摘要:

Nonreciprocal wave propagation is studied in a hollow image guide containing a ferrite layer. The analysis is conducted by means of the effective-dielectric-constant method. Numerical results are compared with experimental results in the Ka band, and the possibility of using the structure as a millimetre-wave isolator is discussed.

DOI:10.1049/ip-h-2.1985.0041

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Based on the well-known microstrip-slot coupler an interesting nonreciprocal extention is proposed. It is shown that a 4-port circulator can be obtained if an additional ferrite substrate is underlayed on the slot side. TheS-parameters of this new device are derived, and the electrical properties are discussed. First experiments verify the correctness of the theory.

DOI:10.1049/ip-h-2.1985.0042

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Wave-propagation equations of nonreciprocal cylindrical helix phase shifters are conventionally solved using mathematical functions, for which extensive tables are not easily available. The finite-element method (FEM) appears to be a comparatively easier means of solving these problems. The paper describes the application of the finite-element method to a very complex problem: a gyromagnetic medium with periodically varying spatial boundary conditions. The results of finite-element analysis of a normal, an inverted and a ferrite-embedded helix ferrite phase shifter in circular cylindrical geometry are presented. The relative effectiveness of these three phase shifters is studied to show that the differential phase shift is large in the case of the normal helix compared with the inverted helix.

DOI:10.1049/ip-h-2.1985.0043

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Ferrite devices based on Faraday rotation remain of interest at both microwave and millimeter wavelengths. Although a complete mathematical description of ferrite cylinders in round waveguides is available, the experimental verification of rotation or differential phase shift in a round waveguide is not simple. The paper describes a resonant cavity procedure which permits the evaluation of the two propagation constants in such a magnetised waveguide. It is obtained by incorporating the Faraday rotator section into a resonator structure by closing both ends of the waveguide and separately tuning its length for each of the two split branches of the magnetised resonator to the frequency of the demagnetised one. The paper includes a lower bound on the length of the rotator bit (or an upper bound on the splitting between the phase constants) in terms of the directivity of the section.

DOI:10.1049/ip-h-2.1985.0044

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A field displacement isolator design in finline technique is described using a lamella structure including a ferrite layer, energy absorbing layers and a dielectric spacer layer. An isolator with a forward insertion loss of 1.3 dB and a reverse loss higher than 35 dB at 28.5 GHz was developed. The design was based on a field theory for the calculation of the power-density distribution inside the isolator, exact measured material parameters of the ferrite material and experimental optimisation of the lamella structure. The design procedure and the results are described in detail.

DOI:10.1049/ip-h-2.1985.0045

出版商:IEE    

年代:1985

数据来源: IET

摘要:

High-power tunable microwave filters can be made with ferrimagnetic materials by using coupled spin wave, electromagnetic wave modes of propagation which are decoupled from the processes that limit the power handling capability of conventional YIG filters. These novel filters can be used for spectral containment of transmitter emissions, or as feedback elements with microwave amplifiers, so as to create high-power tunable oscillators. Measurements have been made at X- and S-bands on one implementation of this technique, namely a pair of waveguides coupled via a polycrystalline YIG disc. Linear operation to 20 kW has been achieved.

DOI:10.1049/ip-h-2.1985.0046

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The contour-integral formulation has been demonstrated to be well suited for the description of planar junction circulators. It is employed in the paper to investigate the complex-gyrator admittance of planar circulators using side-coupled triangular resonators. As the field of solutions exhibited by this resonator is as rich and varied as that employing the classic disc, one computer-orientated practice is essential for everyday design. Circulation solutions using wide coupling angles are more readily realised using this resonator shape, without destroying its character, than is the case with other configurations.

DOI:10.1049/ip-h-2.1985.0047

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The nonreciprocal propagation of rotationally symmetric TE-modes along a circular guide, uniformly filled with latching ferrite magnetised azimuthally to remanence, is studied theoretically. The boundary-value problem is solved in terms of Kummer confluent hypergeometric functions of complex parameter and variable. An asymptotic method for solution of the characteristic equation is developed, providing a basis for numerical computation of the eigenvalue spectrum and phase characteristics of the structure with a fair degree of engineering accuracy. The normalised nonreciprocal phase characteristics and the differential phase shift of the waveguide under rotationally symmetric TE-mode excitation are presented for both latched states of ferrite remanent magnetisation. The potentialities of the structure as digital nonreciprocal phase shifter and/or bistable ferrite switch using intrinsic advantages of ferrite remanent magnetisation are discussed.

DOI:10.1049/ip-h-2.1985.0048

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The paper outlines the construction and operation of a simple hot-pressing system that has been used to produce small volumes of yttrium iron garnet. The products have high density, a limited grain-size distribution and compare favourably with conventionally fired material. Simple changes in pressing conditions enable the sample porosity to be varied in a controlled manner, and results are presented indicating the way in which the most important loss parameter of the material for device applications, the effective linewidth ΔHeff, changes with these variations.

DOI:10.1049/ip-h-2.1985.0049

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Preliminary experimental results are presented on novel nonreciprocal coupling between two identical dielectric image lines. This is produced by loading the coupling region with a longitudinally magnetised ferrite. Measurements in the frequency range 26.5–40 GHz show a differential insertion loss of greater than 15 dB, over a bandwidth of approximately 1.5 GHz between 30 GHz and 35 GHz, produced by reversing the bias field. The minimum insertion loss was approximately 5 dB over this bandwidth, and the return loss was better than 13 dB. These results can be improved and this effect can be used to develop four-port circulators for millimetric wavelengths.

DOI:10.1049/ip-h-2.1985.0050

出版商:IEE    

年代:1985

数据来源: IET