40 M antenna ideas

So I got a line on a military AB577/GRC 60 ft. rocket launcher type portable antenna tower. guy said I could have it just make an offer, was his dad's and been sitting on a shelf in the barn for 10 yrs. I said $200, and he said come get it.

soooo....I currently just have a horizontal dipole strung up on some old tent poles, about 12' in the air, 32' or so each side I am using.

what Should I do with this tower, use the same wire dipole but make it inverted Vee style, and if so, do I go as high as I can or keep it to 35' at the peak?

or is there some other kind of antenna I should make and stick up there as high as it will go? I don't have a rotator so I am thinking directional is out.

WWYD?

edit; I should add I have all the room in the world (out in the country, 21 acres, and an understanding wife), and already have a commercial 4 element folded dipole I got off a building I use for 2m, so I am interested in something better for 40m, since I can't seem to transmit at all on the dipole where it's at...

How about an end fed?

AB-577 Product Reviews

I'd start with an inverted vee and see how that plays. Should be a big improvement over your current antenna simply due to the height. From there you can experiment, the world is your oyster.

Let's start with your dipole. You mention 40m but you also mention 32" or so each side which would be short for the 34-35' needed for resonance. This might be a problem.

Next you indicate 12' elevation and not getting out. The reason is that twelve feet is less that 0.1 wavelength elevation. This is low. At this level the RF in the wire is reflected upward in a perfect circle. The usual broadside radiation characteristics we usually think about are not clearly defined until a dipole approaches ½ wavelength high (70 feet).

Here is a table of elevation effects on radiation pattern from 160 to 6 meter bands. Elev Effects on Rad Pattern

The upward radiation just goes up without with good sunspot activity. No down. Vertical Incident Skywave (NVIS) on 40m is extraordinarily rare now and for years to come. Short distance ground wave communication is a practical possibility.

With a single tower, the inverted “V” dipole is the usual configuration. If you can get your tower up to 50-60 feet, this antenna will come close to performing like a dipole on 40 meters.

Here is modeling information about what happens at ½ wl elevation when a dipole is bent into a “V” of various angles. Center-fed Horizontal V-dipole

40 meter

Go directional like two element cush craft beam or rotatable dipole

Well just got the mast but it's not what I thought. It's the gra4, 8 5 ft sections guy wire stakes hammer all pa led up. He let me have it for $100. Trying to set it up but not sure how far apart to put the stakes there are 5 alum ones and 4 large wooden ones. 4 tie plates, not sure how many sections go between them. Army manual I found online is a different setup (showed 3 plates and shorter sections) anyone know?

My wire is correct length I just guessed at 32 ft because I didn't remember it exactly but it is half wave 63' 1" for 7.1 MHz

With the 40 foot limit and your interest in distance communication a vertical radiator should be considered. There are two ways to go.
First, a quarterwave monopole with radials;
Second, a delta loop that does not need radials. This is set up like an inverted "V" only connected across the bottom and fed near one corner.

There is lots of information on verticals with radials. Less for delta loops. A good site about a vertically polarized 40 meter design is:
Ham Radio Site - [HOME].

Look under "My favorite antennas". The 40m Delta Mono-Loop.

I think I finally figured out how to set it up, apparently the went away from the 3ft. sections (nominal 2.5 ft.) and went to 5 ft. sections sometime later. For some reason I have extra plate and stake, but that may be for a long wire, since it has the halyard with it for hoisting up a wire. I assume the wooden stakes are for the ground plane.

anyway, I started to put it up before the tornado's hit Saturday but stopped so I didn't get any further with it. I did notice in the army manual they show dimensions for a delta loop. I may go that route and see how it does...