[en] Recent experimental results have shown that the VLF ducts extending high in the magnetosphere are terminated at the base of the protonosphere and the VLF waves emerging from these ducts are propagated downward in the nonducted mode of propagation. In this paper, results of the ray tracing computations carried out with a specific purpose of examining the conditions under which these partly nonducted waves are observed on the ground, are presented. The results show that, for ground observations, it is necessary that the waves should emerge from the ducts at a definite wave normal angle. This wave normal angle is well in the range of total wave normal angles which the ermerging waves may conceive at the base of the ducts at middle and high latitudes but lies outside the range at low latitudes. Various results related to whistler activity on the ground are discussed in the light of these results

[en] Terrestrial radiation measurements obtained with planetary radio astronomy experiments on Voyager-1 and -2 during the early portions of each flight show the signals to be predominantly left-hand circularly polarized. Since these emissions were most probably generated above the Northern Hemisphere auroral zone, it is concluded that the radiation is emitted primarily in the extraordinary mode

[en] Full text: Influence of size of granule ZnO on spectrums of diffusive reflection in the range 165-900 nm has been investigated. fringe edge of shift absorption and decrease R_do (increases absorption T_r) long-wave region with decrease of range of granule, which is connected with influence of surface field synthetic irradiation.

[en] The paper highlights the ELF EMF radiation safety assessment performed at an overhead 275-kV High-Voltage Transmission Lines (HVTL). The study comprised of assessment performed at three (3) different transmission lines. The instrument setup and measurement protocols during the assessment were adopted from standard measurement method and procedures stipulated under the Institute of Electrical and Electronics Engineers (IEEE) Standard. The results were compared with the standards recommended in the International Commission on Non-Ionizing Radiation Protection (ICNIRP) guidelines. The results showed that the measured electric and magnetic field strengths were within the permissible exposure limit. Both the field strengths were found to drop significantly against distance from the transmission lines where closer distances showed higher field strengths. (author)

[en] The results of an experiment on the action of low-frequency radiation on the magnetospheric plasma are presented. Such action stimulates precipitation of protons. A preliminary interpretation of the data is given

[en] Vehicle-mounted antennas used for wireless communications generally operate at a power level of three watts or less. These wireless antennas are typically mounted on the roof, trunk, or rear window of a particular vehicle. For this project the radio frequency radiation level from the vehicle-mounted antennas were conducted by using Spectrum Analyser SRM 3006 with the frequency range from 27 MHz-3 GHz. The monitoring is carried out on 10 selected vehicles based on 3 different radio channels with different frequency modulation. The data obtained were compared to the guideline set by the International Commission on Non-Ionizing Radiation Protection (ICNIRP 1998). (author)

[en] Workers in the pulsation field entered the period of the International Magnetospheric Study (IMS) with a lot of theories that needed testing. Because of this and the wealth of new data available from the IMS observational campaigns, many new observational results have emerged from the IMS. The experience of the IMS shows us that the most fruitful method of working has been small-scale collaborations, between either a few individuals or a few groups with complementary data sets. The larger, more formally organized workshops do not seem to have been as successful in producing results, though they may have fostered useful contacts. In the years to come I hope and expect to see more of this sort of small-scale collaboration; especially as the initial results obtainable from a single data set are now published, experiments should turn to seeing how their data can be used in conjunction with other data sets. I also feel that the time is ripe for more theoretical work. The IMS has left us with a lot of new observations that need explanation

[en] An analysis of the dynamic spectra of the Jovian DAM emission (1.3--40 MHz) has been made from Voyager data; it appears that the different Jovian 'sources' can be defined by spectral chaaracteristics, rather than by occurrence probability. The non-Io emission consists of two families: vertex early arcs (VEA) and vertex late arcs (VLA). These two families are superimposed at all longitudes, but one is always more intense than the other. The characterics of the two families are specified; in particular, it is shown that the VEA family is more stable in time than the VLA family. The Io-controlled emission consists of the four sources already known from the ground-based observations in addition to a new source (Io-A')sp, identified by its dynamic spectrum alone. All of the sources are partially superimposed on non-Io emission. The (Io-B)sp and (Io-A')sp sources are made up of low-curvature arcs having low-frequency limits above 5 MHz. The high-frequency limit of the (Io-B)sp source is strongly modulated by Io-phase. The (Io-A)sp source has a specturm similar to the non-Io VLA emission. The other two sources, (Io-C)sp and (Io-D)sp, are not structured into well-defined arcs. A comparsion is made between the occurrence of these sources in the Io-CML plane with the sources defined from ground observations by probability of occurrence. Local time effects are observed only in the non-Io emission when compared before and after encounter. Before encounter, the VEA family is very weak and the VLA family very intense. After encounter, the opposite effect is observed. The Io-controlled sources are not affected by these local time effects

[en] Interactions in the magnetosphere between man-made whistler mode waves and electrons can produce either an enhancement of the wave or the generation of waves at a different frequency. Furthermore, natural emissions can be frequency shifted or modified by a nearby transmitter signal. Injection of extremely low frequency waves into the outer magnetosphere was initiated in 1978 in Norway by both the University of Paris and The Aerospace Corporation. The antenna is a 10.6-km power line tuned to the transmitted frequency. The University of Paris used a 1-kW transmitter to drive the antenna with a maximum current of 8 A. The Aerospace Corporation used the transportable very low frequency transmitter with a typical antenna current between 20 and 45 A. Experiments were conducted at times when the GEOS 2 and SCATHA satellites were near the magnetic meridian of the transmitter. The transmissions consisted of either a keyed fixed frequency or continuous waves swept in frequency. Emissions correlated with the transmissions were detected by the satellite receivers on several dates. Although the satellites were within a few degrees of the magnetic meridian of the transmitter, emissions influenced by the transmissions are seen during only a small fraction (<10%) of the total transmission time. With the first type of transmission, signals similar to power line harmonic radiation were recorded. Artifically stimulated emissions are also likely to have been triggered. Both types of transmissions triggered or enhanced hiss at a constant frequency during fixed-frequency transmission and at a variable frequency during a swept-frequency transmission. During swept-frequency transmissions there occurred two examples of natural emissions shifting in frequency by the man-made signal. Electron cyclotron harmonic emissions also appear to have been studied in frequency by the man-made signal

[en] An observed association of long period fadings of the field strength of LF radio signals with major meteor showers as also with high geomagnetic activity suggests a correlation between the meteoric and magnetic phenomena. The correlation is studied by using auroral electrojet indices and the incidence of meteor showers for a period of four years. The results indicate a significant correlation between the meteoric and magnetic activity. A critical examination of these results suggests that the ionized debris of meteors dumped into the polar region, besides producing geomagnetic disturbances, may also cause a localized enhancement of temperature of the polar atmosphere. This localized source of high temperature may, in turn, cause internal atmospheric gravity waves which travel to lower latitudes and produce the observed long period fading of the LF radio signal during major meteor showers