Home made magnetic loop antenna
by George Hardesty
(Carrier Mills , Il , USA)
I have seen many adds for commercial magnetic loop antennas 300 dollars and up in price. I didn't want to spend that much money on an antenna that might just end up being advertising hype!
But looking at them I thought ... if they work, there must be something in the circuity I didn't understand. That put me off for years.
I finally ran into the right guy. I told him my quandary. He (K9GHD) said he had home-brewed several on the spot when he was on the road and staying in motels. He talked me through one with a demo.
The next night, I built my first one with a 26 inch aluminum bicycle wheel and a dollar capacitor from an old receiver. Total cost: ONE dollar!
My magnetic loop antenna tuned from 10 meters to 20 meters inclusive. Yes, CB also!
While it was sitting on my bed and I was running through the tuning to see how far it would go, I'd send a question mark and call sign on a frequency. On key up on ten meters, a Hawaiian ham came back to me on ten meters with me using 25 watts!
My QTH was Southern Illinois! Moral of story is: if you see something that "trips your trigger", explore the web all about it. My one dollar antenna is the equal of MFJ's any day!
P.S. Pictures at a later time.
VE2DPE's Editorial Comment:
The magnetic loop antenna is indeed a fascinating antenna. In spite of its high Q and sharp tuning characteristics, this type of antenna can perform quite well indoors. One of its main advantages is that a loop antenna is notoriously capable of some directivity.
But, fair warning. Among its drawbacks are the high voltages present when transmitting, even at QRP levels! One must be extra careful to prevent anyone - or anything - from touching the antenna. The mag loop antenna is not the kind of antenna you want to use, on vacation, in a motel room or inside a trailer, where kids can burst in unannounced!
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