Delta or Dipole?

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?

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.

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.

Attachment 12393

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

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Originally Posted by KJ3N

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

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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.

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

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

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.

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

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Originally Posted by WØTKX

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

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

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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.

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.

Quote:

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Originally Posted by WØTKX

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

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

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That loop is 30m high. I'd try modelling it at 4m above ground.

Yes, that link was not perfect, but it shows the feed-point vs polarization issue.

Picky, picky, picky. :roll:

Don't have modeling software here at work, but folks I know who use low mounted delta loops on 40 and 80 move the feed points around based on their installations and the distortions to the equilateral triangle. It ain't gonna be ideal.

That being said, I think Ron will have better luck with some sort of a vertically oriented vertically polarized loop for his current situation, right? So there we go. Unless he can do a separate RX and TX antenna setup, typically a lot better for top-band.

Right Jim?

But............I was always told size doesn't matter. Who Gnu?

since you already got a HF2V (and if it works well) why not just get the 160m add on for it?

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Originally Posted by W2IBC

since you already got a HF2V (and if it works well) why not just get the 160m add on for it?

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I have the TBR-160.

It does not work well the the Butternuts.

First, it drastically affects the bandwidth on 80 & 40 meters. The nominal 2:1 bandwidth on 40 is over 200 kHz; it's about 100 kHz with the TBR coil. The nominal 2:1 bandwidth on 80 is about 80 kHz, with the coil, about 50 kHz.

Second, the usable bandwidth on 160 is about 20 kHz. Some don't get more than about 16 kHz.

Third, to get even that much performance, you have to lay down a sh... lot of radials. At least 24 to 32.

Fourth, if you plan on running power, it's well known that as the coil assembly heats up, the frequency shifts. So you can very quickly go from a reasonable SWR to an unreasonable one.

And finally... look, the HF2V is a full 1/4 wave on 40 (the HF6 is electrically a 1/4 wave, although physically a little shorter), and 1/8 wave on 80/75. But it's only a 1/16 wave on 160. That's just plain not much of an antenna on the band.

The TBR-160 is just plain not worth it. The best that can be said about it is that if you have no other choice, it will (probably) get you (just) on the band. If I could only have one antenna, I'd put it back on. Since I have other options, though... nah.

Update...

Current plan is to go with the Delta Loop. I simply have to decide how (mechanically) to hang it. One thought would be to simply use the top of the mast to support it; another would be to use the two legs as guy wires (electrically isolated from the mast, and tied together to form the loop). Right now, I'm favoring the first option for the sake of simplicity.

Saturday afternoon, after the ladies head down to DC for the rest of the weekend, I have a couple of "prep" things to do. One is to take down the HF2V. Then I'll assemble the mast into two 20 foot sections (using stainless steel bolts, of course) in the garage. The "tricky" part is going to be what I'm doing at the base of the mast. Current thought is to cut down a 4 foot fiberglass mast to act as an insulator (ie, be the feed point for the Inverted L part of this project). What I'm also considering is to cut down one of the 4 foot aluminum masts... use about 2 feet of it in the ground for mechanical support. This would let me put the "ring" that will hold the guy wires and the top of the Delta at the very top of the mast, and then use the remaining section of the cut mast above that. That extra 2 feet or so would be the separation between the L's horizontal wire and the top of the Delta. Not an ideal spacing... but I have to work with what I have.

Sunday morning, I take the pre-assembled mast sections out into the back yard, combine them into the net mast, and get the wire for the Delta ready, along with any guys.

Then, Sunday afternoon, when W3WH & K3VX come over, we re-attach the L horizontal wire (or throw up a new one), raise the mast, bolt it in place, and spread out the Delta.

That's the plan. Let's see what really happens.

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Originally Posted by W3WN

Update...

Current plan is to go with the Delta Loop. I simply have to decide how (mechanically) to hang it. One thought would be to simply use the top of the mast to support it; another would be to use the two legs as guy wires (electrically isolated from the mast, and tied together to form the loop). Right now, I'm favoring the first option for the sake of simplicity.

