- Joined Jun 1, 2016
misterBill2, you very polite-)The frequency ratio for such a wide band of frequencies is large, while the capacitance ratio for most variable capacitors in real circuits is much smaller. So if you want a resonant antenna, which provides greater sensitivity, a switching arrangement would be required. But most such antennas only have one turn of wire, centered inside the shielding tube by means of beads of a suitable diameter to slide freely while still holding the wire centered. This is done to reduce the capacitance to the tube, which would reduce the tuning range as well as the sensitivity. For a detailed circuit of such antennas visit the "schematics for free" website, which has all kinds of circuits including a number of amplified loop antennas.
I don't provide a link, you will need to visit the site and use the directory tree to locate the circuit drawing. That does require a bit of focus and a minute or two of clicking, but the site is interesting enough that the search can be fun.
thxs again, i will try there on sit you said-)