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Manager - AB7RG
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Zig-Zag Dipole

Created by on 2008-10-24

OK, I've never seen or heard of one of these and have wondered for years if it would perform decently or end up a waste of time.

My proposition for a stealthy low-band dipole, made-to-fit in a small yard, is hanging the center-feed point dead center over the back yard. It would be coax fed and have both a voltage balun and a common mode current choke.

The 1/4 wave wire on each side would depart from the center at a very steep horizontal angle, and 180* from the other side, each headed for one of a set of catenary lines stretched across both the rear and the front edges of the 70' wide, 30' deep back yard.

They would each then zig-zag back and forth from the front catenary line to the rear in a mirror image of the other side, making a lightning-bolt looking leg on each side.

Some might call it an "Accordion Fold."

The entire antenna could only be a maximum of 24' high throughout, and I know that's low for 160m, but without a tower nor other way of hanging the 275' of dipole, I would have to take what I get.

Any thoughts, (or preferably) experience with this design?

I have also thought this could be made to work as a stealthy attic antenna for 80m, 60m, 40m, etc., IF it will work well enough to warrant the effort.

Tnx & 73
Scott KC6O

K4BTC 2009-12-28
RE: Zig-Zag Dipole
AMEN!! thank you for what you said. Some people on here exist solely to flaunt their superior intelligence. Geesh, if you don't have anything to add to the question or solution, please don't add to the problem.
PLANKEYE 2008-11-11
ARROGANT BOB
KB6QXM:

This question is another example of the failing of the present license requirments.

The need for a more technical license requirement, so that we do not experience questions that are not technically sound!!

Ok OK, you want to drop the CW requirement as no one seems to have the disipline to learn the art...fine, but ham radio is a technical hobby and to "advance" the art of radio radio communications, you need technically sound participants.

73


________________________________________________

PLANKEYE:


Hey check this right quick Dude!

My boy writes an article and all you can do is tear him and the article apart.

The next time you blaze down on dudes, Robert not Bob, spellcheck your stuff!

When you don't, it turns your arrogance into ignorance!!

Anyway, enjoy the hobby and have fun guys.

And remember, IT'S A HOBBY!!


Keep the Whiskey out the Wires Fellas, I got to go!!



PLANKEYE










KB6QXM 2008-11-11
RE: Zig-Zag Dipole
Not that long ago hams did not have to apologize for not knowing much.

The license exam ensured that they had a basic understanding of electronics and other related technologies.

We are in a brave new world!

.....and they call this progress??????
K4TLJ 2008-11-09
Zig-Zag Dipole
Being a new ham and not 'knowing any better', I use an antenna that I put up several years ago for SWL. It is approximately 59 feet over all. The antenna could be described as an end fed long wire with a twist ('zigzag'). It exits through the wall behind the radio, turns 90 degrees and goes diagonally upward to the soffit , takes another 90 degree turn and goes diagonally upward to the peak of my shop and then turns about 30 degrees and slightly downward to a tree 30 feet away. The ground is a copper pipe driven in the ground about six feet. I have dumped several boxes of salt on the dirt around the ground rod over the years.

I do not have a tuner. I loads almost perfectly on 75 meters and loads on 40 and 20 well without the tuner.
WD2I 2008-11-06
Zig-Zag Dipole
I think the easiest way to build a dipole, is to put up as much wire as you can, feed it with 450ohm ladder line or as I prefer homebrew 600ohm open wire line, then to a 4:1 balun. Run the coax as short as possible to the tuner and there you have it. Works every time.
KI6JJT 2008-11-02
RE: Zig-Zag Dipole
Scott, if you need help putting this up, email me at ki6jjt@xtechs.org I do not live far from ya.
KC0ROM 2008-10-31
RE: Zig-Zag Dipole
AN ANTENNA OF THIS DESIGN WILL WORK BUT YOU WILL HAVE REACTANCE POINTS TO CONTEND WITH,YOUR SWR CURVES MAY BE ERRATIC. BUT IT WILL WORK IF YOU HAVE NO OTHER OPTIONS.HOW WELL IT WORKS MAY BE ANOTHER STORY. KC0ROM SCOTT
FORMER_KC6O 2008-10-30
RE: Zig-Zag Dipole for High Rise Building Balcony
Thanks to all who spent the time to read and reply, even the clowns who serve as a reminder that not everyone can have a personality.

