Re: Topband: Shortened Radial Experiments

[George Taft via Topband]

As a practical application, the "Battle Creek Special" is configured with 
shortened radicals; 30 X 60' for mni years now.   It's success is well known.
We found, that when 1/4 wvl radials were furnished, DXpeditions often did not 
have space for deployment.  And used only a few of the radials included.
73 George  W8UVZ 

On Thursday, October 26, 2017 10:53 PM, Mike Waters  
wrote:
 

 Elevated radials can also be run zigzag to fit them in the available space.
My 1/4 wavelength S radial was like that.

73, Mike
www.w0btu.com
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Re: Topband: Shortened Radial Experiments

[Michael Walker]

In my case I have lots of space and I can lay down radials or do elevated.

My vertical part is about 85ft and the rest is horizontal.  It has served
me well enough, but I honestly thing it could do much better and that is
why I ask.

My problem is I don't know how on this list truly knows what they are
talking about and who doesn't.  Therefore, I tend to review published
papers that have had some sort of peer review.

I do believe that 1/4 wave radials have excessive ground losses, which is
what I have now and it shows a very nice almost flat across the band.  We
know that is not the sign of an efficient antenna.  Yes, it shows about 37
ohms at its best, but there is more work to be done.

Mike
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Re: Topband: Shortened Radial Experiments

[Mike Waters]

Elevated radials can also be run zigzag to fit them in the available space.
My 1/4 wavelength S radial was like that.

73, Mike
www.w0btu.com
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Re: Topband: Shortened Radial Experiments

[k8...@alphacomm.net]

Jeez Carl,

If you had read my write-up, you would realize that I NEVER recommended 
2 radials for operatingjust as a simple technique to measure 
resonant radial length in one's soil


Also, the point is NOT that everyone should use shortened radials. The 
point IS that for hams with the typically 50' or so vertical portion of 
an inverted L, you can have good results without going to 120 radials 
that are 135 foot long!


However, I guess if you live next to the pond, results are much easier 
to come by. Those of us in the middle of the country don't have it quite 
so easy...


K8BHZ


On 10/26/2017 10:17 PM, Carl wrote:
My 300+ DXCC on 160 has not resorted to a shortened radial plus Im 
also past 100 DXCC with 5W amd 16 with 100 mw.


Some spend too much time thinking math is the only answer and miss a 
lot of DX.


Measuring 2 radials is a complete waste of time unless in a salt marsh 
as seasonal ground variations have huge variations. Even Beverage 
owners realize that and add radials to stabilize.


Carl




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Re: Topband: Shortened Radial Experiments

[Wes Stewart]

No need to do it on my account.

On 10/26/2017 6:31 AM, k8...@alphacomm.net wrote:
This issue does indeed keep coming up, so  I am posting my response (of 3 
years ago) again for K7EG, N7WS, VA3MVW, W0MU, and others.

 N7WS
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Re: Topband: Shortened Radial Experiments

[Michael Walker]

Thanks,

I need to digest this.

mike va3mw

On Thu, Oct 26, 2017 at 8:31 AM, k8...@alphacomm.net 
wrote:

