Some Type of Broad-Band Emission in the Hectometric Frequency Range Observed Within the Ionosphere*

A unique set of ionospheric radioemissions in the frequency range of 0.6-6.0 MHz has been registered on board of Intercosmos-19 satellite launched in 1979, i.e., during the peak of the last solar activity period. Many new characteristics of ionospheric radioemissions have been discovered in this set. In the above spectral range of emission the Intercosmos-19 data show the following features: If f_p lesssim 3 MHz and _FOF2 gtrsim 5.5 MHz, there exists a broadband enhancement centred on 4 MHz, reaching the level of about-82dB; the shape of this enhancement shows minor variation of the order of 3 dBm along the satellite orbit in spite of broad variations of f_p and _FOF2, if the mentioned relations between frequencies are fulfilled; usually if _FOF2 drops even to 3 MHz, the man made radionoises add independently to this enhancement - the enhancement is strongly modified when f_p increases above 5 MHz and its shape is related to the changes of f_p. These characteristics suggest the hypothesis on nonglobal origin on the observed broad-band emission. The aim of the present paper is to discuss this question.