Title :
A study of HF field strength variation in India and its prediction
Author :
Lakshmi, D.R. ; Reddy, B.R. ; Sain, Mangal
Author_Institution :
Nat. Phys. Lab., New Delhi, India
fDate :
3/1/1994 12:00:00 AM
Abstract :
Measured field strength data pertaining to several HF broadcast transmissions monitored in India during 1987-90 has been analysed to study solar activity, local time and seasonal variations in the field-strength. Values tend to saturate at high solar activity levels when sunspot numbers are beyond 120. Variations in field strength have also been studied with varying ratios of operational frequency to maximum usable frequency (fop/MUF) and equivalent vertical frequency of the links. Based on this study a prediction method for HF field strength has been suggested for India. Comparison of values estimated using this technique has been made with actual measured field strength values for different HF transmissions for different months. This method is to be particularly suitable for field operators
Keywords :
field strength measurement; ionospheric electromagnetic wave propagation; radio broadcasting; radio links; radiowave propagation; solar activity; HF broadcast transmissions; HF field strength variation; India; equivalent vertical frequency; local time variation; operational frequency to maximum usable frequency ratio; prediction method; seasonal variation; solar activity; sunspot numbers; Broadcasting; Circuits; Electromagnetic wave absorption; Frequency; Hafnium; Ionization; Ionosphere; Laboratories; Monitoring; Time measurement;
Journal_Title :
Broadcasting, IEEE Transactions on
