Delta or Dipole?

[W3WN]

OK, so circumstances have arisen that will leave me home alone (well, except for the puppy) for the bulk of the weekend.

This will give me the opportunity to drop my HF2V and replace it with a 44 foot aluminum mast. Current plan is to make this the vertical portion of my rebuilt inverted "L".

That said, I've had some friends urge me to take further advantage and add another antenna to the mast.

I was originally thinking of doing a Delta Loop, with the apex at or near the top of the mast (some mechanical issues involved there), and fed at the center of the bottom wire. Initially I'd feed this with a 4:1 balun I have, possibly with a little ladder line from the balun to the feed point on the antenna.

However, it's been recently suggested that I go instead with a simple Inverted V, instead of a Delta. Obviously, this would be fed at the apex, again most likely with ladder line, keeping the balun down near the base. [ Why keep it at the base? Because eventually, the balun will be replaced with an auto tuner, once some other issues (ie power and mounting) are resolved. ] And I can always convert this into a Delta loop later, if I'd like.

I'll try and work up a sketch or two later to give you all a visual idea of what I have in mind.

So, what do you think... which one will be more likely to be effective, especially on 160? A Delta Loop, or an Inverted V?

[WØTKX]

What are you wanting to "cover" on 160?
DX, or local/stateside? Other bands?

The delta loop has the advantage for DX at modest antenna height. The inverted vee would be a better multi-band antenna, if that matters.

[W3WN]

I'm more interested in DX on 160 than domestic. (I only need 2 states to complete 160 WAS, Alaska & Nevada). I'm not too concerned about multi-band, since I'll still have the HF6V in place; that does very well on 80 - 10.

The below diagram (not to scale) gives you an idea of what I'm looking at. The chain link fence is about 4 feet high, which I don't think I put on the diagram.

Possible Antenna.jpg

[KJ3N]

I'm confused. Is the inverted vee / delta loop full size on 160?

[W3WN]

I'm confused. Is the inverted vee / delta loop full size on 160?

Nope.

Figuring that the apex of the antenna, either way, will be about 40 feet above the fence... as an inverted V, each leg is about 57 feet. That's not quite a half wave on 80 (~132 feet), let alone 160.

If it's a Delta loop, add about 80 feet across. That's close to a full wave on 80... but only close to a half wave on 160.

Best that I can do right now with the space and materials available.

[WØTKX]

For DX, you're gonna want to put the feed-point on a bottom corner...

http://www.wf7t.net/archives/194

[W3WN]

Oh, I should add that the above dimensions assumed that the two legs had a 45 degree angle from the apex.

Now, make it a wider angle... say, 60 degrees... then the sides go to 80 feet, and the base goes to about 139 1/2 feet. So that way, it's a LOT closer to a full wavelength on 160.

A lot will depend on exactly how we hang it, when all is said & done.

[WØTKX]

Making it big is most important. You can move the feed point to optimize the pattern with the geometry you end up with.

[W3WN]

For DX, you're gonna want to put the feed-point on a bottom corner...

http://www.wf7t.net/archives/194

Hmmm. Interesting.

I like his reasoning. Thanks.

As a practical matter... this actually simplifies a few things. I can simply "loop" the wire at the apex, and simply insulate the two ends at one corner or another (from each other, that is) and feed it there.

And if I ever want to switch polarization, it's simple enough to move the feed point.

[KJ3N]

Well, playing around with EZNEC 5 (which I only have a basic understanding of), I don't see the point in having the inverted vee. The pattern is still pretty much NVIS on 160m. Having the delta loop fed at the bottom doesn't alter that pattern much, either.

An interesting thing does happen if you have the delta loop fed at the top, however. It gives a shallow figure 8 pattern with gain in line with the direction of the bottom wire. The TOA isn't too shabby, either. There's also nulls perpendicular to the loop, about 9db down.

In any case, I'd be more concerned about the amount of detuning and pattern skewing of either antenna, given the close proximity.