Ham Radio Forum

Within the last several years I ran across an article describing design of single loop transmitting antennas built from copper water pipe of 1/2, 3/4, and larger diameters but I cannot find it now. This discussion included formulas for the inductance of round, square, octagonal, etc shaped loops.

Can someone direct me to the reference for this article. It is likely QST or QEX and published after year 2000.

Many thanks

Jess, w4pqk

Right here on Smeter there is a free design program where you enter all the variables. I ran it and it gives all the details for consideration. Do web search for construction. I am trying to design an 80 meter mag loop.

Trickiest part appears to be the tuning cap, relating to voltage and adjustment

ARRL antenna handbook covers the subject too.

Thanks for the info.

Can you give me the handbook reference where they are discussed please? In the discussion I remember there were a number of designs worked out for various bands and for various diameters of copper tubing, I believe.

As far as the capacitor, the most important characteristic is that there be no mechanical connections such as with the common variable capacitor. A butterfly type capacitor (two separate stators and a single rotor) is good assuming adequate voltage rating.

I've considered using two sheets of circuit board for the capacitor, suitably separated, with copper braid making the connections to the copper loop with some provision for varying the spacing.

Good luck on making the 80 meter loop.

Thanks, Jess, w4pqk

Post subject: Inductance formula for single turn loops various shapes
Posted: Wed Dec 28, 2005 11:03 pm


Well, here it is nearly a year later. I have since found my answer,..., and lost it again. But I put it in a folder and it can be found at:

ARRL Handbook, 1991, 16th Ed, Chap 5, pg 5-4
Triangle, Square, Hexagon, Octagon shaped loops.

But, I can't find the 1991 Handbook, if I ever had one.

Therefore, I posted this as another reference to where I found the information in case I find the 1991 Handbook.

Jess