EFHW

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Re: EFHW

K9MA
I'd have to total it up, but I probably made close to 1,000 contacts
with an  EFHW and KX1 last year.  The whole antenna system, including
the 38 foot fishing pole and tuner, weighs about 1.5 pounds.  Of course,
it doesn't work as well as a high, full-sized antenna, but if anyone can
come up with one that works better and doesn't weigh more, I'd like to
hear about it!

73,

Scott  K9MA

On 2/11/2017 23:19, Kevin - K4VD wrote:
> Or, for those of you that are thinking the situation isn't so hopeless,
> grab your portable antenna, head out to the campsite, throw your wire up in
> the tree and I'll catch you on the air. Let's warm up the worms.


--
Scott  K9MA

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Re: EFHW

Tony Estep
In reply to this post by Kevin - K4VD
On Sat, Feb 11, 2017 at 11:19 PM, Kevin - K4VD <[hidden email]> wrote:

> ...The end fed is only 10% efficient (did I get that right)...

==========
No, that's not right. The radiation pattern and gain of an end-fed halfwave
are little different from a center-fed dipole. The efficiency of an antenna
is not affected by feedpoint location. The end-fed antenna may be harder to
match than a center-fed, but that's a different question. If you have a
proper matching arrangement between the antenna's high impedance and your
feedline, you'll get results that are essentially identical to a standard
doublet. As I mentioned in an earlier post, two minutes with EZNEC will
clarify this.

"Efficiency" refers to the quotient of the antenna's radiation resistance,
divided by ohmic losses. If you have a short piece of wire, its radiation
resistance will be low, but for a half-wave wire it's 73 ohms, no matter
where it's fed.

As a side-note, I worked over 300 countries with a 100-foot wire strung out
my bedroom window (16 feet above the driveway) and running to a tree at the
end of the yard, 40 feet high at the far end. There's a picture of it on my
qrz.com page.

Tony KT0NY
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Re: EFHW

Wes Stewart-2
In reply to this post by Rick Dettinger-3
Alas, if only this was true.

Google "radial system design and efficiency in hf verticals" and you should get
a cached version of Rudy Severns' paper of the same name.  In it he states:

"Alternately we can graph efficiency in terms of Ga as shown in figures 3 and 4.
Unfortunately this also shows how inefficient verticals are even over very good
ground. Very depressing! For example, with very good soil (0.02/30) and 128
1/2-wave radials, the efficiency of a 1/4-wave vertical is still only -2.76 dB
(53%)!"

Wes  N7WS

On 2/11/2017 10:53 PM, Rick Dettinger wrote:
> It doesn’t take much effort to get to 50% efficient with a quarter wave or longer wire, and a few short radials.

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Re: EFHW

W3LPL
This post has NOT been accepted by the mailing list yet.
In reply to this post by Dan Presley
The core issue being discussed here is convenience/practicality of an EFHW antenna for portable/SOTA use vs. the efficiency of various feed systems and their assiciated radials or counterpoise.  Detailed analysis of the efficiency of various fixed site radial systems contributes little to answering Dan's initial query.  

A time honored technique to evaluate the efficiency of a single radiator is to install an RF ammeter in the antenna, ideally near the center of the EFHW radiator.   More efficient feed/radial/counterpoise systems will produce more RF current, and various alternatives can be readily evaluated

73
Frank
W3LPL
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Re: EFHW

Don Wilhelm
In reply to this post by Wes Stewart-2
Wes,

I do not doubt what you are saying about 1/2 wave verticals, but most
EFHW antennas are mounted as a sloper or a horizontal antenna.

For portable operation, the main concern is for the ability to feed the
antenna, and not about maximizing the far field strength.