Bonnie, are you still world traveling or have you settled there in Hong Kong? Thanks for that anecdote, and I hope to soon work you DX.

Dan, I appreciate your offering and all the others. I'll hopefully have the concrete poured, poles erected for running the catenary lines and the ZZD up within a month or so, especially if the rain continues, I need it to soften the ground under my shovel!

73,
Scott
W5WSS 2008-10-29
RE: Zig-Zag Dipole for High Rise Building Balcony
k0bg just to set the record straight that's cool But here's my point about the continuosly coiled doublet. It radiated a high percentage efficiently, based on extensive tests. Therefore it is not a heating coil or a resistor as w8ji was explaining to others. I do not either recommend nor discount it as a feasable solution to a percentage of hams with space restrictions but rather want to point out that a continuously coiled doublet offers a specific utility to some. regards 73
WB2WIK 2008-10-28
RE: Zig-Zag Dipole for High Rise Building Balcony
I tried the zig-zag but mine would only zig.

I think that's because I was reading a book by Zig Ziglar and the stars influenced antenna behavior.

Will try again later.

:-)
KQ6XA 2008-10-27
RE: Zig-Zag Dipole for High Rise Building Balcony
Hello to Scott KC6O,

I've had good success with a Zig Zag Dipole on the balcony on a mid-level floor of a high rise hotel, while operating HF during a business trip.

I suspended a thin black wire dipole in a diagonal "Z" shape, between the overhanging ceiling, railing, and various other parts of the balcony. The feedpoint was arranged in the midpoint, in the clear at the outermost part of the balcony. Gaffers tape and black nylon string was used to hold the dipole in place. The wire was arranged and bent at angles so that it was only close to the building structure at a few angle points, rather than parallel to it. This maximized the "free" field of the antenna... in general terms, the concrete/rebar construction of the building tends to dampen the RF field of the antenna somewhat if the wire is too close to it.

I tuned the Zig Zag Dipole antenna to resonate on 14MHz, and used 50 ohm RG-174 mini-coax to feed it, with the coax wrapped on a miniature toroid ferrite (7 turns), one at the antenna feedpoint, and another ferrite inside the hotel room at the radio end of the coax. It provided a good SWR without a tuner, and the ferrites helped to isolate the antenna from conducted EMI noise within the building, reducing interference to the hotel cable TV system, and suppressing HF receive interference somewhat. As expected, I was able to work DX on 20 meters, in every direction except what was blocked by the building.

It is probably more important to use some type ferrite balun or ferrite coaxial choke on the feedline with such Zig Zag antenna structures, especially when in close proximity to other objects. The impedance of a Zig Zag dipole is often somewhat lower than a straight dipole, and imbalance is often encountered, which leads to more tendency for RF to flow by skin effect on the outside of the coax feedline. Depending upon how much the dipole is squashed by the angular arrangement, the impedance is more like 25 to 50 ohms, rather than the characteristic 72 ohm straight dipole in "free space". This actually provides quite a good match to 50 ohm coax directly, without need for an antenna tuner.

The same technique of Zig Zag elements can be used for radials of ground plane antennas. I am currently using Zig Zag and folding arrangements on several of the radials of a Butternut HF9V antenna, on top of a building, with wonderful results.

Zig Zag, angular, and 3-dimensional bending, can often be used to fit a wire antenna within the constraints of a real world antenna environment. I encourage you and everyone who encounters such a situation to try it. It works.

