One very interesting moment in operation from Ai-Petri mountain conditions was opened there. By me it was named "Ai-Petri effect" in antenna operation. Though Ai-Petri lies only on 1200 meters above sea level, clouds often stand on Ai-Petri. There permanently lower on Ai-Petri from the sky. By a wind them runs up till the plateau. It happens, that within 5 minutes the sun can shine, a cloud then will landed, will pass a rain, and then again sun shines.

If the cloud has seat on plateau, it is not bad. But, if the cloud has a seat on antennas, the operation of radio set becomes impossible. First, that thus descends - variation of antenna resonance frequency. That the inductivity of a cloud is essentially distinct from 1, when the cloud has a seat on an antenna, the electrical length varies. As a result of it descends detuning of an antenna. It descends for rather short time - two - three minutes. The current in to antenna for this time varies in some times! At first I thought, what is it descends because of poor contacts in an antenna socet, but then the reason of this phenomenon was explained, when I have left our shelter, and has seen, how the cloud on our antenna has seat, and has heard as the guys speak, that the propagation is gone.

I think, that in the receiver of the correspondent, our signal too considerably varied on force. But variation of antenna resonance frequency and antenna detuning has appeared only one of the sides of this unpleasant phenomenon. Other, more parasitic side of the Ai-Petri effect has appeared shielding by a cloud of our antenna. The cloud is charged negatively concerning ground surface (fig. 4). And at defined density of charged particles in a cloud there was a full shielding of reception. Some more minutes could be magnificent reception, and through a pair of minutes the reception on all ranges could be completely absent. This effect was watched at white clouds and mainly in daylight. At black, rainy clouds, the reception, though weak was present.

In night time of full termination of reception at the expense of clouds was not watched. But because of detuning of our antenna by a cloud and partial weakening of reception at the expense of shielding of cloud, the reception often was so unsatisfactory that it was impossible to work in either.

One more unpleasant effect, which was watched on landing of clouds on our antenna are in strong electrical noise. At white clouds, which screened reception, in the receiver a solid rattle crossing in singing, or strong white noise often was watched. If thus at antenna to approximate to radio set body from the antenna overshot sparks on to the body. In all my self-made transceivers and in my matching devices the "antenna output" electrically was grounded on ground. In a radio set R-143 the antenna was not electrically connected to transmitter body. As a result of it the operation of this radio set in conditions of a white cloud because of strong electrostatic interferences practically was impossible. The tangency to an antenna called electrical impact. Neon bulb, brought to antenna, shined.

It displays, as far as it is important to conduct antenna electrical grounding on the transmitter body in self-made gear. In my matching device and in my self-made transceivers the antenna current indicating device was installed. So sometimes, in time of especially strong white clouds, the current from a cloud between antenna and ground reached hundred milliamperes! It is understandable, that in these conditions to speak about any reception was completely senselessly.

Ai-Petri the effect has made me to refuse from directional wire antennas installation. Really, the majority of time Ai-Petri is coated by clouds. Therefore, the elements of directional wire antennas such as YAGI will be detuned, and to speak about any directivity diagram and about further service capability of these antennas it would be senseless. An antenna with the phased feeding also would not help to us. That the clouds have nonconstant inductivity on the volume, electrical distance between elements of the antenna will vary. Therefore, the antenna directional characteristic same will vary under the unknown law. Therefore in our case of disposition on Ai-Petri the simple single-element antennas could work only.