Perhaps the Best 75M Local & DX Antenna - Put up cheap!


Hi All,

The other night I was on the air with one of the NE AM guys who was saying
he didn't have much hope of getting lower angles for west coast on 75M 'cuz
he couldn't get his dipole higher than 70-80'. He was surprised to hear
otherwise.

This has been discussed here before, but worth repeating. The GOOD NEWS: A
pair of coax fed phased dipoles at only 50' or higher will work quite well
at lowering the take off angle, giving a front-back of 15db or more and 4dbd
(over a single dipole) of forward gain.

The reason it works so well is that it uses all driven elements. The low
parasitic Yagis or guys who use reflectors close to the ground are missing
out due to poor element coupling from ground effects.

Here's the easiest way to put up and employ two phased dipoles: Stretch a
strong rope or cable between two trees as high as possible with two inverted
vees attached to it and feedpoints separated by 60' or so. (like a Yagi)
Keep legs parallel to each other and broadside to your favorite direction
just like any Yagi. (broadside it NE/SW in New England) Feed both with equal
length coax that are BOTH run into the shack.

In the shack:
You now have two dipoles attached to two separate, equal length coaxes. For
high angle local work, just tie the two coax connectors together with a coax
'T' adapter and load into it. For a beam in one direction, add an extra 43'
of coax to the dipole nearest the direction you want to beam and tie the two
coaxes together and load into it. Switch the extra 43' coax length to the
other dipole to beam in the other direction. Don't worry about the slight
swr you see with the various configurations... the losses don't amount to
beans on 75M.

That's it! There's ways to add bells and whistles for instant switching and
lower SWR matching, but this simple set up will get the array on the air and
working well. You WILL be impressed how well an ALL DRIVEN array can work
when closer to the ground than the norm. (1/4 wavelength high)

Just ask W2INR about his version. Or Frank/GFZ. Or Dino/KNX. Or W1HI from
Rhode Island who runs pile-ups from Europe in the DX window with his. (His
is up about 65') And there's many others. Put this system up and you will
have the ultimate local cloud burner, and will be able to hear distant Amers
better when in the directional mode since the array will cancel out noise
off the back due to the f-b. Imagine being able to drop your atmospheric
noise down between 3-15db depending upon what weather you can null off the
back.

This array will give the average ham the chance to beam Europe for ssb Dxing
work in the window and also work the coast AMers. Local work is enhanced too
in the cloud burner mode.

I'd sure like to see a few more of these antennas go up. Compared to the
normal single inverted L's, horizontal Quads, dipoles, etc etc, this antenna
has an edge for whatever height or job you want to give it - and is not that
hard to put up for the average lot with reasonably tall trees.

For those of you with a single tower, (or TALL TREE) just hang a 40' boom at
the top using overhead trussing and guy this boom with the inverted vees.
Pull the legs out as far as practical. Of course, if you can use dipoles
instead of inv vees, you will see somewhat better performance in all areas.
Ask me for ideas about boom material if this "single support" aspect
interests you.

I seem to remember hearing about a few of these systems out west when
talking coast to coast on 75M. Anyone else have a version going?

73,
Tom, K1JJ