On the possibility of the existence of an additional “dead” zone, which should be taken into account in the private planning of shortwave radio stations

The paper presents the results of computational experiments showing the possibility of a situation in which the values of optimal operating frequencies of a short-wave radio line determined by known methods correspond, based on existing ideas about the reflection of radio waves from regular layers of the ionosphere, to a private range inaccessible for radio communication. The results of statistical processing of the data of computational experiments reflecting the probability of occurrence of such situations on radio lines, the range of which is close to the limiting range of single-skip propagation of ionospheric radio waves, are given.