POLARIZATION OF IONOSPHERICALLY PROPAGATED WAVES
Abstract
The theory of wave propagation in the ionosphere, supported by experimental measurements, is used to demonstrate that regular amplitude variations in HF sweep-frequency oblique-ionogram one-hop rays - when linearly polarized receiving antennas are employed - are due to corresponding variations of the received wave polarization with radio frequency. Over quasi-longitudinal paths the rate of occurrence of these variations with frequency (at some instant of time) was found (using computer raytracing techniques) to increase with increasing radio frequency and path length, and with increasingly close alignment of the propagation path with the longitudinal component of the earth's magnetic field. In addition, this rate is shown to be proportional to the group propagation-time difference between the two magnetoionic wave components at a given frequency. This relation explains certain remarkable features of the rate of occurrence of the variations. Experimental measurements demonstrate that the position in the spectrum of the observed amplitude maxima moves with time in a manner consistent with individual-mode polarization rotation with time at a given frequency. An experimentally determined statistical description of this behavior is obtained for winter-noon conditions. Polarization fluctuations of received ionospherically propagated waves are proposed as potentially useful indicators of the occurrence and location of ionospheric disturbances.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1967
- Accession Number
- AD0663707
Entities
People
- Mark Robert Epstein
Organizations
- Stanford University