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Author Topic: Verticale Dipole Hf  (Read 4047 times)
ON5RKN
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Posts: 6




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« on: November 27, 2012, 11:15:50 AM »

A simple antenna, easy-to-make, with reportedly reasonable to very good results
... a vertical dipole. Zero Five, Force12, Titanex and a dozen others all have
one or more antennas according to this principle. Sometimes even in a linear loaded form.

http://dj0ip.de/s/cc_images/cache_2411601030.jpg?t=1327514127

Titanex claimt: This antenna has very good characteristics, a low radiation angle, exceeds a usual vertical in gain and doesn't need radials.
It can be used on ground proximity, on towers or roofs. If you set up the vertical dipole close to ground, the ground will act like a reflector.
The flat radiation of the VD8010(E) is very characteristic especially on 40 through 10m and makes it to an antenna which is favorably useful for DX traffic.

Does anyone have experience with this type of antenna, the use and possible DIY?
all tips and tricks are welcome

73's ON5RKN
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K3VAT
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Posts: 709




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« Reply #1 on: November 27, 2012, 12:14:24 PM »

A simple antenna, easy-to-make, with reportedly reasonable to very good results
... a vertical dipole. Zero Five, Force12, Titanex and a dozen others all have
one or more antennas according to this principle. Sometimes even in a linear loaded form.

http://dj0ip.de/s/cc_images/cache_2411601030.jpg?t=1327514127

Titanex claimt: This antenna has very good characteristics, a low radiation angle, exceeds a usual vertical in gain and doesn't need radials.
It can be used on ground proximity, on towers or roofs. If you set up the vertical dipole close to ground, the ground will act like a reflector.
The flat radiation of the VD8010(E) is very characteristic especially on 40 through 10m and makes it to an antenna which is favorably useful for DX traffic.

Does anyone have experience with this type of antenna, the use and possible DIY?
all tips and tricks are welcome

73's ON5RKN

I didn't see where you listed your operating goals: the bands of interest and if you're primarily interested in DX'ing or just chatting with the locals.  The link photo reminds me of a variation of shorty G5RV with some of the dimensions altered.

Vertical dipoles are, of course, vertically polarized and do well if ground condx are good, especially in the farfield.  They are traditionally mounted with the bottom half of the radiator close to ground, and with the feedline coming off at right angles (as shown in the diagram) which often is a mechanical problem (how to support the horizontal feedline).  All multiband vertical dipoles, just like horizontally polarized dipoles are compromise antennas.  And depending on how you mount them (height in the case of horizontally polarized) will perform well or awful.  Having the bottom half of the radiator so close to ground can be a safety problem for people and animals (as the end is very 'hot' or you can run into the wire by mistake).

IMHO, one of the few experts of the vertical dipole is Tom Schiller, N6BT who was the founder and Prez of Force12 Antenna before it was sold.  He designed the Sigma Series of antennas along with a series of vertical dipoles using sloping 'radials'.  Much of his original work was incorporated at Team Vertical which set many world records using non-yagi antennas at ocean side locations in major contests.  See his site at  http://n6bt.com/for the story and their records behind Team Vertical.

In fact, Tom has a new vertical dipole out that uses an innovative method of sloping radials, and a feedpoint configuration where one can simple attach your 50 ohm coax and run the coax straight down the antenna base support to the ground and over to the shack.  These antennas work.  Ask Chuck, NI0C.  

If you want to enhance a vertical dipole's performance, then one can employ traps (several pairs are fine).  Today's high-performance traps are actually quite low loss (<0.5 db typically) and really work despite claims otherwise (mostly by antenna manufacturers who discredit them in order to promote their own sales).  I've use trap dipoles and have DXCC on 3 bands with this arrangement.

In summary, the vertical dipole whether monobander or multibander can be very workable antenna, but one must be cognizant of antenna layout, ground condx, safety issues, mechanical issues, etc.

