When radio communication or propagation problems are discussed, an idealized understanding of the expression linear or circular (or, more accurately, elliptical) polarization is usually used. At the same time, in order to simplify any complicated problems, it is forgotten that even a linearly polarized wave propagating near the surface of a lossy medium changes its polarization to an elliptical one that is applied to measure the equivalent conductivity of the medium. In the case of multi-path propagation of a circularly (elliptically) polarized wave as a result of multi-path interference, a spatial rotation of the polarization plane may be observed. Thus, it may be called quasi-spherical or quasi-spheroidal polarization. Usually, such a situation occurs in the neighborhood of a complicated system of radiators (primary and secondary) when they are excited with an FM modulated signal or, for instance, as a result of changes in phase differences of the rays coming to a point of observation, due to frequency changes or Doppler effect.

Chapter Contents:

• 7.1 A Probe Composed of Linearly Dependent Elements
• 7.2 Spherical Radiation Pattern of an E/H Probe
• 7.3 A Probe Composed of Three Mutually Perpendicular Dipoles
• 7.4 Comments and Conclusions

Inspec keywords: electromagnetic wave propagation; radiocommunication

Other keywords: multi-path propagation; circularly polarized wave; multi-path interference; directional pattern synthesis; elliptically polarized wave; phase differences; linearly polarized wave propagation; Doppler effect; radio communication; radio propagation; FM modulated signal; quasi-spheroidal polarization; quasi-spherical polarization

Subjects: Electromagnetic waves: theory; Electromagnetic wave propagation