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Author Topic: Vertical antenna-how is this possible?  (Read 6550 times)
AF5CC
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Posts: 1000




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« on: March 13, 2014, 11:49:12 AM »

I was on an antenna manufacturer's website today (not MFJ or one of their associated companies) and here is what they had to say about their quarter wave vertical antennas:

" These verticals require only a modest earth ground system.  Complex ground and radial systems are optional, but extensive installation experience has proven that outstanding performance is achieve with only a simple mounting post which doubles as the ground rod."

Now how is this possible?  Seems they have violated the laws of physics, unless the simple mounting post is in the middle of the ocean. 
Guess it depends on how you define outstanding performance.

John AF5CC
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K5RT
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Posts: 161




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« Reply #1 on: March 13, 2014, 12:01:31 PM »

"outstanding performance" as compared to what?

Paul
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W1JKA
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Posts: 1812




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« Reply #2 on: March 13, 2014, 12:33:36 PM »

  Sounds just like another run of the mill antenna manufacturer that specializes in selling the
sizzle and not the steak.
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WB6BYU
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Posts: 13467




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« Reply #3 on: March 13, 2014, 01:45:09 PM »

"Outstanding performance" in terms of low SWR over a wide bandwidth perhaps.
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AB4ZT
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Posts: 177




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« Reply #4 on: March 13, 2014, 02:18:27 PM »

I searched every major vertical maker's web site to try and find who was peddling this nonsense.  I kept coming up empty until I found it in a place I would not expect: Mosley.  I love my decades-old TA-33 yagi, but this was disappointing.

73,

Richard, AB4ZT
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KJ3N
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« Reply #5 on: March 13, 2014, 03:02:27 PM »

"outstanding performance" as compared to what?

A dummy load?
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WS3N
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Posts: 770




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« Reply #6 on: March 13, 2014, 03:10:49 PM »

I searched every major vertical maker's web site to try and find who was peddling this nonsense.  I kept coming up empty until I found it in a place I would not expect: Mosley.  I love my decades-old TA-33 yagi, but this was disappointing.

73,

Richard, AB4ZT

Paste the first sentence into Google. It's at the top.
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AF5CC
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Posts: 1000




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« Reply #7 on: March 13, 2014, 07:01:05 PM »

"Outstanding performance" in terms of low SWR over a wide bandwidth perhaps.

My dummy load does that and it is made my MFJ.

John AF5CC
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G8HQP
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Posts: 125




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« Reply #8 on: March 14, 2014, 08:49:32 AM »

No violation of physics needed. Just use the coax outer as an 'informal' counterpoise, with unfortunate resonances somewhat damped by a rather resistive ground connection at the base of the antenna. At least this is one step up from using the coax as the main antenna element!
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W5LZ
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Posts: 477




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« Reply #9 on: March 14, 2014, 09:13:34 AM »

Got the feeling that 'something ain't right' about these 'miracle antennas'?  You're right.  The next step is to figure out where that 'not right' part is getting into it, some mysterious physics, advertising, or just not enough information being given as to the 'why' of it.  Unfortunately, in most cases, it's a combination of advertising and not enough information, and that's getting more common as time goes on.
Compared to no antenna, almost anything can be called 'outstanding'.  That certainly doesn't mean it is even 'satisfactory', or better than a dummy load, you know?  Nothing 'new' in that (other than a 'name-brand' making those claims?), been done for years.  The solution is to have more information about the antenna, how it's set up, etc...
 - Paul
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K8AG
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Posts: 352




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« Reply #10 on: March 14, 2014, 09:26:36 AM »

"outstanding performance" as compared to what?

Paul
A dummy load, obviously. Roll Eyes
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W8JI
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« Reply #11 on: March 14, 2014, 10:03:45 AM »

The Mosley vertical, without any radials, is still better than a CHA250 Comet with 100 radials or an Isotron antenna. Look at the eHam reviews for those things!

People think anything that makes contacts is great!
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W5WSS
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« Reply #12 on: March 14, 2014, 12:50:34 PM »

An outstanding Marconi relative to less than outstanding Marconi's.
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W3HKK
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« Reply #13 on: March 14, 2014, 01:55:37 PM »

Ive  used many a quickie vertical or  inverted L  with  wire taped to a  fiberglas cheapie fishing pole, taped to a  ground rod, direct fed by coax.  Or  on 160m - 130 ft of wire thrown over a tree fed against a ground rod, and was delighted with the results.  So you can be very pleased with the results and surprisingly  low swr, at least here in the Midwest where the ground conductivity is  decent.

So Id chalk it up to advertising exhuberance. 
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ZENKI
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Posts: 980




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« Reply #14 on: March 14, 2014, 03:39:48 PM »

Maybe you get a coupon with the antenna so you can move to  location with better ground conductivity or somewhere near seawater.

Ground conductivity and Brewster takeoff angle determines vertical antenna performance not what the manufacturer claims. I have yet to find  a manufacturer who can put a good ground system in a packet or a box.

Having said that many of the so called "no radial/ground/ verticals like the Hygain AV640 etc if place high like 30ft or more above the ground can be  very good performers.
At a contest station  that I operated from we had 1/4 wave verticals up very high. Anywhere from 100 to 200ft and sometimes you could not tell the difference from  using the stacked yagis and a simple vertical. When you get away from lossy ground vertical start to work very well. Ground loss will always dominate over other design losses unless you using one  of these fraudulent magic pudding antennas.
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