Saturday afternoon, after the ladies head down to DC for the rest of the weekend, I have a couple of "prep" things to do. One is to take down the HF2V. Then I'll assemble the mast into two 20 foot sections (using stainless steel bolts, of course) in the garage. The "tricky" part is going to be what I'm doing at the base of the mast. Current thought is to cut down a 4 foot fiberglass mast to act as an insulator (ie, be the feed point for the Inverted L part of this project). What I'm also considering is to cut down one of the 4 foot aluminum masts... use about 2 feet of it in the ground for mechanical support. This would let me put the "ring" that will hold the guy wires and the top of the Delta at the very top of the mast, and then use the remaining section of the cut mast above that. That extra 2 feet or so would be the separation between the L's horizontal wire and the top of the Delta. Not an ideal spacing... but I have to work with what I have.

Sunday morning, I take the pre-assembled mast sections out into the back yard, combine them into the net mast, and get the wire for the Delta ready, along with any guys.

Then, Sunday afternoon, when W3WH & K3VX come over, we re-attach the L horizontal wire (or throw up a new one), raise the mast, bolt it in place, and spread out the Delta.

That's the plan. Let's see what really happens.

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Glad to see the antenna will be up on Sunday; your neighbors tree trimmer is due back on Monday.

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Originally Posted by K7SGJ

Glad to see the antenna will be up on Sunday; your neighbors tree trimmer is due back on Monday.

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Good. He owes my neighbor $50 to cover the cost of replacement aluminum on the HF2V. :twisted:

explains a lot actually on the bnut &160 guess that is a route I won't be taking in the future.

All antenna's we set up are compromises.
Even my inverted L 77 feet high and 77 feet to the side with 3000 feeet of radials and 0.003 Ohm resistance fed at the base with the MFJ 998 is a compromise, full bandwidth on 180 to 20 meters .
The Frizel OCF Windom with added coil and 30 feet of wire works on 160 centered at 1.850.
For 17 -10 there is another vertical on the roof, so i can pick horizontal/vertical antenna on all bands.
Homebrew receive loop in the back of the yard adds receive choice extra so for receiving i have for each band 3 different antenna's to chose from.

Having an Windom at 45 feet above ground doesn't really work on 160, bar as receive antenna, the L does the main work there.
For 80 the OCF works fine in Europe, the Inverted L does much better long distance for the vertical radiation, same as 40.
20 is a toss up, the L starts to open up and depending on where the lobes are it works or not.
The Windom does fine on the higher bands, the vertical there adds DX better as the windom.
For 50 MHz there is the 5 element beam... ;)

Closed loops i dabbled with on Jota/Joti's 160 meter horizontal polarised and 30 feet up, quiet in listening and working quite well multiband.
You do need a lot of space though.... a Delta loop vertically will also be quiet and add DX multiband.
Good luck with your set up ;)

Well, we got the loop up this morning.

W3WH came over around 10. I already had the mast assembled.

It wasn't easy.

The small fiberglass section cracked; Bill inadvertently put more stress on it during our first two attempts to raise it than I expected, and it cracked. I was able to remove it, but that shortened the mast, and prevents it's use, for now, as a vertical.

Took us 5 tries to pull it vertical. I'd misjudged the mass of the mast. I was used to maneuvering the HF2 and HF6, and this was much more massive. We should have had 2 more guys helping us.

But, it's up, and the delta loop is in place.

It loads on 160, but I think it's too short. Time will tell; we have some thunderstorms this evening, so I'm not testing anything until tomorrow night at the earliest. I could hear W1AW/4 AL, but kinda weak. But that could be conditions.

.


For what it's worth, my 80 meter turnstile is actually
2 inverted vee dipoles at right azimuth angles.

It's apex is up 48 feet, supported by 13 feet of 2-inch PVC
atop a 36-foot steel tower. Ends droop to about 27 feet.



Tied together, the 4-wire feedline forms a cage umbrella vertical
fed against radials and powerline neutral--excellent low-band DX.

Do you work 160 CW? We could try a sked (once the QRN subsides).