> This issue does indeed keep coming up, so  I am posting my response (of 3
> years ago) again for K7EG, N7WS, VA3MVW, W0MU, and others. The shortened
> radials are still in use here, with 235 countries worked on 160.  The Vp
> shortening depends entirely on soil type, so math will only get you so
> close. Better to actually measure them in place, in your ground. Only two
> radials are necessary to do that.
>
> Brian  K8BHZ
>
> - Forwarded Message -
>
> From: k8...@hughes.net
> To: topband@contesting.com
> Sent: Friday, December 19, 2014 12:23:52 PM
> Subject: Topband: Fw: Shortened Radial Experiments
>
> From: Brian Mattson
> Sent: Saturday, October 14, 2006 7:56 PM
> To: topband@contesting.com
> Subject: Shortened Radial Experiments
>
> In response to Eddy's (VE3CUI) question about anyone using "shortened
> radials", I have been using these for two years now, with very good results.
>
> Coming to TopBand after decades on VHF, I was confused by the myriad of
> opinions on radials. Comments like "resonance disappears after a few buried
> radials" and "longer is better" were often seen. As a degreed electrical
> engineer, I was puzzled by the abandonment of the laws of physics once a
> radial was buried, or laid along the ground. Sure, the velocity factor &
> loss factors change significantly once a radial gets near, or below,
> ground, but basic electrical laws must still apply.
>
> As I first got on TopBand in the dead of winter, I used the single
> elevated radial as discussed in "Low Band DXing". Pointed towards Europe,
> and about 5 feet off the ground, it worked surprisingly well. However, when
> it came time to upgrade the ground system, confusion set in with all the
> conflicting opinions I read. Fortunately, I ran across Rudy Severns' (N6LF)
> article on "Verticals, Ground Systems and Some History" in QST (July 2000).
> ( As an electrical engineer in the switching power supply industry, I have
> learned to listen when Rudy speaks!). One comment that really caught my
> attention was on page 41: "For the 0.1 wavelength high (vertical) antenna,
> if we have a good ground screen out to a distance of 0.1 wavelength, we'll
> eliminate over 90% of the ground loss!". The lightbulb came on right then.
> I could instantly visualize an Electrostatics Fields class representation
> of a ground referenced hemispheric field intensity bubble with a radius of
> the vertical height. I use
>  a phased pair of inverted L's for my transmit antenna, and each has
> around 50 feet of vertical rise, so a system of enough 50 foot radials
> should suffice. But the nagging thought of resonant length still bothered
> me. Time to experiment (play).
>
> The inherent beauty of a quarter wavelength radial is in it's impedance
> transformation properties. Basically, the higher the impedance on one end,
> the lower the impedance on the other end. As the far end of the radial is
> open circuited, the antenna end is as low as possible, and it is
> non-reactive. Two opposing radial elements look suspiciously like a dipole,
> so that's where I began. All my measuring was done at 1.83 MHz, so a
> free-space dipole would be about 269 feet & have an impedance around 73
> ohms. All my experimenting was done with #14 solid insulated THHN copper
> wire.
>
> My first experiment was to construct a full size dipole and lay it on the
> ground. The resulting dipole was well below the lower operating frequency
> of the MFJ analyzer, so pruning was in order. I finally achieved resonance
> with a length of 182 feet! Rs was 130 ohms. So the velocity factor was
> thus: 182/269 = 0.677. So Eddy, don't take the 0.5 number from "Low Band
> DXing" as gospel, as it depends a lot on the type of soil you have. My soil
> is sandy (almost like beach sand). Note too that the ground proximity has
> increased Rs substantially. Next, I buried the dipole in a slit trench
> approximately 6" deep. Again, the dipole was way too long. To prune the
> buried dipole, I found it easiest to have the ends bent up so that they
> protrude just above ground & place a bright colored "wire nut" on the end
> (so I could find it again!). The resonant length of the dipole was now  107
> feet! Rs was 148 ohms. The buried velocity factor was: 107/269 = 0.398.
> Note that burying the dipole has add
>  ed even more losses to Rs.
>
> The result of experimenting thus far resulted in a resonant radial length
> (in my soil) of 53.5 feet (half of the dipole). With my 50 foot vertical
> inverted L's, I was ecstatic. But how many radials would I need?
>
> I constructed another buried dipole of 107 feet length, at right angles to
> the first, and so their centers were coincident. This gave me four radials.
> I tested the second dipole as a separate entity, and it's numbers were very
> close to the first. Next, I connected the two dipoles together (two
> 

Topband: Shortened Radial Experiments

[k8...@alphacomm.net]

This issue does indeed keep coming up, so  I am posting my response (of 
3 years ago) again for K7EG, N7WS, VA3MVW, W0MU, and others. The 
shortened radials are still in use here, with 235 countries worked on 
160.  The Vp shortening depends entirely on soil type, so math will only 
get you so close. Better to actually measure them in place, in your 
ground. Only two radials are necessary to do that.


