摘要:

The use of higher resonant modes, other than tradiationally used TE011is discussed in connection with the so-called Courtney method of measuring the relative dielectric constant of dielectric resonators. An error analysis is developed, which takes into account also the presence of an airgap between the dielectric resonator and the two parallel metal plates.

DOI:10.1049/ip-h-2.1986.0045

出版商:IEE    

年代:1986

数据来源: IET

摘要:

A circular cylindrical cavity is loaded with a dielectric sleeve which has a length shorter than that of the cavity. In general, the unloaded sections of the cavity can be such that the pure H11mode is either propagating or cutoff at the resonance frequency of the loaded cavity, but the emphasis in the paper will be on the cutoff case. An electromagnetic model of this cavity structure is developed using the modal-matching method. The possibility of using the cutoff version of the sleeve-loaded cavity for stabilising the frequency of a microwave solid-state oscillator is investigated experimentally.

DOI:10.1049/ip-h-2.1986.0046

出版商:IEE    

年代:1986

数据来源: IET

摘要:

In the paper, the asymmetrical coupled coplanar-type transmission lines (C-CTLs) are investigated. The analytical method for the general structure of asymmetrical C-CTLs with anisotropic media is presented, based on the quasistatic and the hybrid-mode formulations, for the first time. The line characteristics of interest, e.g., the propagation constants and the characteristic impedances, of the various types of C-CTLs with anisotropic substrates are also presented.

DOI:10.1049/ip-h-2.1986.0047

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The half-wave HE111open ferrite or dielectric resonator, open circuited or loaded by image walls at each end, is a common building block in the construction of waveguide circulators and other devices. Its resonant frequency is usually evaluated by catering for the image wall effect but neglecting that of the open lateral wall. The latter omission is largely reconciled in this paper by employing an equivalent waveguide model for the resonator which has the same radius as the original but with an effective instead of the constitutive dielectric constant. The import of the diagonal elementμdof the demagnetised resonator is separately catered for.

DOI:10.1049/ip-h-2.1986.0048

出版商:IEE    

年代:1986

数据来源: IET

摘要:

In the ideal case, a symmetrical five-port junction, together with a directional coupler, forms one of those few six-port networks that satisfy the criteria for optimum six-port reflectometer performance. Imperfections however exist in the actual hardware, and they degrade the performance of this otherwise ideal circuit. Although the six-port technique accounts for these imperfections globally in the calibration procedure, it is nevertheless important that a proper analysis of how the system degradations arise be made. The paper provides such a theoretical study. In the course of the investigations, it was found that improvements in the performance of the hardware circuit may be obtained simply by re-arranging the inter-connections among the constituent components.

DOI:10.1049/ip-h-2.1986.0049

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The ray trace equations for a dielectric lens reflector with a tilted linear front surface are derived, and the reflecting profile obtained. A thin lens results when the angle of tilt is such that the lens reflector has zero thickness at the apex. It is found that, for fixed radius and maximum subtended angle at the focus, the reflecting profile is approximately constant with angle of tilt and can, to the same approximation, be constructed from circular arcs.

DOI:10.1049/ip-h-2.1986.0050

出版商:IEE    

年代:1986

数据来源: IET

摘要:

Two-dimensional window functions and their Fourier transforms are widely used in electromagnetics and optics. It is shown that the two-dimensional Fourier transform of a window function can be written as a line integral along the boundary contour of that window function. This reduction of the two-dimensional Fourier integral to a one-dimensional line integral is attractive for both the closed-form and numerical evaluation of the Fourier transform of complex shaped window functions. Some applications of this new evaluation method are discussed.

DOI:10.1049/ip-h-2.1986.0051

出版商:IEE    

年代:1986

数据来源: IET

摘要:

It is shown that the inverse Laplace transform of the Fourier domain reflection coefficient of a layered medium can be easily derived by performing the Mittag-Leffler expansion. Thus exact image theory can be used in field calculations. The radiation pattern is readily deduced from the image functions and the surface wave is also deduced from the field integrals. As applied to microstrip structures, the asymptotic approximations agree with the Sommerfeld formulas.

DOI:10.1049/ip-h-2.1986.0052

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The radar cross-section of a thin dielectric ellipsoid of arbitrary size is derived. The solution is obtained by employing a quasistatic approximation to find the field inside the ellipsoid. Techniques described in the literature were used to determine the fields scattered by the ellipsoid in the far zone. The scattered-field relationships were then used to obtain the radar cross-section equations in closed form. The solution for the radar cross-section obtained in this manner was compared with available results in the literature and agreement was found.

DOI:10.1049/ip-h-2.1986.0053

出版商:IEE    

年代:1986

数据来源: IET

摘要:

The paper presents a short review of the theoretical solution for the problem of the interaction between electromagnetic radiation and rain in the frequency range 10–100 GHz together with some experimental results. The raindrop shapes are assumed to be spherical. This approximation is considered valid for the small diameter raindrops which are the most important at millimetre wavelengths. Particular attention is devoted to the effect of the raindrop-size distribution on rain induced attenuation, and a comparison is made between the theoretical prediction for attenuation and phase dispersion using the Laws and Parsons and the log-normal raindrop-size distributions. Rain-induced attenuation measurements were made simultaneously at 36 GHz and 55 GHz on a common 4.1 km link and are presented for isolated rainfall events as well as in a statistical form for two separate periods of 12 and 17 months. The measurements are compared with the Laws and Parsons and the log-normal raindrop-size distribution predictions. Comparison is also made with attenuation measurements made on the same path at 36 GHz and 110 GHz.

DOI:10.1049/ip-h-2.1986.0054

出版商:IEE    

年代:1986

数据来源: IET