From a long wire and a matching device, you can make a Fuchs antenna for short waves to conduct radio communications over very long distances
This antenna works well at frequencies of 3.5-12 MHz, the frequency is changed by a variable capacitor. To shift the operating frequencies, you need to rewind the transformer windings.
To make an antenna you will need a wire approximately 45 meters long, but you can use a wire of a different length. I live on the tenth floor. The wire goes down from my balcony and is attached to the road sign in the yard through an insulator. Of these 45 meters of wire, there are probably 5 or 7 meters maybe I cut off more as unnecessary. In general, the length should not be very precise. If you live on the first floor, take as much wire as you need to throw up a tree or onto some kind of support, but not less than 10 meters or maybe more, I did not conduct tests here. The main thing is that the wire does not go above or below the power line wires. Observe safety precautions. And it is advisable that the wire is not accessible to neighbors, they can cut it. To prevent this from happening, I made a type of protruding on the balcony there is a fishing rod 1.5 meters from the balcony. The neighbors below will not be able to reach the wire because of this, unless they try really hard.
I bought the wire at an electrician’s store. For low transmitter powers, the diameter of the wire can be 1.5 mm.
One wire can work well at any one frequency. In order for this wire to work at different frequencies, you need to make a matching device, which consists of a variable capacitor 12-495 pF and a transformer containing two windings. The transformer is wound on a plastic frame with a diameter of 20 mm. Winding L1 contains 20 turns of 0.7 mm wire, winding L2 is three turns of 0.7 mm wire wound on top of L1. By adjusting the position of L2, the best performance of the antenna is achieved. If you use the transmitter at a power of more than 10 W, the capacitor plates can break through from high-frequency voltage. To make the capacitor higher voltage, To do this, connect two sections of the capacitor in series, and the capacitance will change.
Tested the antenna with a radio station at different frequencies. 3.5-12 MHz work quite fine. The antenna requires a counterweight or ground. This could be a 2-3 meter long wire dropped on the floor, but if possible, ground to the central heating pipe or you can try to the ground pin of the outlet, if you have one.
I attached the antenna below to the road sign in the yard. No one has made any complaints yet, but it would be better if the wire were smaller in diameter and less noticeable.
