NOPR Collection:

Studies on E-Region Drift & Anisotropy Parameters of Small-scale Irregularities at WaItair

2016-11-25T06:53:26Z

Title: Studies on E-Region Drift & Anisotropy Parameters of Small-scale Irregularities at WaItair Authors: Murthy, B Suryanarayana; Rao, B Ramachandra Abstract: A systematic study has been made on E-region drift and anisotropy parameters during Nov. 1970-Mar. 1972 using simultaneous amplitude and phase-path records taken on a frequency of 2.4 MHz. Phase-path records are used to select best samples of the fading records, so as to minimize the errors that are inherent in the fading records. The results are compared with earlier investigations. Page(s): 196-198

Non-linear Interaction of Electromagnetic Waves in the Ionosphere

2016-11-25T06:51:11Z

Title: Non-linear Interaction of Electromagnetic Waves in the Ionosphere Authors: De, S S Abstract: Non-linear interaction of electromagnetic waves within the ionosphere has been investigated theoretically using derivative expansion technique. The shifts in frequency and wave number are seen to increase when the medium is excited with waves of more than one frequency unlike the situation reported by Nayfeh [Phys. Fluids, 8 (1965), 1896]. Possible regions of interaction are being studied through numerical computations. Page(s): 194-195

Electronic Collision Frequency in the F Region at Sunrise & Sunset

2016-11-25T06:44:17Z

Title: Electronic Collision Frequency in the F Region at Sunrise & Sunset Authors: Dubey, R C Abstract: The variation of the effective collision frequency of electrons veff with solar zenith angle has been studied around sunrise and sunset by group retardation method [Appleton, E. V., Nature, Lond., 135(1935), 618] at different radio frequencies. The variation is found to be steeper at sunrise than at sunset. Taking a linear relationship between 'veff' and f², the square of radio frequency, a rough estimate of the electron temperature T_e has been made. The resulting values of T_e at sunrise and sunset are found to be 1113 and 987^o K., respectively. Page(s): 193-194

Tropospheric Radiowave Propagation over Diffraction Paths

2016-11-25T06:40:02Z

Title: Tropospheric Radiowave Propagation over Diffraction Paths Authors: Swarup, S; Kumar, V; Ahmad, A Abstract: Measurements of field strength for a period of one year were made over two paths in vhf band. One path (55 km) has two intervening ridges of Shivalik range and the other is a diffraction path (35 km) over curved earth. Distributions of hourly median values of one year data for both links are presented in the form of probability curves. Seasonal, monthly and diurnal variations of field strength have also been studied. The results of observations have been compared with theoretical and CCIR predictions. Page(s): 188-192