I'll be back with a correction. Because of a soldering mistake the antenna actually was not connected to the receiver. I put an photo to explain what I did wrong. There are an place where can solder antenna wire. But this place need to be connected with coil pin nearby. Now with right soldering i have over 20m range with single wire antenna, length aprox. 34 cm (half wave length)
Because i discover this mistake quite late i don't have time to repeat test with dipol antenna, but i will do that when will have more time, just as curiosity.
I apologize for the confusion that I created it!
