摘要:

A finline resonance isolator is an attractive solution to the construction of millimetre wave isolators, except for the fact that a large direct magnetic field is normally required for its operation. One way to overcome this drawback is to employ an hexagonal ferrite material with a large internal uniaxial anisotropy energy. Such devices are simple to fabricate and provide perhaps the most practical solution to the design of millimetre band isolators. The paper describes some experimental finline devices in WR 42 waveguide.

DOI:10.1049/ip-h-2.1985.0015

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A millimetre wave six-port reflectometer for the measurement of complex voltage reflection coefficient is described. The system is assembled from commercially available components and operates automatically from 26.5 to 40 GHz using a nominal 5 mW source. The paper also describes the means adopted to produce this broadband performance and the calibration method employed.

DOI:10.1049/ip-h-2.1985.0016

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Asymptotic eigenvalue distribution functions have been used in physics to approximate the actual frequency distribution of modes in resonant cavities. Certain versions of these formulas have been incorrectly applied to microwave cavity problems in engineering. A brief review of the relevant physics literature is presented along with some of the important results which should be used in engineering calculations. Also presented are the results of experimental measurements (on rectangular cavities), which verify the physical theory at microwave frequencies. Several features of the exact and approximate mode distributions become evident from this study, and these are discussed with respect to microwave cavity design.

DOI:10.1049/ip-h-2.1985.0017

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The purpose of this paper is to review, from a practical viewpoint, analytic gain-bandwidth theory and commercially available CAD techniques as applied to matching problems. Modern approaches and so called real frequency techniques to gain bandwidth problems are summarised to provide the necessary background for the reader to gain easy access to the relevant literature.

DOI:10.1049/ip-h-2.1985.0018

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A transmission line model for microstrip configurations, for which separation of variables is possible, is presented. For this, the patch is modelled as a transmission line joining the radiating apertures. Each section of the transmission line is replaced by a π-network. The effect of apertures in the direction perpendicular to the direction of propagation is included through the complex eigenvalues. The effect of mutual coupling between the radiating edges can be described using variational technique and finally incorporated in the equivalent circuit of the structure. Application of the transmission line method appears to be large. Some patch shapes have been analysed and others indicated.

DOI:10.1049/ip-h-2.1985.0019

出版商:IEE    

年代:1985

数据来源: IET

摘要:

Measurements of diplexers, lenses and feed horns for the frequency ranges 220–230 GHz and 460–495 GHz are reported, with particular emphasis on component insertion losses. At both frequencies best results are obtained using polarisation diplexers and Teflon lenses. Scalar feed horns are clearly preferable at 230 GHz whilst technological problems appear to indicate that simpler horns (dual mode, pyramidal) should be used at higher frequencies.

DOI:10.1049/ip-h-2.1985.0020

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The problem of locating and identifying objects (or persons) requires the system that has been designed using a small card carried by the object. When the object crosses the region of the high-frequency electromagnetic field created by a signal emitter, the card sends back a signal carrying a code characterising the object. The card is expected to be passive, and the code generator circuit is supplied by the microwave signal rectified on the card. In the paper the microwave rectifier realised by microstrip technology will be introduced. The nonlinear methodology studied here has given good agreement with the rectifiers using the Schottkybarrier diode at the frequency of 1.25 GHz. This methodology allows rectifiers to be created which give a direct voltage of more than two volts with input power of about ten milliwatts, and power efficiency of more than 85%.

DOI:10.1049/ip-h-2.1985.0021

出版商:IEE    

年代:1985

数据来源: IET

摘要:

A dual-offset reflector with a foam dielectrics cone feed and a shaped subreflector is described. The antenna is designed to receive signals from direct broadcast satellites. It combines a compact design with a relatively high efficiency and low sidelobes. The paper describes the theoretical design procedure, including the shaping of the subreflector which corrects for distortions introduced by the dielectric cone. A 12 GHz model is described which has been built and successfully tested.

DOI:10.1049/ip-h-2.1985.0022

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The problem considered is that of determining the induced current on, and field scattered by, a two-dimensional, flat, perfectly electrically conducting strip, which is edge loaded by a dielectric cylinder of circular cross-section. The strip is orientated radially with respect to the centre of the cylinder, and can be located outside, inside, or partially inside and partially outside the cylinder. The structure is excited by a plane-wave polarised transverse magnetic to the cylinder axis. A system of two coupled integral equations is derived for the current density on the strip in the presence of the cylinder, and is solved numerically by the method of moments. A series acceleration technique is devised to improve the convergence of the series incorporated in the kernels of the integral equations. Sample results are presented which illustrate how the current induced on the strip, the far field, and the radar cross-section are affected by the presence of the dielectric cylinder.

DOI:10.1049/ip-h-2.1985.0023

出版商:IEE    

年代:1985

数据来源: IET

摘要:

The problem of a vertical wire antenna placed above a flat lossy ground is formulated analytically in terms of the electric-field type (Pocklington-type) integral equation for current distribution on the antenna. The low-frequency approximation to the Sommerfeld integral appearing in the kernel of the equation is employed in the formulation. A numerical solution is obtained by the use of the piecewise sinusoidal Galerkin method, and the results are compared with those derived from the reflection-coefficient method and with available experimental data. The comparison shows a potential usefulness of the low-frequency approach.

DOI:10.1049/ip-h-2.1985.0024

出版商:IEE    

年代:1985

数据来源: IET