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eHam Forums => Antennas and Towers and more => Topic started by: KF7DS on November 16, 2012, 07:41:18 AM



Title: Dipole vs. Vertical
Post by: KF7DS on November 16, 2012, 07:41:18 AM
Now that the leaves are gone, I have a chance to thin out the trees in my backyard and create clear areas to string a few wire antennas. The first one will be run n-s (with a tilt more north), and the second one (if I can get to it this year) will be e-w.

With the n-s wire, I will use a DXCC Alpha Delta. I can use a 45' mast for the center feed, and get the ends up high also....

I work 10-40m, mostly CW at 100W. Occasionally visit 80m. Interest is both US and DX. Currently have a 6BTV...I cannot accommodate the DXCC and the 6BTV, so the choice is to either string the DXCC n-s on a 45' mast, or go with the 6BTV (which works well...have AU, NZ, FR, PUR, RUS, and 43 states in one year of casual operating)...can't have both.

Feedback welcome.

Don KF7DS


Title: RE: Dipole vs. Vertical
Post by: WA2TPU on November 16, 2012, 08:15:37 AM
Hi Frank,
   Ever consider a 40 meter vertically polarized Delta loop??
Best regards and many 72/73.
Don sr. --WA2TPU --


Title: RE: Dipole vs. Vertical
Post by: WA2TPU on November 16, 2012, 08:17:21 AM
I meant Hi Don. Sorry abt that.
Best 72/73.
Regards,
  Don sr. --WA2TPU --


Title: RE: Dipole vs. Vertical
Post by: KH6AQ on November 16, 2012, 08:34:09 AM
The DXCC dipoles mounted as described will outperform the vertical. This is not because the vertical is inherently inferior but because of far-field ground losses attenuating vertically polarized RF much more than horizontally polarized RF.


Title: RE: Dipole vs. Vertical
Post by: KC9Q on November 16, 2012, 09:26:51 AM
Interestingly, there is an article on Page 45 in the December 2012 QST that discusses this very topic:  "Vertical or Horizontal HF Antennas - What's Best for You".


Title: RE: Dipole vs. Vertical
Post by: KB5UBI on November 16, 2012, 09:59:17 AM
Not again. Vertical V. Horizontal. I know there is a lot of anti-vertical bias out there, but a properly installed vertical works well. Multiple antenna designs are the answer. I have a multi band vertical, two horizontal doublets and a vertical polarized delta loop. Except for the Butternut vertical, less than a 100 dollars invested in the other three antennas. I choose the one that works best for the condition. I would have to say, the vertical is my default go-to antenna, followed by the delta loop.


Title: RE: Dipole vs. Vertical
Post by: KF7DS on November 16, 2012, 11:02:58 AM
The DXCC dipoles mounted as described will outperform the vertical. This is not because the vertical is inherently inferior but because of far-field ground losses attenuating vertically polarized RF much more than horizontally polarized RF.

David:

That is what I was thinking. I am not dissing the 6BTV, it serves me well. But, in researching the possibility of a small beam, I kept coming back to the issue of height. I knew I could not get a small tower in the backyard (would not fit, would annoy neighhbors, the usual...) and then began to think about wires...I CAN get those up high

The problem is, the only area I have to put up a 45' mast is where the 6BTV is now located...so, it is one or the other hence the importance of my question for the n-s wire.

In thinking about this, this is not the case with the e-w dipole I plan to install (for n-s propagation)- that portion of the slope has plenty of opportunities for 3 points to hang from without a mast..maybe I should install that first and use it AND the 6BTV for a while and see how that goes.

Another question....the antennas will be in the clear...no closer than 8'-10' from any branch...but, many of the trees are deciduous, so the leaf canopy will come back in the Spring...it is not 100% cover, of course, but a lot all the same (this is Portland)...how will that impact the SWR, if any?

I really appreciate all of the feedback, even if the questions have been asked before.

Cordially,
Don KF7DS


Title: RE: Dipole vs. Vertical
Post by: STAYVERTICAL on November 16, 2012, 12:05:33 PM
Not again. Vertical V. Horizontal. I know there is a lot of anti-vertical bias out there, but a properly installed vertical works well. Multiple antenna designs are the answer. I have a multi band vertical, two horizontal doublets and a vertical polarized delta loop. Except for the Butternut vertical, less than a 100 dollars invested in the other three antennas. I choose the one that works best for the condition. I would have to say, the vertical is my default go-to antenna, followed by the delta loop.

