The QRPer Board

Hi, I have a noob question about mag loop antennas.
I inherited a coil of 3/8-inch OD copper tubing.
I would like to build a 20 M magnetic loop antenna for portable operation.

Question - If I'm happy with a narrow band of frequencies (e.g. FT8), can I build one without a tuning capacitor?

Follow up question - How sensitive is the loop to the surroundings. I'm in North Dakota, so I envision putting a tripod with loop a reasonable distance from my car and it will almost always be flat without trees.

Thanks,
Ted, Wo0R

The short answer is no - a magloop is essentially a large LC circuit, so it needs "C". Having said that, you could use a fixed-value capacitor that will resonate the loop on 14.074, but I'm not sure how sensitive the loop would be from installation to installation. I have a few small vertical antennas that tune up well in my yard, but generally fail to tune when I use them somewhere else.

K1FM has a small magloop design that uses fairly common variable capacitor that you might find useful:
https://k1fm.us/2015/07/k1fm-mini-magnetic-loop-2-0/

GL es 73,
Mike, KL7MJ

Thanks!

check this loop for the 20m band

http://sm0vpo.altervista.org/antennas/20m_ant_00.htm



HTH

That's a cool antenna! I've been playing with a Gawant and an L match recently, but I'm going to try this (and the 80m version too)!
Thanks for sharing!

73,
Mike, KL7MJ