In this paper, rainfall effect on the VHF radio-wave propagation in a tropical forest is further studied in details. Theoretical study and experimental investigations are performed with the help of a four-layered model for forested environment. It is found that the lateral wave traveling along the air-canopy interface, the direct waves, and the ground reflected waves are the main modes for VHF ...

We present and analyze a gedanken experiment and show that the assumption that an antenna operating at a single frequency can transmit more than two independent information channels to the far field violates the Second Law of Thermodynamics. Transmission of a large number of channels, each associated with an angular momenta 'twisted wave' mode, to the far field in free space is therefore not po...

[1] The high time resolution observations obtained by the WAVES experiment of the STEREO spacecraft in solar type III radio bursts show that Langmuir waves often occur as intense localized wave packets. These wave packets are characterized by short durations of only a few ms and peak intensities, which well exceed the supersonic modulational instability (MI) thresholds. These timescales and pea...

Propagation of radio waves in the ultrarelativistic magnetized electronpositron plasma of pulsar magnetosphere is considered. Polarization state of the original natural waves is found to vary markedly on account of the wave mode coupling and cyclotron absorption. The change is most pronounced when the regions of mode coupling and cyclotron resonance approximately coincide. In cases when the wav...

The scattering of electromagnetic radiation by the particle gyrating in an external magnetic field is considered. Particular attention is paid to the low-frequency case, when the frequencies of incident radiation are much less than the electron gyrofrequency. The spectral and polarization features of the scattering cross-section are analyzed in detail. It is found that the scattering transfers ...

We have shown experimentally, in a real-world setting, that it is possible to use two beams of incoherent radio waves, transmitted on the same frequency but encoded in two different orbital angular momentum states, to simultaneously transmit two independent radio channels. This novel radio technique allows the implementation of, in principle, an infinite number of channels in a given, fixed ban...

1. A Discrepancy and Its Resolution.-The problem of the propagation of radio-waves along the surface of the (plane) earth was first treated in a celebrated paper by A. Sommerfeld (1909).1 Let the (r, (p)-plane of a cylindric system of coordinates coincide with the plane of the earth surface and let the z-axis point vertically upward. Sommerfeld considered a vertically oscillating dipole (radio-...

A strange notion exists that nuclear magnetic resonance (NMR) uses radio waves for both excitation of a sample and for the reception of signal. Where this idea originated is difficult to say, for it cannot be found in any of the basic, long-established texts. However, its acceptance within, at least, the medical imaging community is now nearly universal, and attempting to combat the weight of s...