Here we go again - let slip the dogs of war!

My advice:

1. Read some good antenna books - the ARRL handbook is full of good information.
2. Build/hoist them and try them - your location, like you, is unique - results will vary with location.
3. Throw away your preconceived ideas, and most of the replies you will get here (including mine).

There is no mystery to antenna performance - it is all known mathematically and can be modeled fairly accurately in free programs such as 4NEC2.
What is not modeled is what your local conditions are like - is that high voltage tower in the model?
Also, if you are in an urban environment and your neighbor has just wheeled in that new 100 inch plasma, how will that affect reception?

Part of the problem for antenna discussions is that they become hobby horse rocking contests.
The delta loop/dipole/vertical/beam guys all have their cans to kick noisily down the road - and you can't hear yourself think in the racket.

Do some reading - there is no magic antenna which does it all, but there is one which does what you want.

Good luck,

73 - Rob


Title: RE: Dipole vs. Vertical
Post by: KH6AQ on November 16, 2012, 02:32:17 PM
The question of tree attenuation comes up from time to time. I have found articles on HF attenuation of jungles and VHF attenuation of trees. But nothing that quantifies your installation. It seems to be agreed that trees are worse for vertical than horizontal antennas because a tree is a lossy vertical. If that is so you may have less attenuation with dipoles.


Title: RE: Dipole vs. Vertical
Post by: KB5UBI on November 16, 2012, 03:00:29 PM
Stayvertical and myself are usually on the same page but I say Do more building and less reading. You may be surprised to find that personal bias has contaminated some theories. Stop relying so much on Eznec style programs in the living room, go out in the yard and try building some antennas by the basic rules.

Verticals can work very well or they can be dummy loads depending on installation and nature. My suggestion is to build both.

S-Meters don't lie, signal reports; maybe.  


Title: RE: Dipole vs. Vertical
Post by: W2WDX on November 16, 2012, 03:06:05 PM
The most important thing I feel is the interaction of ground. A horizontal wire, if to low in regards to wavelength, is less efficient due to ground loss then one up high and in the clear. Vertical always perform better with massive radial systems, the more the better.

Putting up the antenna correct for the locale is also important. For example, if you have good soil conditions and a very large ground radial systems, a vertical will perform better for low angle DX work than a low hanging horizontal. In the same situation, the horizontal antenna might do much better closer in (NVIS). This example demonstrates the advantages of multiple antenna types being better than just "one antenna does all" type thinking.

Most opinions, especially the bad ones, of which type is "better" is more a factor of not giving one type or the other the right conditions for its type. Drawing conclusions from erroneous assumptions. A poorly tuned multi-band horizontal wire at 35' being tuned with an auto-tuner through cheap coax for instance, making a person think horizontal wire antennas are bad. Or someone hanging G5RV at 25' above the ground with most of tuning stub section of it near the ground, or worse yet piled in a heap (I have seen this). Or someone just sticking a Hustler on a pole in their back yard and using the auto-tuner in the radio and maybe just tying the base of the antenna to a 50' section of chain link fence in a locale with poor soil conductivity being the factor in saying verticals are a waste of time.

I've had a 160' doublet fed with ladderline at 90' high (no balun, just a Johnson Matchbox and the correct length of ladderline) and a 43' high vertical properly tuned with 40 tuned radials evenly spaced, and both worked amazingly well. They both performed extremely well because I gave each type what it needed. And chose the type that worked best for the locale at the time. I used the vertical when I didn't have a way to get a horizontal up high enough, but had the real estate to lay out 40 evenly spaced radials. I used the doublet when I was at a location where I could put it up flat-top at 90' above the surrounding terrain, getting it far enough away from ground losses as to be effective.

John, W2WDX


Title: RE: Dipole vs. Vertical
Post by: KB5UBI on November 16, 2012, 04:09:23 PM
"Putting up the antenna correct for the locale is also important. For example, if you have good soil conditions and a very large ground radial systems, a vertical will perform better for low angle DX work than a low hanging horizontal. In the same situation, the horizontal antenna might do much better closer in (NVIS). This example demonstrates the advantages of multiple antenna types being better than just "one antenna does all" type thinking."