73 Bonnie VR2/KQ6XA
Hong Kong
W8RPE 2008-10-27
RE: Zig-Zag Dipole
"RE: Zig-Zag Dipole Reply
by KB6QXM on October 26, 2008 Mail this to a friend!
This question is another example of the failing of the present license requirments."

AMEN!!!
N3DG3 2008-10-27
Zig-Zag Dipole
Per Antenna Expert L.B. Cebik W4RNL at:

http://www.antennex.com/w4rnl/col0507/amod111.html

...if I interpret correctly, a Zig-Zag Dipole is about 2 dB better than an isotropic reference dipole with a negligible difference over a standard reference dipole which has 2.15 dB gain.

This means a 45 degree Zig-Zag Dipole loses only like 0.15 dB difference over a standard dipole which amounts to no noticeable difference in signal strength whatsoever.

73,

Dennis
N3DG
N3DG3 2008-10-27
Zig-Zag Dipole
Hi Scott !

Probably like you, I live on a smaller lot and do not have room for a full-size 160 meter dipole without bending her. Also like you, I suppose that a proper ground plane even on the ground is not realistic, stealthy and is definitely messy.

For a while I just tuned my 80 meter dipole on 160 with a tuner. The tuning and bandwidth was very sharp, but I worked from Russia to Hawaii with it. Weak signals were obviously not heard very well compared to the others.

So I pondered like you if a zig-zag would work or improve. What the heck, wire is cheap enough.

So I tried it and installed it in the Spring. The band came to life and the antenna was much easier to tune. I would have to say there was at least a 3-4 S unit improvement over the half-sized dipole which was cut for 80 and I have much less RF around the shack as well. I know I am hearing and working much more. My arrangement is a fan dipole with 160/80/40/30 with the apex at like 30 feet and then down to a tree at like 15 feet at the bottom sides/ends. I just use a plain center insulator with an RF choke as I don't like baluns, having shorted them out with even just 100 watts.

It is not very high and I guess there are ground losses and a higher angle of radiation than optimal as I believe I am not hearing as well as a end-to-end dipole at 60+ feet, but you will like the results, minimal effort and cost. You will also get losses in coils and tuners, this is simpler, cleaner and cheaper, I think. A model would be a good idea just to see, I have not, but it's still worth 270' of wire, some insulators and an hour or so.

I also wondered about a 80-135 foot vertical just by having a wire dropped down and maybe stapled to my large tree (allowing slack for growth) and a coil or matching network (like SGC) at the bottom, but that would require a messy ground plane of radials too so never did that.

Don't be discouraged by the grumps and snobs...give it a go Scott !!!

You will get results and be on 160 effectively with a zig-zag dipole. In fact, antenna companies even use this approach. Take a look at the SteppIR yagi with the 40 & 30 meter add-on kit which adds a rotatable dipole for 40 & 30 onto the driver element, which actually very acutely folds back onto itself. It works, to say the least.

73,

Dennis
N3DG
FORMER_KC6O 2008-10-26
RE: Zig-Zag Dipole

Reply by KB6QXM on October 26, 2008

"This question is another example of the failing of the present license requirments.

The need for a more technical license requirement, so that we do not experience questions that are not technically sound!!

Ok OK, you want to drop the CW requirement as no one seems to have the disipline to learn the art...fine, but ham radio is a technical hobby and to "advance" the art of radio radio communications, you need technically sound participants.

73"

In expression of your obvious intellectual superiority you misspelled 'requirements' and 'discipline', perhaps you should either learn to spell, or learn to use a simple spell-check program as do so many 2nd graders.

Thank you for your uplifting addition to this format, and may we all strive to be so elevated, not only in our achievements, but in our own minds as well.

Thank you, Bob, for your encouraging consideration. You are obviously a man of greatness.
FORMER_KC6O 2008-10-26
RE: Zig-Zag Dipole
Hello Bonnie!

Thank you for your response & the link, it's quite informative and helpful. I see why I've heard so many say they consider you an authority on workable antenna designs.

73 & enjoy your travels.

I appreciate everyone's input, lots of great info & ideas.

