine the electrical properties of LCP for millimeter-wave frequencies. Microstrip ring resonators and cavity resonators are measured in order to characterize the dielectric constant (/spl epsi//sub r/) and loss tangent (tan/spl delta/) of LCP above 30 GHz. The measured dielectric constant is shown to be steady near 3.16, and the loss tangent stays below 0.0049. In addition, various transmission lines are fabricated on different LCP substrate thicknesses and the loss characteristics are given in decibels per centimeter from 2 to 110 GHz. Peak transmission-line losses at 110 GHz vary between 0.88-2.55 dB/cm, depending on the line type and geometry. These results show, for the first time, that LCP has excellent dielectric properties for applications extending through millimeter-wave frequencies.

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Characterization of liquid crystal polymer (LCP) material and transmission lines on LCP substrates from 30 to 110 GHz

A direct three-dimensional finite-difference time-domain (FDTD) method is applied to the full-wave analysis of various microstrip structures. The method is shown to be an efficient tool for modeling complicated microstrip circuit components and microstrip antennas. From the time-domain results the input impedance of a line-fed rectangular patch antenna and the frequency-dependent scattering parameters of a low-pass filter and a branch-line coupler are calculated. These circuits were fabricated and the measurements made on them are compared with the FDTD results and shown to be in good agreement. >

Application of the three-dimensional finite-difference time-domain method to the analysis of planar microstrip circuits

A sector-shaped configuration for designing planar power divider-combiner circuits that are compatible with microstrip circuits is discussed. This configuration is analyzed using the two-dimensional planar circuit approach. Expressions for impedance matrix parameters of multiport sectorial planar circuits are given. Theoretical and experimental results reported for 90 degrees and 180 degrees power dividers are in good agreement. >

Multiport power divider-combiner circuits using circular-sector-shaped planar components

Analysis and design of planar microwave components

A generalized method for evaluating the scattering parameters of a multiport center-fed circular microstrip disk power divider/combiner circuits is presented. The method is based on the planar circuit approach in which the two-dimensional Green's function of a circular segment is used. Various symmetrical power divider/combiner circuits have been designed and tested. The effect of introducing additional shorted ports between the circumferential output ports on the reduction of spurious radiation losses is discussed. Experimental results verifying the design methodology are given.

Multiple-Port Power Divider/Combiner Circuits Using Circular Microstrip Disk Configurations

A generalized method for evaluating the S-parameters of a multiport circular microstrip disc circuit is presented. The method is based on the planar circuit approach in which the two-dimensional Green's function of a circular segment is used. Three different applications of multiport circular disc structures are illustrated by designing, i) a broadband (44 percent bandwidth for |S/sub 11/| < 0.2) five-port network suitable for six-port network analyzers, ii) a broad-band three-way power divider with -3 dB, -6 dB, and -6 dB outputs, and iii) a four-port microstrip "cross-over." Experimental results verify the design methodology in all of these three cases.

M.D. Abouzahra

Papers

Application of the three-dimensional finite-difference time-domain method to the analysis of planar microstrip circuits

Multiport power divider-combiner circuits using circular-sector-shaped planar components

Analysis and design of planar microwave components

Multiple-Port Power Divider/Combiner Circuits Using Circular Microstrip Disk Configurations

Analysis and Design of Four-Port and Five-Port Microstrip Disc Circuits