Brian  K8BHZ

- Forwarded Message -

From: k8...@hughes.net
To: topband@contesting.com
Sent: Friday, December 19, 2014 12:23:52 PM
Subject: Topband: Fw: Shortened Radial Experiments

From: Brian Mattson
Sent: Saturday, October 14, 2006 7:56 PM
To: topband@contesting.com
Subject: Shortened Radial Experiments

In response to Eddy's (VE3CUI) question about anyone using "shortened radials", 
I have been using these for two years now, with very good results.

Coming to TopBand after decades on VHF, I was confused by the myriad of opinions on radials. Comments 
like "resonance disappears after a few buried radials" and "longer is better" were 
often seen. As a degreed electrical engineer, I was puzzled by the abandonment of the laws of physics 
once a radial was buried, or laid along the ground. Sure, the velocity factor & loss factors change 
significantly once a radial gets near, or below, ground, but basic electrical laws must still apply.

As I first got on TopBand in the dead of winter, I used the single elevated radial as discussed in "Low 
Band DXing". Pointed towards Europe, and about 5 feet off the ground, it worked surprisingly well. 
However, when it came time to upgrade the ground system, confusion set in with all the conflicting opinions I 
read. Fortunately, I ran across Rudy Severns' (N6LF) article on "Verticals, Ground Systems and Some 
History" in QST (July 2000). ( As an electrical engineer in the switching power supply industry, I have 
learned to listen when Rudy speaks!). One comment that really caught my attention was on page 41: "For 
the 0.1 wavelength high (vertical) antenna, if we have a good ground screen out to a distance of 0.1 
wavelength, we'll eliminate over 90% of the ground loss!". The lightbulb came on right then. I could 
instantly visualize an Electrostatics Fields class representation of a ground referenced hemispheric field 
intensity bubble with a radius of the vertical height. I use
 a phased pair of inverted L's for my transmit antenna, and each has around 50 
feet of vertical rise, so a system of enough 50 foot radials should suffice. 
But the nagging thought of resonant length still bothered me. Time to 
experiment (play).

The inherent beauty of a quarter wavelength radial is in it's impedance 
transformation properties. Basically, the higher the impedance on one end, the 
lower the impedance on the other end. As the far end of the radial is open 
circuited, the antenna end is as low as possible, and it is non-reactive. Two 
opposing radial elements look suspiciously like a dipole, so that's where I began. 
All my measuring was done at 1.83 MHz, so a free-space dipole would be about 269 
feet & have an impedance around 73 ohms. All my experimenting was done with #14 
solid insulated THHN copper wire.

My first experiment was to construct a full size dipole and lay it on the ground. The resulting dipole was 
well below the lower operating frequency of the MFJ analyzer, so pruning was in order. I finally achieved 
resonance with a length of 182 feet! Rs was 130 ohms. So the velocity factor was thus: 182/269 = 0.677. So 
Eddy, don't take the 0.5 number from "Low Band DXing" as gospel, as it depends a lot on the type 
of soil you have. My soil is sandy (almost like beach sand). Note too that the ground proximity has 
increased Rs substantially. Next, I buried the dipole in a slit trench approximately 6" deep. Again, 
the dipole was way too long. To prune the buried dipole, I found it easiest to have the ends bent up so that 
they protrude just above ground & place a bright colored "wire nut" on the end (so I could 
find it again!). The resonant length of the dipole was now  107 feet! Rs was 148 ohms. The buried velocity 
factor was: 107/269 = 0.398. Note that burying the dipole has add
 ed even more losses to Rs.

The result of experimenting thus far resulted in a resonant radial length (in 
my soil) of 53.5 feet (half of the dipole). With my 50 foot vertical inverted 
L's, I was ecstatic. But how many radials would I need?

I constructed another buried dipole of 107 feet length, at right angles to the first, and so their 
centers were coincident. This gave me four radials. I tested the second dipole as a separate 
entity, and it's numbers were very close to the first. Next, I connected the two dipoles together 
(two adjacent wires as one node/ the other two adjacent ones as the other). I was astounded when 
the resonant frequency plummeted!! I almost gave up at this point. As a VHFer, I knew that whether 
a ground plane has two or four radials shouldn't make much