- Hams helping & encouraging other Hams, that's what it's all about!

I've enjoyed (almost) all the responses to this, my first article. I've decided to build it and give it a try.

73,
Scott KC6O
K2WH 2008-10-26
RE: Zig-Zag Dipole
A Zig-Zag will work just fine but feed it with ladder line and a tuner. I have direct experience in this type of antenna you describe. A 160 meter dipole on a small lot, feed point right over the center of the house, each side went as far as it could go and stay on the property then at a obtuse angle the other way and so forth. The best way to describe it is to look down at it from above, and it was a big letter "Z" with the center of the "Z" over the house and the upper and lower horizontal part of the "Z" running along the property lines.

Worked and I have confirmed so far, 48 states on 160 and 20 countries, DXCC mixed, WAS and WAC with this antenna and it is only 20-30 feet off the ground. I also used the antenna on all other bands with the tuner. It will work.

K2WH
KB6QXM 2008-10-26
RE: Zig-Zag Dipole
This question is another example of the failing of the present license requirments.

The need for a more technical license requirement, so that we do not experience questions that are not technically sound!!

Ok OK, you want to drop the CW requirement as no one seems to have the disipline to learn the art...fine, but ham radio is a technical hobby and to "advance" the art of radio radio communications, you need technically sound participants.

73
W5WSS 2008-10-26
RE: Zig-Zag Dipole
The best area of a doublet that would better be straight is the area that carries the current yes that is correct if one could and still wants to use coiling then the best area to incorporate them is out past the current area.
W5WSS 2008-10-26
RE: Zig-Zag Dipole
The least space for a linear dipole would be a specific length for a resonant dipole. The coiled one is understood to be a compromise between the two. yes it is correct that if one were to next stretch the continuously coiled legs out then it would not fit into the space available.....and would become a dipole so the fact that there is a difference in performance has already been established but if the shoe fits then wear it. The coiled legged doublet since it is used as a multi band horizontaly oriented horizontaly radiating antenna will follow conventional properties of radiating albeit at lower gain,lobe volume pattern forming etc than the comparative dipole with straight elements which I wonder why the comparison was posted since the issue was in fitting the antenna into a space too small for straight legs in the first place...yes the continuously coiled doublet will work radiating lessish than a dipole used at the same frequency for example. The utility of the continuously coiled doublet remains the same regardless. Lest there be any confusion I do not say the antenna is better than a conventional linear legged dipole of course the linear legged dipole(single band) or doublet as a multi band offers better performance in all, but like all things if it doesnt fit into a hams available space it is not an option = zero utility.
W5WSS 2008-10-26
RE: Zig-Zag Dipole
A correction to my earlier post the coil diameter was 20" rather than 10" I looked at it yesterday and measured them. Memory eludes me sometimes anyway it was 5 yrs ago that i built and used the continuosly coiled doublet.
K9FON 2008-10-25
RE: Zig-Zag Dipole
I run a 270' doublet for 160 80 and 40 meters and my ends are zig zagged around a bit and my antenna works just fine and dandy. I didn't use some silly ol' mind numbing formulas, ez nec, or whatever i just built it put it up and tuned it with the trusty ol' tuner and eveything works for me!
N4JTE 2008-10-25
RE: Zig-Zag Dipole
First of all this is not an ARTICLE, at BEST it's an elmer question.
Sure, at 24 ft.high you will work every TV and phone including your own, in the neighborhood. No offense to the "Author" but any horizontaly configured antenna, no matter how you try to shorten it, needs to be as high and as long as possible relative to the freqency of choice to work beyond the backyard; Antennas 101.
Bob
K6VHP 2008-10-25
Zig-Zag Dipole
Scott, please seek therapy. Maybe Mr. Benson can help.

8-)

G0GQK 2008-10-25
Zig-Zag Dipole
I have seen a design for a zig-zag end fed, I've just been trying to find it but not been able to locate it.
With a garden area 70 ft X 30 ft it is difficult to have an antenna which is good in such a small area. Most of the suggestions seem to have forgotten how small your plot is.

