摘要:

The pulse wave propagation is theoretically investigated in a particular case of a medium of discrete random scatterers. As the basic equation the ordinary space‐time transport equation is used under the forward scattering approximation and is solved by means of the eigenfunction method developed in a recent paper. One of the major results is that an explicit expression of pulse intensity is analytically obtained for the realistic scattering amplitude, valid when the size of scatterers is sufficiently large in comparison with the wavelength. The dependence of pulse width broadening on the particle characteristic is also clarified for the case of large optical distances and is compared with that of previous literature. By the same techniques the temporal angular broadening of pulse wave is evaluated in order to find the conditions of applicability of the present metho

ISSN:0048-6604    

DOI:10.1029/RS015i005p00893

年代:1980

数据来源: WILEY

摘要:

Expressions have been derived for the magnetic field in air produced by a buried horizontal loop of arbitrary shape. Numerical results are presented for both circular and rectangular loops. Rectangular loops produce an azimuthal magnetic field component which is not present in the case of a circular loop. The results have application to source location in mine rescue techniques. In such cases, frequencies in the audio range are employed, and the assumption of a uniform current in the source loop is well justified.

ISSN:0048-6604    

DOI:10.1029/RS015i005p00903

年代:1980

数据来源: WILEY

摘要:

An alternative to the classical methods of analysis of linear antenna systems is proposed. The practice of solving an integral equation directly for an unknown current distribution is replaced by that of solving an integral equation for an unknown intermediate function. This intermediate function is shown to be the forcing function of a differential equation whose closed‐form solution yields the unknown current distributions. Numerical results based on the method and contained in this paper compare favorably with those of other investigators both theoretically and by measurement. The method exhibits a convergence rate far superior to that of the classical Pocklington formulation when simple approximating functions and point matching are used, yet the flexibility of the Pocklington formulation is retained. The method is well behaved numerically and convenient for computatio

ISSN:0048-6604    

DOI:10.1029/RS015i005p00913

年代:1980

数据来源: WILEY

摘要:

The cutoff wave numbersknmand the field of two‐conductor, perfectly conducting wave guides are determined analytically. Three types of wave guides are considered: Eccentric circular conductors of radiiR1,R2and distancedbetween their axes, elliptic inner with circular outer conductor, and circular inner with elliptic outer conductor. The electromagnetic field is expressed in the first case in terms of circular cylindrical wave functions referred to both axes in combination with related addition theorems, while in the last two cases, both circular and elliptical cylindrical wave functions are used, which are further connected with one another by well‐known expansion formulas. When the solutions are specialized to small eccentricities,kdin the first case andh=ka/2 in the last two cases (whereais the interfocal distance of the elliptic conductor), exact, closed‐form expressions are obtained for the coefficientsgnmin the resulting relationsknm(d)=knm(0)[1 +gnm(knmd)2+ ···] andknm(h)=knm(0) [1 +gnmh2+ ···] for the cutoff wave numbers of the corresponding wave guides. Similar expressions are obtained for the field. Numerical results for all types of modes, comparisons, and certain generalizations are al

ISSN:0048-6604    

DOI:10.1029/RS015i005p00923

年代:1980

数据来源: WILEY

摘要:

In order to facilitate the numerical evaluation of the grating effects of imperfectly periodic layered media, we introduce the extended local wave number concept, and we describe how the reflected wave is determined from the spatial behavior of the extended local wave number. A numerical method based on this concept is presented, which proves to be useful for structures with more than ten layers with the nonuniform period. Numerical comparisons with the invariant imbedding approach show the validity and utility of the method. Two specific structures are analyzed using this method.

ISSN:0048-6604    

DOI:10.1029/RS015i005p00939

年代:1980

数据来源: WILEY

摘要:

A dual‐channel microwave radiometer that measures precipitable water vapor and cloud liquid was operated during the 1979 Severe Storms and Mesoscale Experiment (Sesame). Conventional retrievals of vapor in the presence of clouds with high liquid content were not satisfactory. To correct these retrievals, an adaptive retrieval algorithm is developed and applied to the Sesame data. During clear conditions, or conditions of light clouds, the new recoveries are quite close to those obtained by conventional statistical inversion; however, during heavy liquid‐bearing clouds the recovered vapor agrees better with radiosonde d

ISSN:0048-6604    

DOI:10.1029/RS015i005p00947

年代:1980

数据来源: WILEY

摘要:

It was first suggested by Morgan in 1960 that an island might serve as a naturally resonant VLF slot antenna. However, theoretical studies by Galejs and Staras suggest that the principal current path would not be, as hoped, the ocean looping around the ends of the island. Rather the current would be confined to a region of the order of 1 skin depth radius centered on the conductor coupling the VLF power to the island. This is in conflict with the recent observations of Morgan, who claims to have observed resonances in the impedance of Deception Island. It is suggested here that these resonances are in fact resonances of the transmission lines used to connect power to the island. A similar explanation is also offered for the peninsula resonances observed by Gould. With this interpretation the experimental data on island antennas is fully in agreement with the current theoretical predictions of Galejs and Staras.

ISSN:0048-6604    

DOI:10.1029/RS015i005p00959

年代:1980

数据来源: WILEY

摘要:

The contention by Wait (1979) and Barr (1980) that the resonance at 9.5 kHz observed at the input to the Deception Island feed line (Morgan, 1979) was due merely to reduced phase velocity on the feed line is disputed. Greatly reduced phase velocity occurs only when a line is buried or laid on smooth earth, but the line at Deception Island was laid over very rough and steep terrain, and a resonance at 60 kHz demonstrated that the phase velocity on the line was essentially that of free space.

ISSN:0048-6604    

DOI:10.1029/RS015i005p00965

年代:1980

数据来源: WILEY

ISSN:0048-6604    

DOI:10.1029/RS015i005p00969

年代:1980

数据来源: WILEY

摘要:

Two analytical methods for treating electromagnetic wave transmission over a multisection curved earth are compared. In the first method, the integral equation is reduced such as to yield sums of residue terms that turn out to be identical in form to the result obtained by a mode‐matching procedure. The approximations employed are similar only to the extent that waves reflected from the separation boundaries are neglecte

ISSN:0048-6604    

DOI:10.1029/RS015i005p00971

年代:1980

数据来源: WILEY