In radio frequency engineering, an overlap zone occurs where signals from two or more radio stations, transmitting at the same frequency, can be received with comparable intensity.[1] Interference occurs frequently in such a zone.[2]
In order to avoid this, a receiver with directional antenna is used, which can then be aligned in such a way that it will only receive the signal of one transmitter. Alternatively, the signals could be separated using a demodulator in single sideband mode.
With digital radio (Digital Radio Mondiale and Digital Audio Broadcasting being two common types), there is no interference in the overlap zone.[3]
1 - Multifunctional Ultrawideband Antennas Trends, Techniques and Applications By Chinmoy Saha, Jawad Y. Siddiqui, and Yahia M.M. Antar - 2019. P.3 - P.11 - P.46, 47 - P.65.