Construction and Description of a 160M loop antenna
The Super Hoosier DynaLoop consists of four 35ft (average) utility poles buried an average of 5ft, 125ft LMR-400 from R&L Electronics, a 5KW-rated 4-1 balun, rope and marine-grade hardware (mostly from EBay) and a 20ft length of 300ohm ladder line.. The closest pole is nearly 100ft away from the shack. The poles are 140ft apart. The antenna is far away from any power lines, and occupies the back 1.5 acres of my property. Note that one pole was a bit short, so had to be built up with a treated 2X4.
The basic plans for this antenna has been copied and posted in many places on the Internet, but here is one reference.
The math-derived 558ft proved to be way too long; the actual length was something close to 510' (in all my years of building wire antennas, I've never found 1-1 correlation between theory and practice.)
There are clearly a complex multitude of harmonic resonances in this antenna with the balun. Automatic antenna tuners just will not work reliably. I attempted to hook up an MFJ remote tuner on the pole, but gave up: it was too easily confused. I currently use a vintage, beefy Heathkit SA-2060A on the shack side, knowing that I'm heating up over 100 foot of coax.
The performance is overall very good, and noise is quite low. The arrangement works well with the excellent Acom 1010 amplifier at 750W, but I'm reluctant to push it to legal limit with my manly Heathkit HL-2200 (despite the theory.) I'm now able to work most AM traffic in Wisconsin and Michigan, which was nearly impossible on my end-feds.
You will need a competent contractor, four utility poles and a skid loader with an auger. It's tricky to manipulate the long, heavy poles with a such a small skid loader, but it can be done. Bring chains and a few extra pairs of hands for help.
Use the best stainless hardware and rope you can find, and change out the rope every couple of years, because you don't want to have to climb the poles. Total cost for me was around $1200, but I was lucky; it isn't always easy to find resources like this. But with a little bit of maintenance, I should never have to worry about competent antenna options on the lower frequencies again.