Suggest a 1/4 helical with 248 ft of 12/14 gauge insulated copper wire. I have construction details if you contact me.

Also a half size sloper which requires a 40 ft high support which is resonant in the CW section.

An inverted L 35 ft vertical, but 100 ft horizontal everything for 160 is big .

I think you might have to go for a helical, I know of designs which used a 6 inch dia, cardboad carpet tube which was varnished and theuser said it got him around.

Mel G0GQK
KI4UCO 2008-10-25
RE: Zig-Zag Dipole
the suggestion of a coil loaded dipole is a good one. i have built several of these and they work very well. here's a web site that will be of great help if you decide to go this route:
http://www.k7mem.150m.com/Electronic_Notebook/antennas/shortant.html#Page_Top

here's another alternative for a 160 meter antenna:
http://www.iw5edi.com/ham-radio/?a-practical-antenna-for-160-metres,32

Good luck!
Todd
K0BG 2008-10-25
RE: Zig-Zag Dipole
Just to set the record straight, the coiled loaded dipole I spoke about above, would have been better described as a trapped dipole. While perhaps slightly less efficient than a non-trapped one (on its lowest band of operation), average joe ham would never notice.

Why they have fallen out of favor, in favor of a G5RV or doublet, is rather moot, and one argument I won't foster.

Alan, KØBG
www.k0bg.com
K8KAS 2008-10-25
RE: Zig-Zag Dipole
A 20 foot high dipole on 160 meters is worthless in my book, I have operated 160 meters for over 40 years and the Inverted L is the way to go IMHO, I use 18 ga copper clad steel wire and you can't see the stuff, you should have a few radials (more the better) since it is a current fed antenna. My present system is an 84 foot Inverted U with 30 --50 foot radials under it and matching network at the end. It works very well local and DX on 160m and I can tune it on the other bands as well. You have to look very close to see the antenna outside my small lot. 73 and have fun..Denny K8KAS
AG4DG 2008-10-25
Zig-Zag Dipole
Sounds better than a Hamstick dipole. A Hamstick dipole for 75m is a joke, and I can't believe RACES and AREs advocate these.

Yes, I have tried a 75m dipole for the state 75m net. Here are the things I have against this:
1. Most fundamental: Nobody more than about 5 miles away could copy me.
2. It's not a single-band antenna but a single-frequency antenna. You're lucky if you can QSY more than about 10 kHz from the resonant frequency. Thus, it is VERY tricky to adjust the two whips properly. Forget about using a tuner, as the antenna is EXTREMELY touchy, and even if the antenna analyzer shows a decent match, it won't stay that way when you transmit.

A zigzag dipole for 75m is FAR better than a Hamstick dipole in the clear.
W8JI 2008-10-25
RE: Zig-Zag Dipole
EM radiation comes from charge acceleration. Moving charges are current.

You always want maximum current moving over the maximum linear spatial distance. You always want as much current flowing in a straight line as possible between the two most physically distant points.

The best advice is keeping the high current area as straight as possible. Secondly, the antenna has to matched to the rest of the system with low loss.

It has NOTHING to do with how much wire you fold into a compact area, so long as the high current area occupies the maximum possible spatial distance and you can couple power into the antenna with minimal loss.

The antenna would be much better off if the zigs and zags were only at the open ends, where current was low. Technically the best form would be a large capacitance hat at the open ends with a solenoid coil of high Q for any additional loading needed. A fold or zig-zag is not the best system, not by far.

You actually want the LEAST amount of wire in a given area that allows resonance, not the most. You only want the most conductor length in a small area if you are building a resistor or an electric heater.

73 Tom


W9OY 2008-10-25
RE: Zig-Zag Dipole
If you use a ZIG-ZAG dipole you probably need a Prince Albert in the Can balun

73 W9OY
K5END 2008-10-25
RE: Zig-Zag Dipole
Try it and see how it works.

Because you used the word catenary, I assume you are aware theoretical physics and experimental physics are required, much like a coin requires two sides.

