Polarization-Angular Dependences of the Reflection and Transmission Coefficients of Free Plates of Quasi-Anisotropic Ice in the L-Range

Abstract

The polarization-angular dependences of the reflection and transmission coefficients of free plane-parallel ice plates in the region of 0°С, when flat electromagnetic waves of s-and p-polarization fall on them and are recorded by an L-band radiometer 1.41 GHz are studied theoretically. It is shown that the observation of interference effects in ice plates in the L-range is limited to a plate thickness of 4.3 meters. This limitation is due to a radiometer bandwidth of 20 MHz. Ice is considered an isotropic or uniaxial crystal with an anisotropy coefficient of 15%. Three types of directions of the anisotropy axis are considered in the assumptions of the quasianisotropic medium model. The value of the Brewster angle is obtained, and it is shown that it does not depend on anisotropy. Reflective and anti-reflective effects are associated with a change in wavelength in the direction perpendicular to the surface of the plate. In turn, this length depends on the angle of incidence, polarization, and direction of the anisotropy axis. The possibility of forming interference regions of transparency for certain thicknesses is shown, the reflection coefficients for both polarizations are significantly reduced, and the transmittances increase. Interference areas of transparency can be formed both at the Brewster angle and at other angles. These effects are associated with interference phenomena and their enhanced effect of anisotropy.

Calculation of the intrinsic thermal radiation of plane-parallel quasi-anisotropic multilayer plates with smooth boundaries

“…In the considered range of parameters, these properties of an ideal radiometer are close to the properties of real radiometers used in [23][24][25] The new algorithms being developed are very complex and it was supposed to check them by exact reproduction of the rather interesting result obtained earlier in [19] before studying more complex cases. In accordance with the results of [19], at an isotropic ice thickness of 50 cm and a temperature near 0°C, there should be a transparency band at an angle of incidence of 30 degrees, for both polarizations simultaneously. The presence of ice anisotropy modifies the effects of bleaching and anti-bleaching near this transparency band.…”

“…For a multilayer plate, a system of linear equations was automatically formed, its solutions were Fresnel-Airy coefficients. The results of [16] were used in [19] for a theoretical study of the reflection and transmission coefficients of electromagnetic waves in the L-band (1-2 GHz) in free plates of isotropic and anisotropic ice. For the L-band, there are commercially available domestic [23,24] and foreign [25] radiometers used to monitor the Earth's ice cover using aircraft.…”

“…The possibility of generalizing formula (1) to multilayer quasi-anisotropic plates seems promising from the point of view of application in the field of remote sensing of both the earth's surface and other objects. In [19], the reflection and transmission coefficients of anisotropic free ice sheets at various thicknesses were discussed. The calculations were greatly simplified by the assumption that the planeparallel plate is free, i.e.…”

“…Microwave radiometers have certain limitations related to the properties of their antennas. It was shown in [19,21] that with an ice thickness of 4.2 m, the presence of a 2 MHz radiometer passband in the L-band leads to a complete smoothing of the inhomogeneity in the polarization-angular dependences of the reflection and transmission coefficients. With an ice thickness of 50 cm, the presence of the radiometer passband can be neglected at observation angles less than 70 degrees and the radiometer can be considered ideal.…”

“…The amplitude of p-polarization waves (s = -1) in [1] was considered the complex amplitude of the magnetic field lying in the plane of the plate. In [16,19] and in this article, the same approach is adopted.…”