Tohid Zargar Ershadi - K.N Toosi University of Technology
Seyed Vahab AL-Din Makki - K.N Toosi University of Technology
Farzad Pahlavani - Islamic Republic of Iran broadcasting

The aim of this research is to provide a solution for better night propagation of medium wave (MW) broadcast transmitters through pattern change, type of applied propagation and without creating essential changes in transmitters. Important propagation problems of MW especially at the night are (a) Co-channel interference of far transmitters at the night that (b) decreases Local Coverage (LC) at night in comparison with day. (c) To cause problems for those transmitters being Far Coverage (FC) area and (d) heavy traffic of MW band. Execution of proposed solution at this article causes economical savings and decreases number of transmitters as well as energy consumption. It also decreases Field Strength (FS) at the far area and the areas being out of LC and finally decreases undesirable interference

Sky Wave Propagation, Medium Wave Broadcast Transmitter, Night Coverage, Antenna Pattern