Sounds like you agree somewhat with my findings. When I report my vertical works better DX than either of my gain doublets in two out of three QSOs, it starts a fire storm of critique. Maybe in the two dimensional Eznec world, the horizontal dipole out performs the vertical but in the real world at my QTH, my Butternut vertical is my "go to" antenna, most of the time. It is what it is.


Title: RE: Dipole vs. Vertical
Post by: KF7DS on November 16, 2012, 09:51:21 PM
All

Thanks for the feedback and encouragement. I am be setting things up for ease of maintenance and experimenting.

Should be fun.

Anyone use remote switch boxes?

Don KF7DS


Title: RE: Dipole vs. Vertical
Post by: STAYVERTICAL on November 16, 2012, 10:45:59 PM
"Putting up the antenna correct for the locale is also important. For example, if you have good soil conditions and a very large ground radial systems, a vertical will perform better for low angle DX work than a low hanging horizontal. In the same situation, the horizontal antenna might do much better closer in (NVIS). This example demonstrates the advantages of multiple antenna types being better than just "one antenna does all" type thinking."

Sounds like you agree somewhat with my findings. When I report my vertical works better DX than either of my gain doublets in two out of three QSOs, it starts a fire storm of critique. Maybe in the two dimensional Eznec world, the horizontal dipole out performs the vertical but in the real world at my QTH, my Butternut vertical is my "go to" antenna, most of the time. It is what it is.

I agree with KB5UBI.
At my location, the neighbors think I have antenna OCD with my switching between using dipoles and verticals.
After all my experiments, the results for my location and situation are clear and unambiguous.
The maximum I can get a dipole up is 30 feet and I use a number of elevated radials with my vertical with remote atu at the base.

The vertical is hopeless on local contacts, but leaves the dipole in the dust on DX just about every time.
On the vertical signal strengths are normally better by several S points on DX, but the QSB is more severe, and conditions more variable.
The dipole is usually less prone to QSB, and if conditions are good, will give a more stable contact.
The difference is probably entirely due to angle of radiation, with the low angle vertical winning every time.
Less skips, less loss - it's as simple as that.
Low angle radiation, large skip zone, more qsb as the ionosphere changes height.

So my OCD is over, and the lesson learned:
For DX - the vertical, for locals the dipole.

As others have said, you pick the antenna for your operating style, and acknowledge its nature with expected results.
DX is my passion, so I choose the vertical, but local nets and operation are often marginal.

In any case, its all theory until you hoist it up and see how it works.

Have fun,

73 - Rob


Title: RE: Dipole vs. Vertical
Post by: N0NCO on November 26, 2012, 10:22:00 AM
All antennas are compromises. As many have noted - there is no single antenna that is best for all locales, band conditions, and operating styles. However - if you only have room for one HF antenna & don't mind putting down a good low-impedance radial field, and if you have average or better ground conductivity out to 100 WL, and want to work the most directions with a low-angle signal, but still have enough high-angle radiation on the low bands for NVIS - a remotely-tuned inverted-L is a good choice. Note that there are a lot of 'ifs'. That's simply the way it is with HF antennas. Of course, the compromise for all of that horizontal coverage & high-angle NVIS is lower overall gain than say, a high-mounted remotely-tuned doublet or horizontal loop. However, gain alone is often less important than putting your signal where there is a high likelihood of it being received. And that is where a properly-designed, remote-tuned, multi-band inverted-L shines. See L. B. Cebik's excellent info on antennas for details:

http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf

http://www.antennex.com/Sshack/books.htm


Title: RE: Dipole vs. Vertical
Post by: STAYVERTICAL on November 26, 2012, 01:02:27 PM
All antennas are compromises. As many have noted - there is no single antenna that is best for all locales, band conditions, and operating styles. However - if you only have room for one HF antenna & don't mind putting down a good low-impedance radial field, and if you have average or better ground conductivity out to 100 WL, and want to work the most directions with a low-angle signal, but still have enough high-angle radiation on the low bands for NVIS - a remotely-tuned inverted-L is a good choice. Note that there are a lot of 'ifs'. That's simply the way it is with HF antennas. Of course, the compromise for all of that horizontal coverage & high-angle NVIS is lower overall gain than say, a high-mounted remotely-tuned doublet or horizontal loop. However, gain alone is often less important than putting your signal where there is a high likelihood of it being received. And that is where a properly-designed, remote-tuned, multi-band inverted-L shines. See L. B. Cebik's excellent info on antennas for details:

http://www.users.on.net/~bcr/files/backyard%20wire%20antennaes.pdf

http://www.antennex.com/Sshack/books.htm

I agree with you there.