A negative verification is equally important to one that works.

Watch out overhead for falling quasi-trigonometric hyperbolics, haha.
W5WSS 2008-10-25
RE: Zig-Zag Dipole
Alan I built exactly as you described. I made coiled legs both sides of center. The wire length for no paticular reason except that it was already available was 44'x44' center fed.I made The coil size 10' dia. and it fit nicely on my interior ceiling! The performance was reasonable for a horizontal doublet made entirely continuously coiled. The spacing between coils would change the matching at the feed point terminals but all in all I was fairly impressed with this approach I fed mine with Belden 300 ohm transmission line I was impressed with this doublet as a multi band affair. I hung the entire thing diagonally across the area and the height was only 18' so on 20 the pattern exhibited the expected high angle towards the zenith...I made contacts in an omni directional fashion so most of the properties that are found in a low horizontal antenna held true as this interacted with the ground the bi directional characteristics normally expected from a horizontal antenna that is high enough are not met at this low height. The pattern developement of a low horizontal antenna is expected to be high toa and lessor gains but will be omni directionalish,and nvis on most bands but perhaps 10 meters were 18' is a half wave high.(when I did this it was during the worst period of no signals on 10m so I did not determine its dx ability on that band at that height.) and the coiled doublet was no exception to these interactions to earth surface proximity. So the utility of such an doublet is to be determined by the users needs but I think there is such a place in a percentage of hams today. Good suggestion Alan. Regards 73
KQ6XA 2008-10-24
RE: Zig-Zag Dipole
Zig Zag Dipoles are well known.
Here is a web page with some antenna modeling on it:

http://www.antennex.com/w4rnl/col0507/amod111.html
KC0RBX 2008-10-24
Zig-Zag Dipole
Scott, sounds kinda cool. Ya know what you're describing is done on a very small scale (so to speak) with another field of antennas, Fractals. Now, there is controversy on that subjec, imagine that. However, fractals are manufactured and used in very small transmitter applications. I would research Fractals a little and I would also apply as was suggested your design to EZNEC. I'm no antenna guru, so take my thoughts for what they are worth.
N3JBH 2008-10-24
RE: Zig-Zag Dipole
AMEN !!!
AE6CP 2008-10-24
Zig-Zag Dipole
You guys and your autotuners!

Put up a doublet as high as you can, make it as long as possible, fold the legs as needed as long as the wires don't cross and both sides are mirror images of each other. Feed it with 450 Ohm window line and tune it with a balanced double L tuner like the Palstar BT-1500A.
K0FF 2008-10-24
Zig-Zag Dipole



As long as the middle half of the antenna is pretty much straight, the outer parts don't matter all that much ( in my opinion of course). The current part of the antenna is in the middle, where we generally feed them.

The end parts don't radiate much, but tremendous voltages build up, especially at the very ends, so be careful from a safety standpoint.

Turn the whole antenna on its end and you have a vertical dipole, and as we all know, the lower half can be replaced by a counterpoise ( being grounded or not does not matter much.")

Now that you have a vertical, the top half of that 1/4 wave can be significantly shortened without changing the radiation patter much, as long as it is shortened from the top, not the bottom.

This means top loading, not base loading. There has been a lot of discussion in antenna books that both supports and denies this, but it makes sense to me.

If these principles are followed, relatively efficient shortened antennas can be made. The fact that the SWR is low has nothing to do with how well that antenna will work by the way ( read REFLECTIONS by Maxwell)


Geo>K0FF
W7MJM 2008-10-24
RE: Zig-Zag Dipole
300 ohm twinlead from the antenna to a tuner is an excellent idea; even better would be ladder line (either 300 ohm or 450 ohm, or open wire 600 ohm line). The tuner should incorporate some sort of balun, or a choke balun can be placed between the tuner and the rig (where it will be operating under low SWR conditions assuming the tuner is properly tuned).

