FAN DIPOLE

[flintstone mop]

The December issue of QST has a wonderful solution to a fan dipole.

Using plastic DEER FENCING.
Looping the antenna wire through the fencing. Start with the lowest band on top and work your way down.

The article is titled Upside Down Wedding Cake antenna.
Author claims there is no interaction between elements.
Operation of a resonant antenna good from 40-10m.
I think he ran a separate wire for 15m. He could not get the 40m element to give him 3rd harmonic for 15m.

[WD8BIL]

He could not get the 40m element to give him 3rd harmonic for 15m.

That indicates his claim of no interaction is false!

[W1ITT]

That the 40m dipole doesn't give good results on the 15m band does not necessarily relate to interaction with the other elements, although it might.  Typically, the 40m dipole will give a resonance a bit above the 15m band due to "end effects".  In the good old days when only rich guys had an SWR bridge and most of us had output networks with variable components such as Pi-Networks or link coupling, we could twist the knobs and make a 40m dipole work on 15 meters, sorta, at least good enough to get on the air.
Now that every Tom, Dick and Hiram has an antenna analyzer, and a transmitter with transistors meant to only feed a 50 ohm laboratory standard load, we have come to see the errors of our naive youth.  Despite our ignorance, many still have boxes full of QSLs.  Perhaps the whizbang automatic antenna matchers on our Rice Boxes will sort this all out for us. 
Our first snow of the season came during the night and my wire antennas look like the hawsers that tie the fishing boats in Portland Harbor.  My worry about this fellow's fancy multiband antenna is that it would catch enough wet snow to pull down the outhouse chimney.  I recently installed a full sized 2-30 mhz receive antenna for an overseas customer.  It was a broadband fan dipole with complications, and I just squeaked it in below the 2.5:1 SWR spec.  I have learned not to be too critical of hams who attempt to build multiband wire antennas, as even the things that hams do, although not perfect, probably show better performance per dollar than some of the "professional" stuff.  It's just that the pros demand  performance beyond the point of diminishing returns, while a ham's budget soon makes him settle for "good enough".

[WD8BIL]

Maybe so but I've never had a 40M dipole that I couldn't use on 15M. Anecdotal.... perhaps. In fact, the fan dipole I have up now for 80/40 also works quite well on 15M.

Interaction and height above ground are the 2 factors that need to be controlled here.

[Steve - K4HX]

The bigger question - why aren't we having this technical discussion in the Technical section? 

[WD8BIL]

Cause I can't move it?

[KL7OF]

I just wonder if the deer care because you are using their fence!!!?

[flintstone mop]

The bigger question - why aren't we having this technical discussion in the Technical section? 

Hi Steve

My fault. It didn't seem to be really technical, but now that you brought it up...............

[flintstone mop]

Maybe so but I've never had a 40M dipole that I couldn't use on 15M. Anecdotal.... perhaps. In fact, the fan dipole I have up now for 80/40 also works quite well on 15M.

Interaction and height above ground are the 2 factors that need to be controlled here.

THAT was another issue brought up in DEC QST, "Hints and Kinks" or whatever.
Someone had the same problem with a vertical on 40m that would not accept the 3rd harmonic. (15m)
There were tech issues, that I would have to read a hundred times, explaining why it didn't work and what to do.
Interaction was between the antenna elements. He reproduced a the readout of his analyzer, and it gave a clear dip and rise of resonance between bands......

My 1/4 wave vertical, for 40m operates on 15m, perfectly. Not tuning networks.

[W2PFY]

Does anyone have a picture of this or a similar one since there may be copyright BS with the source? I can not picture this thing in me old head?

I wonder if there is any dielectric loss using this fence as a spacer? Years ago I came across some large catheter tubing that must have been manufactured for livestock?

I put it in line as a feed-through through a overhead door-sill to a long wire antenna. I keyed up my BC-610C on 75 meters and noticed a bright blue glow lighting up the whole plastic tube? I found out that it was electroconductive as they used RF to extrude the tubing. I'm thinking there must be some kind of metal in it? I removed it because I didn't know if it would cause a fire?

Therefore the question about any losses due to how it is manufactured?

Over 

[flintstone mop]

The deer fencing is plastic and there wasn't any detuning noted.

http://www.homedepot.com/p/Easy-Gardener-7-ft-x-100-ft-DeerBlock-Protective-Mesh-6050R/100328622

The antenna wire was interwoven through the fencing. Lowest band on top and the author had a separation of "3 GRIDS, maybe 4" between elements/bands.

The material was cut long enough to support each element/band.
Looked like an UPSIDE DOWN WEDDING CAKE.

Someone mentioned that the fencing material could become a problem collecting ice and snow.

I guess there would be copyright problems grabbing something out of QST and pasting it here...

I thought everyone got QST......they have articles for AM ......

[N5RLR]

Hmm…reminds me of a discussion I saw years ago (maybe here, definitely somewhere) about using "electric horse-fence tape" (poly webbing with bare wire interwoven) as antenna elements.  I recall someone remarking about pruning the different wire runs therein to various bands.
 
I wonder how this deer-block fencing would fare long term out in the elements, UV, etc.

[KD6VXI]

Those horse fence antennas are great.

Super small (28 or less)  gauge and stainless steel.

A dummy load also radiates.

--Shane
KD6VXI

[W3RSW]

The first wet, sticky snow or lightest ice storm will see a horizontal wedding cake down on the yard if one of these is put up in northern clime,  buried and one with the frozen grass. Read the article and think for summer use it's pretty neat.

[KB2WIG]

I use a 80/40m fan dipole stuck between the trees. The 40m part is actually part of a "u" now as the pipe wrench holding the end up came down last spring. But it still works well. I don't think I would be a fan of the deer fencing thing up here in snow land.

klc