One of the best multi-purpose/multi-band antennas I have ever used was the old style single wire fed windom.
When paired with one or more counterpoise wires (only a few feet above ground), it performs well on both DX and local contacts.
I guess it is really a massively top loaded vertical which goes dipole mode at certain frequencies, but it is certainly a good overall performer.
The inverted L you describe seems like a variant of this, so I am not surprised it is a performer as well.

Because of the long top section you don't get the overhead null of a standalone vertical so locals also get a chance.
As you said, the secret is the remote atu at the base of the vertical section.
Where the windom is perverted these days is in making it into some sort of g5rv or OCF dipole, by feeding it with coax right to the horizontal wire.
In that configuration you don't get the benefit of the vertical wire section, unless you have common mode currents, which is undesirable anyway.

So a classic single wire fed windom (or an inverted L), with a remote ATU, will give you dx and local contacts.
Although I use a vertical for DX personally (QTH restrictions), my experiments with the classic windom left me very impressed with its good overall performance.

If there is one thing I can recommend to antenna restricted or experimentally minded folks, it is get yourself a remote antenna tuner.
Your universe will expand enormously, and your frustration level will drop exponentially.
Much of the average hams time is spent trying to match an antenna's impedance to 50 ohm feedline, rather than experiment with antenna's.
With a remote ATU you just press a button and the matching is done.
Then you can concentrate on seeing how efficient it is and what its pattern looks like.

Another simple but extremely useful accessory for antenna experimenters is a field strength meter.
It does not have to be expensive - you can use two 1N34 diodes one capacitor, one resistor,  and a digital volt meter if you wish.
Alternatively, many of the cheap SWR meters have a FS (field strength) facility built in where you attach a whip or wire loop.
(Obviously it is taken out of line in field strength measuring mode).
This will save you having to build anything - and they abound at flea markets for a few dollars.

Amazingly, these cheap meters work up to at least 2 metres (maybe more but I have not tried that).
Many suggest using a whip, but I have found a loop of wire around 1 foot diameter is more stable in pickup mode.
Just take it from the FS terminal to the case of the SWR meter.

Rather than obsess about swr and wonder how the antenna is getting out - use your simple field strength meter to see the effect of any changes.
Now, the antenna pattern is 3 dimensional, and not many of us have pixie wings to fly around the antenna with a field strength meter.
But you can at least measure the low angle radiation strength and see what effect your changes make.

One thing to keep in mind when doing antenna measurements is the difference between near and far field radiation.
Basically in the near field (around one wavelength from the antenna) the electric and magnetic fields are still organising themselves into an electromagnetic wave.
They exist as separate entities and interact with each other to produce the travelling, never to return electromagnetic wave of the far field.
There is a complex dance in the near field region, with energy being provided and returned, so impedance of the antenna is influenced by what you do within the near field region.

This is why adjusting a beam antenna's parasitic elements influences impedance at the drive point - they are in the near field.
Once the energy is in the far field region - they have basically left the near field nest.
Their ability to influence the feedpoint impedance is very minimal in the far field region.
At this point they are a fully grown up electromagnetic radio wave.

This is why many people advise taking field strength measurements at sufficient distance to ensure you are in the far field.
Unfortunately, many of us living on small suburban plots would find this very difficult.
So my advice is - any measurements of field strength are better than none.
And in my experience, as long as you have a path clear of distorting metal structures - the measurements of near field strength are fairly indicative of performance.
Of course get the most distance you can - but don't avoid taking field strength measurements just because you can't get 1 wavelength distance.

The point of the above novella is to urge antenna experimenters to consider field strength measurements as an even more important part of antenna assessment than SWR.
SWR matching is nothing more than impedance matching from the antenna impedance to 50 ohm feedline in most cases.
It does not affect antenna pattern or antenna efficiency at all - it is a really trivial part of the antenna equation.
SWR only affects feedline loss - end of story.

So get those cheap CB SWR meters out of the closet and use their field strength function - it will lift the cloud of uncertainty around how your antenna is really radiating.

73 - Rob


Title: RE: Dipole vs. Vertical
Post by: N4JTE on November 26, 2012, 03:13:04 PM
Rob that is one of the best explanations of verticals I have read anywhere!
Good solid information.
Bob