Another possibility is to transition from ladder line to coax (via a W2DU style current balun or a coax-coil choke balun) and then use a short length of coax into the shack where you attach it to the coax output of the tuner. That keeps RF out of the shack and avoids the problems encountered when you feed ladder line into the shack. Keeping the coax section of the feedline short in such an arrangement keeps feedline losses down to a minimum.

As for using a resonant doublet (dipole) that's a halfwave in physical length on 80 meters as a non-resonant 160 meter doublet fed with ladder line (or twinlead or open line) and matched to the transmitter via a tuner; it will work, but there will be a lot of loss in the tuner. Make the doublet at least 170 feet or so in lenght (2/3 of a wavelength at 160 meters) and it will perform much better on that band.

Another approach to making an 80 meter dipole play on 160 is to drop the coax feed perpendicularly down from the dipole center, short it just above physical ground level, and feed it against RF ground (ground radials)as a "Marconi T." That'll give you a capacitively top loaded vertical which should play nicely on 160, assuming you've created a good RF ground (the more ground radials the better). Match the system to your transmitter's output with a decent tuner, and you're in business!
WA3SKN 2008-10-24
Zig-Zag Dipole
This is an article? Looks like it would be better in the "Elmers" column!
The antenna you describe can be built. It is a compromise at best, especially the height! 24 Feet high for 160 meters is not good. However, it would load and would radiate...UP! Of course, most 160 meter antennas radiate UP!
So, string it up and start using it! Let us know how well it works. Wire is cheap!
Hope to catch you on the bands!
73s

-Mike.
N3JBH 2008-10-24
RE: Zig-Zag Dipole
I wonder why you dont feed it with 300 TV Twinlead?
it really would not be any more visable then RG-8 but with a decent tunner you have a 160 to??? antenna. to me it just sounds like great way to do it...
W7MJM 2008-10-24
RE: Zig-Zag Dipole
I've used a similar configuration for my 80 meter inverted vee.

The apex of the vee is atop a 28 foot fiberglass pole. The legs run roughly east-west and are separated by about 140 degrees in the horizontal plane, They slope downward from the apex with about a 120 degree separation in the vertical plane.

Each leg hits a 6 foot wooden fence on either side of the property; I bend one leg to the south at the fence and the other to the north, following the top of the fence. About 20 feet of each leg runs along the fence on either side of the property. I use insulated wire and maintain good insulation at the ends, where there is a high RF voltage potential.

The total length of the inverted vee is about 125 feet with resonance at 3700 KHz. At the band edges, the SWR is in the neighborhood of 2.5 to 3, well within the range of my rig's internal tuner as well as my tube amp's pi-net output.

I feed the antenna through 100 feet of RG-8x mini. At the antenna feedpoint, I have a W2DU-style 1:1 current balun and just outside the shack I've coiled the coax to form a "choke balun" (about a 5 inch diameter coil, about 13 turns).

The system works very well for regional SSB communications and has worked decently for casual CW dx-ing. It probably helps that the local terrain slopes steeply to the south and west, remaining horizontal in other compass directions.

Of course, a 160 meter version with an apex at 28 feet would be much lower in terms of wavelength, so there would be more ground loss and a greater percentage of the radiation will be going straight up. Ground loss is not good for antenna radiating efficiency, though it will increase your antenna's usable bandwidth. As for the high angle of radiation; for regional communication, that's a good thing but it's usually not so good for DX (though there are times that distant signals arrive at high angles).

Generally speaking, a vertical with a good RF ground system would be a better way to go if you're interested in 160 meter DX, unless you can get the apex of your inverted vee/dipole up at least a quarter wavelength, which is in the neighborhood of 130 feet.

You might want to look at the book "Low Band Dxing" for antenna ideas. In fact, there's a zig-zag dipole in one of the chapters!

