The determination of usable frequencies in HF band over Turkey

ABSTRACT Ms. D. Thesis THE DETERMINATION OF USABLE FREQUENCIES İN HF BAND OVER TURKEY AzizeASLANER Fırat University Graduate School of Nature! and Applied Sciences Departmend of Physics 2005, Page: 51 The High Frequency band ( HF ) include in the interval ( 3-30 ) MHz. and it is the highest band which reflected from the ionosphere. The Usable Interval has been changing as depending on the ionospherics parameters with respect to daily, seosonaly and geographies status. Because of this, the determined time space will be communicated fort he determined time space need determining usable frequency band for determining of this space MUF and LUF should be determined by. tn this study, to obtain MUF values, the critical frequencies which are measured by B. U. Kandilli Observatory are used. MUF values are obtained by using Secant taw. The seasonal and dairy variation of MUF are examined. As result of, it can be say mat if The frequency of electromagnetic wave propagated to ionosphere is bigger man MUF, this wave pass through ionosphere and it can't go back Earth, if The frequency of electromagnetic wave is lower man LUF then this wave (