T. Ishizone

Measurement of antenna current distribution in an anisotropic plasma

The current distribution along a cylindrical antenna immersed in a magnetized plasma has been measured. It has been observed that the standing wavelength along the antenna wire is substantially shortened to a greater degree with increasing plasma frequency under the presence of the dc magnetic field. The gyroresonance has also been observed in the current distribution.

Electromagnetic wave propagation along a conducting wire in a general magnetoplasma

The propagation constant of the electromagnetic wave along a very thin conducting wire immersed in a magnetoplasma is obtained explicitly for a general case where the dc magnetic field is applied with an arbitrary inclination with respect to the wire.

Radiation characteristics of spherical triangular array antenna

Radiation characteristics of a type of spherical triangular array composed of turnstile elements are numerically analyzed and discussed. It is found that the spherical array proposed here is able to scan its beam up to large angle without variation of the directivity and the circular polarization property.

Reciprocity relations in an isotropic compressible multifluid plasma

Reciprocity relations in an isotropic compressible multifluid plasma with collisions are theoretically investigated. The reciprocity theorem for current sources and electromagnetic fields which is often employed for a free space is found to be guaranteed in such a medium. The reciprocity is shown to be valid also for the case that an antenna is surrounded by an abrupt vacuum sheath under a physically permissible boundary condition. Furthermore, the reciprocity theorem is established for electric charge sources and number density of wave perturbed particles under the condition that there is no collisions among perturbed particles of different species. It is also shown that the similar reciprocity relation holds for the quasistatic approximation without any restrictions. Finally, as an application of the reciprocity theorem, a general expression giving antenna receiving voltages for incident electrostatic waves such as an electron plasma wave and an ion acoustic wave are obtained.

Measurement of the phase constant along a conducting wire in a magnetoplasma

The phase constant of the electromagnetic wave along a conducting wire in a plasma magnetized in parallel or perpendicularly to the wire has been measured. Fairly good agreement is found between the measured results and the theoretical prediction when the effect of the surrounding ion sheath is taken into account.

A simplified expression of the dyadic Green's function for a conducting half-sheet

Simple analytical expressions of the dyadic Greens function for a conducting half-sheet have been derived. These expressions involve some finite integrals which can be easily calculated by a digital computer and are much simpler than those involving the vector mode function expansion. Input impedances of monopole antennas on and near an edge of a conducting half-sheet and the impedance of a notch antenna have been obtained, and the usefulness of these simplified expressions has been proved. The present results can be applied to check the limits of the applicability of the asymptotic theories, e.g., the geometrical theory of diffraction (GTD) and the uniform asymptotic theory of diffraction (UAT).

Measurements of the transmitting and the receiving patterns of a dipole antenna for an electron plasma wave

The transmitting and the receiving patterns of a dipole antenna for an electron plasma wave have been measured by using the interference method. The results agree fairly well with the theoretical patterns that were predicted from the fluid model analysis and also experimentally prove the reciprocity relationship between the transmitting and the receiving patterns, which is theoretically found to be valid in the plasma wave approximation. The characteristics of the transmitting and the receiving efficiencies versus the dc bias voltage applied to the dipole antenna have been also experimentally investigated.

Sheath effects on the current distribution along an antenna in a plasma

The sheath effects on the current distribution along a cylindrical antenna immersed in a plasma have been investigated in two respects: 1) the measurement and its interpretation of the current distribution of the antenna in the region of f > f_{p} ( f_{p} is plasma frequency) when its dc bias voltage is varied; 2) the observation and its interpretation of the slow-wave mode along the antenna in the region of f .