From: qrp.gaijin@... Sent: Nov 5, 2013 9:34 AM To: loopantennas@... Subject: RE: Re: [loopantennas] 1.5-volt active loop antenna?
---In loopantennas@..., <christrask@...> wrote:
I have a schematic in mind if you're interested.
Thanks for the suggestions. Yes, I would be interested in any further schematic details you might provide, even if only tentative.
I just added the file "Active Loop Amplifier for 1p5V Operation.pdf" to the group files section. I should point out that for loop antennas the input impedance of the amplifier should be very low, so I will later add a schematic for a more suitable design later.
As an experiment I tried running the antenna off of about 2.4 volts, with no circuit changes. The loop element is about 2.5 meters of copper foil shaped into a diamond. Though signal levels were lower than normal, the antenna did work reasonably well indoors for SWBC listening, and I could hear a few hams on 40m as well. I noticed no IMD, probably because the concrete building kept signal levels low enough to avoid problems.
Good IMD performance at low voltages will be tricky. You'll notice in the schematic that the biasing is accomplished by way of current mirrors so as to maximise the emitter-collector voltage.
