by RP SINGH · 1980 · Cited by 3 — minimo che si nota differire da un materiale all’altro. Le caratteristiche della riflessione di onde elettromagnetiche di cui si è trattato in questa nota,

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Reflection characteristics of EM waves over homogeneous Earth model RAMESH P. SINGH (*) – TARKESHWAR LAL (*) Received on July 10th, 1980 ABSTRACT Theoretical analysis have been carried out to investigate the effect of subsurface electrical parameters such as resistivity and dielectric cons-stant; and angle of incidence on reflection coefficients for vertically and horizontally polarized electromagnetic waves. It is shown that the reflec-tion coefficients for vertically and horizontally polarized electromagnetic waves are strongly depedent on wave frequency and angle of incidence. At small angles of incidence the Ri, and Ris seen to go through a mini-num value which is seen to differ from one material to the other. Re-flection characteristics of electromagnetic waves discussed in this paper can be helpful in the accurate interpretation of geophysical data. (*) Department of Geophysics, Banaras Hindu University, Varanasi – 221005, INDIA.

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250 RAMESH P. SINGH – TARKESHWAR LAL RIASSUNTO Sono state eseguite analisi teoriche per indagare sull’effetto dei para-metri elettrici di sottosuperficie, come la resistività, la costante dielettrica e l’angolo di incidenza sui coefficienti di riflessione per onde elettroma-gnetiche polarizzate verticalmente e orizzontalmente. Si nota che i coeffi-cienti di riflessione per onde elettromagnetiche polarizzate verticalmente e orizzontalmente, dipendono strettamente dalla frequenza dell’onda e dall’angolo di incidenza. A piccoli angoli d’incidenza \’R,, e l’i?,, passano attraverso un valore minimo che si nota differire da un materiale all’altro. Le caratteristiche della riflessione di onde elettromagnetiche di cui si è trattato in questa nota, possono essere di aiuto per una più accurata interpretazione di dati geofisici. INTRODUCTION The electromagnetic wave propagation and interaction with various typesof earth’s material has been extensively studied. The reflection and attenuation of electromagnetic waves from the earth’s subsurface is cumulatively affected by the subsurface ma-terial and their electrical properties. The studies on electroma-gnetic field attenuation and change of reflection coefficient with frequency, polarization and angle of incidence play an important role inrevealing the subsurface electrical properties (Shivprasad and Stotz, 1972; Kozaki, 1970; Wait, 1971; Philippe, 1973; Lytle, 1974; Suzuki et al., 1975; Evans, 1977; Singh and Singh, 1979) employing transmitter receiver systems with large separations. These feature of received electromagnetic waves are primarily controlled by the dielectric constant (sr) and conductivity (170 KB – 11 Pages