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Author Topic: 20 Meter dipole or Vertical  (Read 1769 times)
K2TPZ
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Posts: 45




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« on: February 16, 2009, 12:04:57 PM »

I'm looking for some opinions.  I have only enough room in my small Baltimore Row-House backyard for either a 20 meter sloper (or maybe a 20 meter inverted Vee), using a push-up pole at the apex or a 20 meter Vertical.  

At this point, I'm not concerned about an all band, trap vertical or the a trap dipole covering other bands.  Just looking at 20-meters, which would you prefer?  The choice is between a vertical with a decent radial field or a 20-meter wire (sloper or dipole).

If you had the choice, what would you go with?

Thanks for any responses.
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AA4PB
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Posts: 13032




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« Reply #1 on: February 16, 2009, 12:33:55 PM »

Verticals with a good radial system have a low take off angle and make good DX antennas. HOWEVER - in a Baltimore row house I expect your ground mounted vertical would be surrounded by buildings and noise generators (electronics in other houses, power lines, etc). For that reason I'd probably opt for the dipole.
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W3LK
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Posts: 5639




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« Reply #2 on: February 16, 2009, 01:49:12 PM »

Having spent 18 years in downtown Baltimore (in Federal Hill, two blocks from the Inner harbor), a vertical will work nicely, but I would put it on the roof with four or six resonant radials. I would not try to ground-mount it in the typical row-house back yard.

If you are going to that trouble, get a 4BTV or 5BTV and roof mount it with two resonant radials per band.

In my case, (an Butternut HF6V) I didn't need radials. I had a 23k sq ft corrugated steel roof as my ground plane. Smiley

Good luck with the installation, which ever way you go.

73,

Lon - W3LK
Naugatuck, Connecticut
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A smoking section in a restaurant makes as much sense as a peeing section in a swimming pool.
NK5G
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Posts: 102




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« Reply #3 on: February 16, 2009, 01:51:31 PM »

I agree with PB. if you are limited on space a dipole will serve you well.
However, you said that your only interest is 20 meters. You might rethink that. If you get a taste of what 17,15,12 and 10 has to offer once the sunspot cycle comes up you may change you mind. I'd recommend an antenna that will give you the best bang for the buck 20-10 at least. 40 if that's possible.
Two antennas to look at for limited space is the Cushcraft MA5V vertical and the Alpha-Delta dipoles. I have used both with much success. You can always build a dipole for peanuts.
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KE6VG
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Posts: 297




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« Reply #4 on: February 16, 2009, 06:13:04 PM »

A dipole if you can get it above 32 feet high. Or a vertical if you can not. A sloper would be a good inexpensive compromise also. Do you have trees you could hang wires from?
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K2TPZ
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Posts: 45




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« Reply #5 on: February 16, 2009, 09:49:08 PM »

Thanks for all the responses.  Unfortunately I have no trees and several power lines overhead attached to the rear of my house.  I do have a fiberglass mast at 22 feet that I can put in the middle of my yard to use for a dipole.  And I can put up a vertical, ground-mounted, as the Association rules do not permit roof antennas of any kind.

Across the alley from my backyard (170 feet away) I have a home brew 40-meter dipole strung between two trees.  The antenna works quite well.  The coax leading to my house is buried in the ground until it reaches the alley, then goes through a tube across the alley and then above ground in my yard to a basement window.  But it is a tenuous situation.  

No one uses that property.  I think it is a city  right-a-way of some type.  It is not a utility right-a-way.  I don't want to spend a lot on an antenna there because it might be torn down or disposed of at any time.  But my backyard is mine to do with what I want. My yard is 17 feet by 38 feet.  The measurements could easily accommodate a 20 meter dipole or a short, 16-22 foot vertical.  Taller then that would raise eyebrows and get too much attention.

I'm thinking about putting a small bird cage on top of the mast if I go the dipole route or I may try one of those flag pole verticals or even an antenna similar to the hygain 18VS.  I was just wondering if folks had a choice of either a dipole or vertical on 20, which would be their choice.  So I asked the question.

Thanks everyone
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WA7NCL
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Posts: 625




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« Reply #6 on: February 17, 2009, 08:08:48 AM »

Add a wire cut to 20m at the feedpoint of the 40m antenna.  Now you have a two band antenna.

You can also get an acceptable match on 15m with a 40m dipole.

With a tuner and reasonable coax, anything less than 3:1 should be OK.

Now you have 3 bands.
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KE6VG
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Posts: 297




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« Reply #7 on: February 17, 2009, 10:52:46 AM »

I agree, cheapest and most effective (away from buildings) Add a second 20m dipole element to the existing 40m dipole. (use any wire you have around)

If you use a ground mounted vertical in a small backyard you will be heating buildings and objects and wasting signal. If you wanted you could try one of those Harbor Freight 16' flagpoles as a 20m vertical with ground radials, but it would be alot more work than just adding a wire to the other dipole.

You also could do the bird house thing. A 12 foot 2x4 with an 8 foot T on top. (4ft each side). Nail the 2x4 to a fence or something. Hang a bird house on each side of the T. Then, run a wire from ground up and across the T. You would still need radials. 16 to 32 - 16ft radials. You will then have a T loaded vertical and people will think you are a bird lover.
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PD2R
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Posts: 131




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« Reply #8 on: February 19, 2009, 02:53:01 AM »

How about a vertical dipole strung along that fiber glass pole? No need for radials.
Do some testing and after that put it up as an inverted V. Do some more testing and find out what works best for you.

I personally have had good results with a vertical dipole on 20 meters during the last IOTA contest. We compared it to a ground mounted 1/4 wave vertical for the same band and it won hands down. I do have to mention that the antenna┬┤s were nearby salt water, 50 meter or so.

73, Maarten
PD2R
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WX4O
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Posts: 101




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« Reply #9 on: February 21, 2009, 11:08:36 PM »

I have a 5BTV, ground mounted with 16 frequency cut radials. I works very well on all bands. My house is located in a sort of valley, but it still works DX.
Also have 2 PAR Endfedz - one multibander and a single bander. They don't need radials, and are fairly short.
Universal sells 'em.
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