Arrival Of Radiation Research Articles

Dual polarization receiving antenna array for recording of ultra-wideband pulses

The results of investigation of a 4 × 4 ultra-wideband dual polarization receiving antenna array designed for investiagtion of the polarization structure of nanosecond and subnanosecond electromagnetic pulses are presented. The elements of this antenna array are the crossed dipoles whose arms are loaded with single-stage FET amplifiers. The results of measurements of the patterns, the effective length, and the wave-forms of the recorded pulses are presented for different values of the array interelement spacing and the directions of arrival of radiation.

Image frequency suppression in frequency-scanned direction-of-arrival estimation systems

A novel signal processing approach to the problem of image frequency suppression in wide-band frequency-scanned radio frequency (RF) receiving arrays that employ digital signal processing (DSP) techniques to estimate the direction of arrival (DOA) of incoming radiation has been presented. The conventional approach to image rejection in RF receivers is to employ a front-end RF tuner before downconversion to the intermediate frequency. As DOA processing employs a separate receiver channel for each array element, an RF tuner would be needed behind each element. Clearly for scanned systems at microwave frequencies, this is not a viable option where the tuners would generally have to be implemented in RF hardware. The need for RF tuners can be eliminated by downconversion down to baseband and employing I&Q mixers, which provide an intrinsic image rejection capability. Unfortunately, such a solution requires two analog-to-digital (A/D) converters per array element. An alternative approach is to use image rejection mixers in which case only one A/D converter per array element is needed. The approach also requires only one A/D per array element but achieves the image rejection through a DSP implementation. As a result, use of relatively expensive image rejection mixers is avoided without sacrificing performance. Experimental results are presented that validate the theoretical predictions.

放射線計数率計出力のしきい値到達のシミュレーション

放射線計数率計出力のしきい値到達のシミュレーション

Application of schlieren methods in recording weak variations of the intensity of coherent optical radiation in the atmosphere

The results are given of applications of knife-edge and amplitude-grating schlieren methods in an analysis of variations of the intensity of coherent optical radiation in the troposphere. An experimental analysis of the fluctuations of the angles of arrival of laser radiation under various conditions is also reported. It is shown that the sensitivity of the knife-edge method in recording weak variations is higher than the sensitivity of direct recording.

Use of a position-sensitive photodiode to record the angle of arrival of optical radiation

Use of a position-sensitive photodiode to record the angle of arrival of optical radiation

Investigation of the fluctuations in the angles of arrival of laser radiation in the surface layer of the atmosphere

The fluctuations in the angles of arrival of a laser beam along a route 1200 m in length are investigated experimentally. The aperture dimensions of the transmitting and receiving devices and the beam geometry were varied during the measurements. The results obtained are compared with the results obtained by simultaneously determining the fluctuations in the angles of arrival of the radiation from a source of spherical waves. It is shown that the angles of arrival have a normal distribution. The dispersion of the angles of arrival depends on the diameter of the receiving aperture raised to the power -1/3 and increases as the angular aperture of the beam is reduced, becoming greater than the dispersion of the angles of arrival of spherical waves.

Auroral Effects and Excess Energy Electrons

AURORAL displays are usually attributed to increased leakage of electrons from the outer radiation belt. The mechanism responsible for this increased leakage is not yet understood, but the leakage is known to occur following the arrival of corpuscular radiation from the Sun. The time delay between solar eruptions and the onset of auroral phenomena shows that any solar electrons involved must have energies below 100 eV. Because, on the other hand, auroral electrons typically have energies in the range of several tens of keV, an electron acceleration mechanism must exist, presumably within the radiation belt. The purpose of this communication is to point out similarities between auroral effects and laboratory observations of electron leakage from a magnetic mirror, accompanied by electron acceleration, and to suggest that the same basic mechanism may play a part in both cases.

The production of cosmic radiation by a solar flare on August 31, 1956

It is shown that the neutron counting rates observed by three widely separated recorders increased by approximately two percent about half an hour after the observation of an intense solar flare at 1226 U.T. on August 31, 1956. The event, as observed at all three stations, exhibited the abrupt onset, and gradual recovery typical of solar flare effects. The time delay between the first visual sighting of the flare, and the earliest arrival of cosmic radiation at the earth was about 20 min. It is shown that the quantity of cosmic radiation which arrived at the earth was two to three orders of magnitude less than the quantities which arrived during earlier flare effects. Consideration of the temporal dependence of the small flare effect suggests that only a small quantity of cosmic radiation was produced in the solar flare.

A sense-finding device for use with spaced-aerial direction-finders

A simple method is described for the rapid determination at a receiver of the sense of the direction of arrival of radiation from any transmitting station. A radio bearing of the station taken in the usual manner wit a four-aerial Adcock direction-finding system, and a second observation ofminimum received signal is made after certain modifications to the electrical connections between the aerials have been effected by switching. The two observations are sufficient to determine without the usual ambiguity of 180° the bearing of the transmitting station at the receiver. The method is particularly suitable for use on high frequencies and with the visual type of receiver incorporating a cathode-ray tube.

A sense-finding device for use with spaced-aerial direction-finders

A simple method is described for the rapid determination at a receiver of the sense of the direction of arrival of radiation from any transmitting station. A radio bearing of the station is taken in the usual manner with a four-aerial Adcock direction-finding system, and a second observation of minimum received signal is made after certain modifications to the electrical connections between the aerials have been effected by switching. The two observations are sufficient to determine without the usual ambiguity of 180° the bearing of the transmitting station at the receiver. The method is particularly suitable for use on high frequencies and with the visual type of receiver incorporating a cathode-ray tube.