NOPR Collection:

TEC Enhancement during Periods of Major Meteor Showers

2016-10-28T11:17:25Z

Title: TEC Enhancement during Periods of Major Meteor Showers Authors: Lokandaham, B.; Yellaiah, G; Tyagi, T R; Singh, Lakha Abstract: The enhancement in TEC during the periods of some mail meteor showers is estimated utilizing the 136 MHz ETS-II Faraday rotation measurements carried out at Hyderabad (1.5ᵒN, 78.3ᵒE), a low latitude station. The Geminid meteor shower produced maximum enhancement (about 40 per cent) compared to other showers. These observations show that there is a definite contribution to TEC of the ionosphere due the ionization produced by the meteors during the shower period. Page(s): 114-116

Propagation of Transionospheric Radio Beam Waves through a Turbulent Layer

2016-10-28T11:07:51Z

Title: Propagation of Transionospheric Radio Beam Waves through a Turbulent Layer Authors: Mohan, Mahendra; Banerjee, P K; Reddy, B M Abstract: The problem of trans ionospheric radio waves propagating through a turbulent layer has been studied and analytical expressions for beam-wave wander and spread have been derived with the power-law spectrum of ionospheric irregularities by using phase screen model. The beam-wave spread has been found to be dependent, among other parameters, on the spectral index of the power-law spectrum. Some numerical computations have been carried out to estimate the possible beam-wave spread for SROSS. Page(s): 108-113

Troposcatter Link Design Using Air-borne Microwave Refractometer Observations over Kanpur

2016-10-28T11:06:12Z

Title: Troposcatter Link Design Using Air-borne Microwave Refractometer Observations over Kanpur Authors: Sarma, S B S S Abstract: In a troposcatter system, the received power is determined by the intensity and scale of the refractive index fluctuations in the path, especially the "common volume" of the transmitting and receiving antenna beams. Fine structure of the radio refractivity information was collected over Kanpur for winter conditions, using the air-borne microwave refractometer developed by the author. This information was used to design an optimum troposcatter link and the results are compared with the empirical relationships obtained by making use of radiosonde observations. Refractometer observations resulted in a gain of 35 dB in path loss which has reduced the power requirement of the transmitter considerably and hence the cost reduction. Use of radio refractive fine structure information collected by air-borne microwave refractometer in the design of a troposcatter communication link has resulted in optimization of the link and reduced the long distance electromagnetic interference on other circuits. Page(s): 103-107

IEC Near the Peak of the Equatorial Anomaly in Indian Zone during Solar Maximum

2016-10-28T11:02:26Z

Title: IEC Near the Peak of the Equatorial Anomaly in Indian Zone during Solar Maximum Authors: Modi, R P; Iyer, K N Abstract: Ionospheric electron content (lEC) measurements using Faraday rotation technique from Rajkot (lat. 22.3° N; long. 70.7°E; subionospheric dip latitude 16.5° N) near the peak of the equatorial anomaly for the last solar maximum (1980) are reported. The diurnal variation shows tendency for the post-sunset enhancements in IEC during equinox and winter. The winter daytime IEC values are ~29% higher than the summer values indicating seasonal anomaly. Results are compared with similar measurements in low solar activity condition. The IEC variations are also compared with N_max variations from nearby (Ahmedabad) ionosonde data. The day-to-day variability of IEC is also studied. The results are discussed in terms of the effect of E x B drift on the diurnal variation of the IEC during high sunspot condition and composition changes contributing to seasonal changes of IEC and slab thickness. Page(s): 98-102