The Antenna of preference is the Military unit designated AN/GRA-4, which is a vertical antenna
            40 feet high with a provision for adding a whip at the top to make the overall length 55 feet. The
            manual for this antenna system is here. There are several other manuals available also drop a note
            via e-mail if you need them.

            I made a few modifications to the system, the top guys were replaced with wire in order to make
            a sloping capacitive hat for the setup. The ends of the hat are joined at the bottom and top to all
            four guy installations. I think a picture is needed to get a feel for what was done.

The AN/GRA-4 all packed up!



It contains all the guys and stakes and a
5 pound sledge hammer to set it up.
One man can erect it in about an hour.

            Well, after a few thoughts on the subject of Low Frequency antennas I decided to just put one up
            and try it out, and make changes as I go along. The AN/GRA-4 is part of a larger system known as
            the AN/GRA-50, which comes with dipole center insulator , and wire on spools, also a tape for
            measuring out the correct length for the dipole.

This link takes you to the Development Project
600 Meter Single turn Loop
with preamp for receive.

For a Tried and True Military type antenna might I suggest,
The AS-3577, it is a 600 ohm terminated dual Delta Loop.

Has an average height of 35 feet or so.

The manual is here, it is rated 2 - 30 Mhz, but I find
by removing the balun and adding a coupler, it
loads down at 500 Khz as well, with good current going to the antenna.

For omni-directional receive capabilities I also use the
AMRAD Probe antenna. It does a very good job
even considering the 200 ft. feed-line down
to where the receivers are in the shop!
The AMRAD article is here in PDF.

Southern Avionics makes a 90 foot, top loaded vertical antenna
AKA the Symmetrical "T" Antenna System
I decided to make a similar antenna to see what the
performance would be like as a 500 KC transmit antenna.

Here is their brochure for their antenna system.
and here is a photo of it as well




Here is my result after the trip to Home Depot
100 ft. stretched out in the hall.





The center and down lead junction





The three Top-Hat lines are joined at the center,
then all connected together
into one down lead.





Because of the height of the building I used for suspending the antenna,
The down-lead overall length is 130 Feet.
which goes to a base loading coil, Tapped.
Then to the transmitter.

The top-hat spreaders (3) are pre-cut 2 foot lengths.
and the leads are joined with these clamps.



The preliminary layout of the pieces and parts.









The end support/spreaders.




The center spreader has three holes to
accomodate the three downleads
as well as the horizontal runs.





And of course loads of wire, in this case
I got a single 500 Ft. spool of #14 stranded.





The ground radials are isolated from Earth
and consist of Cat-5 excess cable to make
this radial system. The stakes were bought at Home depot,
you will need 12 + 1 (13) for the center position.

NEVER throw anything away!