Good luck experimenting and 73,
Martin
W7MJM
AA5TB 2008-10-24
Zig-Zag Dipole
I suggest as other have to go with an inverted-L and an autotuner. That is what I've been using for years on all bands. Most of us just simply can't get a horizontal antenna high enough (in terms of wavelength) on 160m to be very effective. On 160m anything that will give you at least a little bit of vertical component to your signal will be a big improvement.

For the higher frequency bands your plan of shorting the antenna with zig-zags should be fine as long as you don't compress the current carrying parts of the antenna too much.

73,
Steve - AA5TB
WA8MEA 2008-10-24
RE: Zig-Zag Dipole
My 160 meter dipole zigs and zags, but not like the accordion style which you speak of.

From the center insulator, the shield side of the coax goes from W to E for about 80 feet. From that point it takes an odd turn from NE to SW.

The center of the coax goes in a line out from the center insulator....NE to SW.

The highest point of the dipole is at the apex, so each side of the dipole slopes downward.

I get a 1.9 to 1 from about 1825 to 1925 KHZ with a 1 to 1 SWR centered around 1875 KHZ.

So yes, you can twist and turn your dipoles....then twist and shout after you get a got match!

73, Bill - WA8MEA
http://HamRadioFun.com
tinytenna@hotmail.com
W4VR 2008-10-24
RE: Zig-Zag Dipole
Sounds like your primary interest for this antenna is 160. Rather than going through the trouble of putting up a zig-zag antenna, why don't you install a 1/4-wave inverted L. Simply fold it over the crotch of a tree and lay down a few radials. It will work much better than what you are proposing.
WB8YYY 2008-10-24
Zig-Zag Dipole
Interesting idea, but it is hard to say whether it is the best way to use the available space and wire. Note for a half-wave resonant dipole, the bulk of radiation occurs in the center of the antenna. The zig zags will result in some cancellation that will reduce its effectiveness.

The other aspect is how you will feed the antenna, particularly if you plan to operate it off-resonance at high feedpoint VSWR. If you happen to obtain a good match at the lowest operating band you design for, it won't be matched on all the other bands.

The idea of zig zag could be employed at the ends of the antenna, where it may be more effective in giving you a useful radiator. And when you formulate something practical that would give useful radiation, the idea of modeling it is a good one.

If your interest happens to be lowband DX, a much shorter vertical radiator would be more effective, and could be disguised in some stealth fashion. It would need radials, but note these are very stealthy when placed on the ground.
WA7NCL 2008-10-24
RE: Zig-Zag Dipole
K3AN is on to something. The biggest advance in stealth antenna systems in recent times is the autotuner. It makes the remote tuning of a hidden chunk of wire a reality. Checkout the cost of many so called stealth antennas. You find that you could probably buy an autotuner for about the same cost. You then have a very versatile device that can feed all sorts of goofy radiators. If you provide a decent ground system to an autotuner, its almost plug and play.
W7ETA 2008-10-24
RE: Zig-Zag Dipole
"Any thoughts, (or preferably) experience with this design?"

WWW.EZNEC.com

Free download of a trial version--antenna modeling software.

73
Bob
K3AN 2008-10-24
RE: Zig-Zag Dipole
What supports the catenary lines? With catenaries as well as the antenna wire, multiple insulators,and a coax feedline out in the open, it sure isn't my definition of a stealthy antenna.

Ever thought of a base-fed inverted L? A flat black SGC autotuner mounted just off the ground on a wood fence or tree trunk, along with a length of #26 black insulated antenna wire and some buried radials, gives you a very stealthy multiband antenna.

K0BG 2008-10-24
Zig-Zag Dipole
Wouldn't it be nice if the world of electromagnetic waves were as simple as you outline? Unfortunately, it isn't.

While zigzagging dipoles does work to some degree, you still have to deal with unbalance in the antenna. Using a voltage balun isn't necessarily the way to do it.

One hidden problem is hanging the antenna, and there are others.

The best way is to coil load the legs, and done correctly, it is possible to have a multiband antenna that doesn't require a tuner; at least for the most part.

Alan, KØBG
www.k0bg.com