So if as Nigel Goodwin says scopes are not sensitive enough to show the waveform (not 100% accurate, I was able to view the carrier wave on a scope with a crystal radio, but I need shorter wave and farther transmitters), then Ronsimpson 2 antennas in parallel makes the most sense. But as I said, I was unable to get reduction of a distanced signal strength in neither Spectrum analyser nor Sdr, though theoretically as he mentioned, the strength should be 0 or twice as we move one antenna.
What am I doing wrong?