Jerzy Mazur

On the mode coupling in longitudinally magnetized waveguiding structures

Propagation in waveguiding structures containing gyromagnetic material with longitudinal magnetization is analyzed in terms of the coupling between modes having different symmetry properties. It is found that the wave supported by a symmetrical structure of two coupled guides is a combination of the even and odd modes propagating in an isotropic structure. The gyromagnetic medium causes the coupling between the modes, and the energy of the wave is periodically transferred from one mode to another, which in turn results in the exchange of energy between guides. The proposed mathematical model explains the operation of novel nonreciprocal devices. >

Nonreciprocal operation of structures comprising a section of coupled ferrite lines with longitudinal magnetization

Nonreciprocal devices based on a section of two coupled lines containing ferrite magnetized in the propagation direction are investigated. The necessary conditions for nonreciprocal operation are derived. Several configurations are proposed and their scattering matrices are given. An explanation of the action of experimental devices constructed by other researchers is proposed and substantiated by a numerical investigation of their simplified models under nonideal operating conditions. >

Rigorous modal analysis of structures containing inhomogeneous dielectric cylinders

The orthogonal expansion method and modified iterative scattering procedure is proposed to analyze structures containing asymmetrically located, partial-height, or multilayered inhomogeneous dielectric posts. The analysis is based on a novel concept called the hybrid impedance matrix (HIM), which describes the relation between the total scattered electric and magnetic fields obtained from all posts. As a result, the HIM can be easily applied to match it with other known incident fields and finds applications in closed (waveguide junctions, resonators) and open structures (posts in free space for plane-wave excitation). Additionally, a procedure for constructing eigenmode functions describing field components in the inhomogeneous dielectric cylinders is presented. The proposed method has been extensively verified for a rectangular waveguide junction by a finite-difference time-domain software package, as well as our own measurements and, in both cases, very good agreement can be observed.

Coupled-mode design of ferrite-loaded coupled-microstrip-lines section

A coupled-mode approach is applied to a microstrip circulator with a distributed section of axially magnetized ferrite coupled lines (FCLs). The equivalent model of the FCL junction is found, which includes gyromagnetic interaction between propagated and evanescent isotropic modes. On the basis of the coupling process, the ferrite modes in the FCL are defined. From the decomposition of these modes, the waves in each line of the structure are determined. The mode matching is applied at the junction ports, which allows one to obtain the scattering matrix of the microstrip FCL. Validity of the approach is verified by checking the scattering parameters of the FCL section and comparing the numerical results with available measurements. The proposed model gives the properties with regards to the impedance matching and ferrite section dimensions, which can help the design of the FCL nonreciprocal devices. As an example, the S-parameters of an FCL circulator are presented.

Simulation and Experiment of a Compact Wideband 90

A compact wideband 90° differential phase shifter is developed by modifying ports termination in the Abbosh phase-shifter configuration. This novel phase-shifter arrangement consists of a 3-dB directional coupler with the coupled and transmission ports terminated with reactive loads. The proper reactance is found at the input of the coupled line section in which the remaining ports are open circuited. Both coupled sections utilize a multilayer broadside coupling microstrip-slot-microstrip tight coupler. A theoretical model is presented to explain the performance of the proposed phase shifter and design procedure. Further, the phase shifter was designed and manufactured. Results of calculation and measurement show that the developed circuit provides a 90° differential phase shift with deviation less than ±4° across the 3-7-GHz frequency band.

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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.

Differential Phase Shifter

Complex waves in shielded lossless inhomogeneous isotropic guides are investigated. A critical appraisal of the existing theory of complex waves is given and a new approach is proposed. A mathematical condition for the existence of complex waves is derived using the properties of a generalized symmetric matrix eigenvalue problem. It is shown that complex waves may exist in slightly perturbed homogeneous guides as a result of the coupling of a pair of degenerate or nearly degenerate modes. >

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

The design and experimental results for a novel three-port finline circulator are presented for the frequency range 26-40 GHz. The circulator consists of a T/sup E/-junction cascaded with the section of ferrite coupled slot finlines magnetized in the propagation direction. The T/sup E/-junction structure refers to a transition from a unilateral single slot finline taper to a coplanar line region via a tapered center conductor. The design procedure for the structure is described and confirmed by experimental results. The proposed structure belongs to the family of the distributed coupled ferrite line nonreciprocal devices suitable for application in the millimeter-wave range. >

Matrix theory approach to complex waves (in shielded lossless guides)

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.

Millimeter-wave three-port finline circulator using distributed coupling effect

The paper presents the design of a compact ultra wideband antenna composed of two circular coplanar strips which enclose slot aperture of the similar shape. The antenna is fed with three coplanar strip-lines of 50 Ω. The effect of the outer strip edge on the antenna bandwidth is investigated. This antenna configuration has been modeled and experimentally tested, showing good performance in 1.7–15.5 GHz frequency range where return losses |S 11| < –10 dB are achieved. Stable radiation patterns across the whole band is also observed.