Thank you all,
I can do understand Russian very little too:-( The problem is I am new to
all this technical radio stuff. I am an ordinary SWL for two years from LY
country:-), I started interesting in ham bands so I bought this radio to
explore them. Well as for AM listening the receiver do quite well, but for
ham band is worse. I decided to experiment with antenna to expand my
listening capabilities. So I came up to impedance question. I thought it is
very important. After your replies I try to do some random wire antenna test
first:-).

Thanks for your replies.
Your sincerely,
Edgar
73!