![]() ![]() ![]() I could pick up a 50 kW AM station from about 20 miles away reasonably well with a crystal radio and the right headphones. Being close to a powerful transmitter helps a lot.īack in grade school, I had a long line antenna out a window in my room to a shed in the back yard, maybe 60 feet long. Of course the available power in the air is important too. Most commercial AM, for example, are vertically polarized. One problem with the blimp dipole is that it would pick up horizontally polarized transmissions. There are other self-contained antennas that have other radiation patterns, but their shapes wouldn't be as compatible with the stucture of a blimp. It would pick up signals to the sides, but not directly in front or in back. The orientation of the blimp would be important. ![]() A dipole the full length of a blimp and hung below it might intercept enough RF power so that you can hear the demodulated signal with the right headphones. The reason most crystal radios work with a long line antenna and the other connection ground is because that's a good way to intercept reasonably high RF power, relatively speaking. Dipoles, folded dipoles, and loops are just three examples of such antennas. Many antenna types are self-contained, in that they don't require a ground or use ground as one of the two connections where the signal appears between. ![]()
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