GL, 73, Rich, K3VAT
« Last Edit: November 27, 2012, 12:37:38 PM by K3VAT » Logged
N6AJR
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Posts: 9908




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« Reply #2 on: November 27, 2012, 03:46:23 PM »

Make your own verticle dipole.  for 10 meters you need  a pair of wires about 8 feet 6 inches long and a piece of coax to feed it. Run the coax at 90 degrees  to make a horizontal T for a wave length or so. bingo. verticle dipole.  add a couple more wires on the bottom and spread them out and you have a quarter wave vert. 
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WB6BYU
Member

Posts: 13248




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« Reply #3 on: November 27, 2012, 04:10:10 PM »

The vertical dipole shown in your link should work fine from 10m down to 40m as long
as you can keep the feedline perpendicular to it for some distance.  That's about the
minimum practical length on 40m, and you may have problems matching it with some
lengths of feedline.


Efficiency will be improved if you can raise the bottom another metre or two due to
reduced ground losses.  Safety is improved if you can get the bottom up out of
reach of people or protect it from accidental contact.  (Running it inside a large
diameter plastic water pipe will help.)

Performance (especially for DX) will vary with local ground conditions:  very good by
the ocean, unremarkable over dry, rocky soil.


One of the biggest problems with vertical dipoles is preventing coupling between
the coax and the bottom half of the dipole if one can't run the feedline horizontally
to the antenna.

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W5WSS
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Posts: 1727




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« Reply #4 on: November 27, 2012, 08:05:57 PM »

The 1/2 wave vertical dipole is better balanced when make the feedpoint relative to the two legs centered in the middle.

We usually feed it at the center,and is best when we are designing a system for multiband service even when we feed it with balanced line while maintaining balance can be an installation challenge,includes routing the balanced line perpendicular relative to the two equal legs.We also benefit best balance with a good 1:1 current balun just before entering the shack and convert to 50 ohm coaxial cable and run short length to the inside for connection to the tuner.

Or for mono band service we can treat the 1/2 wave dipole in the following manner:

I made this for a hilltop mobile see my callsign picture here at eham.

We can split the bottom half into 4 or more equal parts orient them at a downward 45 degree sloping angle symmetrically and center feed with coax and have a vertical dipole that is close to 50ohms and omni directional.The bottom second leg being split helps set the feed point Rr and actually contributes to the sum of the total far field radiation regardless of what obstructions exist out of our control.

A 1/4 wave ground plane is when we split the second 1/4 wave half (Shield driven) of the center fed antenna into 4 equal parts but orient them in the horizontal plane.In this method our elevated radials cancel each other but do not contribute to radiation in the pattern.
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ON5RKN
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Posts: 6




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« Reply #5 on: December 01, 2012, 09:46:49 AM »

Hi Robert

this is a multiband variation

http://www.mydarc.de/dk7zb/Vertikal/tripleleg.htm
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K3VAT
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Posts: 709




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« Reply #6 on: December 01, 2012, 04:01:26 PM »

Hi Robert

this is a multiband variation

http://www.mydarc.de/dk7zb/Vertikal/tripleleg.htm

Ah! Good Olde German Engineering!  And I like the mod to the SGC autocoupler.  Thanks for the link.
GL, 73, Rich, K3VAT
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W5WSS
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Posts: 1727




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« Reply #7 on: December 01, 2012, 08:50:00 PM »

Hello On5rkn, Nice...see my picture of a 20m one that I built for a mobile hilltop here in eham at my callsign.

I also built a 15M version for a vacation cottage this past summer and both worked extremely well.
73
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SM5JAB
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Posts: 11


WWW

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« Reply #8 on: December 03, 2012, 01:39:41 PM »

My first antenna experiments were with a vertical dipole: http://www.da.isy.liu.se/~mj/HAM/ANT/

It works all-ok even with my modest installation.
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ON5RKN
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Posts: 6




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« Reply #9 on: December 04, 2012, 12:59:01 PM »

Nice Setup Michael (SM5JAB) can you give a litle more details please

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SM5JAB
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« Reply #10 on: December 06, 2012, 12:23:40 PM »

Nice Setup Michael (SM5JAB) can you give a litle more details please

Well, there's not much more to it. The antenna was made from 1 in square aluminium rods. The ladder line home made as per the pictures. It stood on half-a-meter piece of wood just to keep it off the ground. Mostly I used a old E-ZEE Z-match for tuning.

It worked much better than anticipated really. It is so deceptively simple. With wires you can end-load it capacitively and lower its resonance quite a lot (even to other bands!).

/Micke
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