Adam Kusiek

Analysis of Scattering from Arbitrary Configuration of Cylindrical Objects Using Hybrid Finite-Difference Mode-Matching Method

This paper presents a new hybrid flnite-difierence frequency domain | mode-matching method (FDFD-MM) for the analysis of electromagnetic wave scattering from conflguration of metallic or dielectric cylindrical posts with arbitrary cross-section. In our approach each scatterer is treated as an efiective circular cylinder represented by impedance matrix deflned in its local coordinate system. In order to obtain the scattering parameters of arbitrary conflguration of objects in global coordinate system an analytical iterative scattering procedure (ISP) is applied. This work is an extension of our previously published results, where our consideration were limited to two dimensional (2D) problems with TM excitation. In this paper, we extended our analysis to two-and-a-half dimensional (2.5D) problems. The accuracy of the proposed method is presented and discussed. To verify our approach some numerical examples are presented. The obtained results are compared with the results published in literature and the ones obtained from own measurements and commercial software.

A New Hybrid Method for Analysis of Scattering From Arbitrary Configuration of Cylindrical Objects

A new hybrid method for analysis of scattering on configuration of cylindrical objects with arbitrary geometries is presented. In this approach each scatterer is treated as an effective circular cylinder represented by its impedance matrix. To obtain the impedance matrix representation of the arbitrary geometry post the combination of finite-difference frequency-domain (FDFD) and mode matching (MM) technique is applied. In the analysis of an arbitrary configuration of objects the iterative scattering procedure (ISP) is used. The error estimation of the method and numerical results are presented and discussed. A good agreement of the presented results with analytical approach and commercial finite-difference time-domain (FDTD) software is obtained.

An Analysis of Probe-Fed Rectangular Patch Antennas With Multilayer and Multipatch Configurations on Cylindrical Surfaces

A multipatch configuration of probe-fed rectangular microstrip antennas mounted on a cylindrical body, with electrically small radius, with an arbitrary number of substrate and superstrate layers is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. A unified procedure for creating proper matrices for the investigated geometry of the structure is outlined here. Numerical results for the input impedances and radiation patterns are calculated and verified by comparing them with results from the literature and our own measurements of manufactured prototypes.

HYBRID TECHNIQUE FOR THE ANALYSIS OF SCATTERING FROM PERIODIC STRUCTURES COMPOSED OF IRREGULAR OBJECTS

In the paper, the analysis of electromagnetic wave scattering from multilayered frequency selective surfaces is presented. The surface is composed of periodically arranged posts with irregular shapes. The multimodal scattering matrix of such structure is derived and the transmission and re∞ection characteristic for the structure with arbitrary plane wave illumination are calculated. The exact full- wave theory based on the hybrid approach employing mode-matching method and flnite-difierence frequency-domain (FDFD) technique is applied to develop an e-cient theory to analyze such structures. The validity and accuracy of the approach are verifled by comparing the results with those obtained from alternative methods and own measurements of manufactured periodic structures.

An Analysis of Elliptical-Rectangular Multipatch Structure on Dielectric-Coated Confocal and Nonconfocal Elliptic Cylinders

A rigorous analysis of the resonance frequency problem of an elliptical-rectangular microstrip structure mounted on dielectric-coated elliptic conducting cylinder, with electrically small radius, is investigated in this paper. A full-wave analysis and a moment-method calculation are employed. The analysis is carried out considering the expansion of the field as a series of Mathieu functions. The complex resonance frequencies of the structure are studied. Modes suitable for antenna application are also investigated. Numerical results for the complex resonance frequency and radiation patterns are calculated and verified by comparing them with results from commercial software and our own measurements of manufactured prototypes. The difference between confocal and nonconfocal dielectric-coated elliptic cylinders is investigated.

Investigations of Cylindrical Ferrite Coupled Line Junction Using Hybrid Technique

In this paper, a novel longitudinally magnetized cylindrical ferrite coupled line (CFCL) junction is proposed. In comparison to planar ferrite coupled line (FCL) conflgurations, which are well known in literature, in such structure the higher gyromagnetic coupling occurs. This allows to obtain the required in FCL devices Faraday rotation angle …=4 for the ferrite with shorter length and lower value of magnetization. As a result the total insertion losses in the ferrite section can be reduced using the proposed topology. In the analysis of the proposed CFCL junction a hybrid technique combining method of moments and coupled mode method (MoM/CMM) is applied. The results are compared with the ones obtained from commercial software HFSS and a good agreement is obtained.

Microstrip Ferrite Coupled Line Isolators

The double isolators using sections of ferrite coupled microstrip lines are demonstrated in a layered and planar approaches. The configurations are investigated both theoretically and experimentally at the frequency range 8-15 GHz. The better performances are observed for planar configuration that reports reflection losses -15 dB, isolation better than -18 dB and average insertion losses about 3 dB.

Investigations of four-port circulator utilizing cylindrical ferrite coupled line junction

In this paper the numerical and experimental investiga- tions of four-port circulator utilizing longitudinally magnetized cylin- drical ferrite coupled lines (CFCL) section are presented for the flrst time. In comparison to earlier models the proposed structure of cir- culator utilizes multilayer magic-T junction cascaded with cylindri- cal ferrite section of …=4 Faraday angle. The advantage of utilization of cylindrical section over the planar one is the possibility to design shorter ferrite junctions ensuring lower insertion losses. Moreover, the multilayer magic T-junction allows to improve performance of the pro- posed circulator by omitting the bandwidth limitation which exists in commonly used hybrid couplers with air-bridges. In the analysis of CFCL junction the full wave hybrid approach combining flnite difier- ence frequency domain method with method of moments and mode matching technique is applied. The planar feeding structures of circu- lator are designed with the use of commercial software. The simulated results of the entire circulator are compared with the measurement results of the fabricated prototype and a good agreement is achieved.

Investigations of nonreciprocal devices employing cylindrical ferrite coupled line junction

This paper presents application of a novel cylindrical ferrite coupled line (CFCL) junction to integrated nonreciprocal devices. In such a junction, high gyromagnetic coupling occurs. This gives possibility to design a Faraday rotation CFCL junction with the ferrite rod having shorter length and lower saturation magnetization than the planar structures commonly known in literature. By utilizing the proposed cylindrical junction in integrated nonreciprocal devices, it is possible to reduce not only their dimensions but also the insertion losses occurring in such structures. In this paper, we present an application of CFCL junction to integrated isolator. The results of numerical simulations are verified experimentally, and good agreement is observed.

Hybrid Finite-Difference/Mode-Matching Method for Analysis of Scattering from Arbitrary Configuration of Rotationally-Symmetrical Posts

In this paper, the hybrid approach to the analysis of electromagnetic wave scattering from arbitrary conflguration of body- of-revolution (BOR) posts is presented. The proposed approach is based on the representation of each scatterer or set of scatterers by an efiective sphere with the known boundary conditions deflned by transmission matrix. In the analysis of each single axially- symmetrical post with irregular shape we utilize the flnite-difierence frequency-domain/mode-matching technique (FDFD/MM). Then the scattering parameters of investigated set of posts are obtained utilizing the analytical iterative scattering procedure (ISP). This work is an extension of our previously published results where the proposed technique was deflned in cylindrical coordinates and was limited to conflgurations of inflnitely long parallel cylinders with arbitrary cross- section. In this paper we extend this method by formulating it in spherical coordinates. This allows us to signiflcantly increase the versatility of the developed approach and in result to include in the analysis the sets of arbitrary located and oriented rotationally- symmetrical posts. The accuracy and e-ciency of the proposed technique are discussed. The presented numerical results are verifled with the ones obtained from commercial software.