摘要:

Diffraction techniques are used to predict the propagation path loss between a radio transmitter site and receiver sites located on flat land, in the shadow of mountainous and hilly terrain, near wooded areas and within several types of building structures. These predictions are used to determine the effective coverage range for a radio paging service and, in the reverse problem, are used to determine the required transmitter power and siting for a desired geographical coverage. Extensive field tests at over 50 sites and ranges to 50 km are summarized for comparison with predicted values.

ISSN:0272-6343    

DOI:10.1080/02726348708908161

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The theory and measurement of the electromagnetic correlation between orthogonal linearly polarized returns In two-channel precipitation radars is summarized. The relationship of the properties of precipitation particles to the cross-correlation as a function of polarization direction is discussed. Also considered is the relationship of correlation in a linearly polarized radar system to the corresponding circular polarisation characteristics. The formulation for the cross-correlation at linear polarization is extended to Include coverage of more general models of the distribution function for precipitation particle canting angle. Typical experimental results showing measured values of cross-correlation with rotating linear polarization are presented.

ISSN:0272-6343    

DOI:10.1080/02726348708908162

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A hybrid high-frequency formulation for determining the scattering characteristics of dielectric bodies has been developed using the principles of geometrical optics and Huygens equivalent sources. An application of the method to the problem of determining the near backscattered field due to once internally-reflected rays from dielectric spheroids is presented here, with particular consideration given to the dominating rear-axial and glory rays.

ISSN:0272-6343    

DOI:10.1080/02726348708908163

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The scattering of electromagnetic waves from axisymmetric bodies of lossy dielectric in the resonance region is considered. A theoretical formulation to the problem is used in terms of equivalent currents on the surface of the scatterer, leading to a set of surface integral equations which are solved numerically using the method of moments. The excitation is considered to be a circularly polarized plane wave at oblique incidence. Various sizes and shapes are considered which simulate ice, and for which experimental results of the backscattering matrix elements are available. The measurements and the computations are carried out at two different frequencies, 2.86 GHz and 9.6 GHz. Very good agreement between the numerical results and the experimental data is obtained for the backscattering direction. The numerical results of the forward scattering are also calculated and presented.

ISSN:0272-6343    

DOI:10.1080/02726348708908164

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

A survey of the inverse black body radiation problem is presented including a modification to the Hamid-Ragheb approximation which leads to a new approximate formula for the Planck's radiation law valid at all frequencies. The modified regime is useful in solving the inverse black body radiation problem in closed form. The absolute percentage errors in constructing the area-coldness distribution due to the proposed and previous approximations are presented. The results suggest that our modified approximation to Planck's law is more suitable than all other approximations at all frequencies.

ISSN:0272-6343    

DOI:10.1080/02726348708908165

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

The effect of a thin conducting sheet on the fields of a subsurface vertical magnetic dipole has been analyzed. The integral representation of the fields has been evaluated numerically, and numerical results for the vertical magnetic field above the source at the surface are presented in parametric form. It is found that the predicted fields give better agreement with previous transmission measurements than do the fields of a homogeneous half-space model.

ISSN:0272-6343    

DOI:10.1080/02726348708908166

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor

摘要:

When solving the diffraction problem of an electromagnetic wave incident on a half plane subject to a mixed boundary condition, the analysis can be simplified by using the field components normal to the surface. Although this is the procedure generally employed, it is shown that the Wiener-Hopf analysis may involve quantities whose edge singularities are non-integratable, and whose Fourier transforms do not exist in the classical sense. A method for overcoming the difficulty is presented.

ISSN:0272-6343    

DOI:10.1080/02726348708908167

出版商:Taylor & Francis Group    

年代:1987

数据来源: Taylor