73,
Don W3FPR

On 2/12/2017 12:34 PM, Wes Stewart wrote:

> Alas, if only this was true.
>
> Google "radial system design and efficiency in hf verticals" and you
> should get a cached version of Rudy Severns' paper of the same name.  In
> it he states:
>
> "Alternately we can graph efficiency in terms of Ga as shown in figures
> 3 and 4. Unfortunately this also shows how inefficient verticals are
> even over very good ground. Very depressing! For example, with very good
> soil (0.02/30) and 128 1/2-wave radials, the efficiency of a 1/4-wave
> vertical is still only -2.76 dB (53%)!"
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Re: EFHW

donovanf
Dan's original post concerned the effectiveness and practicality
of various EFHW configurations in a man pack environment.
Since he had already decided that his radiating element will
be 1/2 wavelength long, the primary concern is power transfer
efficiency vs. practicality of the solution in a weight and space
constrained man pack environment.


For the entire history of radio, RF ammeters have been used to
evaluate the efficiency of alternative matching systems and their
associated radial/counterpoise systems. An RF ammeter could
be placed in Dan's EFHW antenna -- ideally in the center -- to
compare the relative performance of practical man pack EFHW
implementations.


73
Frank
W3LPL


----- Original Message -----

From: "Don Wilhelm" <[hidden email]>
To: "Wes Stewart" <[hidden email]>, [hidden email]
Sent: Sunday, February 12, 2017 6:29:07 PM
Subject: Re: [Elecraft] EFHW

Wes,

I do not doubt what you are saying about 1/2 wave verticals, but most
EFHW antennas are mounted as a sloper or a horizontal antenna.

For portable operation, the main concern is for the ability to feed the
antenna, and not about maximizing the far field strength.

73,
Don W3FPR

On 2/12/2017 12:34 PM, Wes Stewart wrote:

> Alas, if only this was true.
>
> Google "radial system design and efficiency in hf verticals" and you
> should get a cached version of Rudy Severns' paper of the same name. In
> it he states:
>
> "Alternately we can graph efficiency in terms of Ga as shown in figures
> 3 and 4. Unfortunately this also shows how inefficient verticals are
> even over very good ground. Very depressing! For example, with very good
> soil (0.02/30) and 128 1/2-wave radials, the efficiency of a 1/4-wave
> vertical is still only -2.76 dB (53%)!"
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Re: EFHW

Wes Stewart-2
In reply to this post by Don Wilhelm
Don,

As I said earlier in this thread, if the radio is on the ground, or near the
ground, then the antenna is a vertical.  I don't care what the slope is, it has
a vertical component.  A Beverage is a horizontal wire, but it is vertically
polarized and works against ground.  It may be lousy ground (which is actually
required) but nevertheless there is a connection to earth.

I think the fallacy here is that folks believe that a 1/4 wave wire, which
wouldn't have such an intractable feedpoint impedance, requires "ground" and an
EFHW doesn't.

Now if the battery-powered radio is dangling above the earth at the end of a
horizontal wire and the keying is via Bluetooth I guess there is some ground
independence.  But in that case I would recommend putting the radio in the
middle of the wire and saving some grief.  Likewise, if you want to fool with a
Zepp feed why not use center feed?

If maximizing far field strength is of no concern then I recommend a 50 Ohm load
on the output of the radio :-)  You could crank the power down to save the
battery and it would have no effect whatsoever on the signal strength at the
receiving end.  A win-win!

Wes  N7WS

2/12/2017 11:29 AM, Don Wilhelm wrote:

> Wes,
>
> I do not doubt what you are saying about 1/2 wave verticals, but most EFHW
> antennas are mounted as a sloper or a horizontal antenna.
>
> For portable operation, the main concern is for the ability to feed the
> antenna, and not about maximizing the far field strength.
>
> 73,
> Don W3FPR
>
> On 2/12/2017 12:34 PM, Wes Stewart wrote:
>> Alas, if only this was true.
>>
>> Google "radial system design and efficiency in hf verticals" and you
>> should get a cached version of Rudy Severns' paper of the same name.  In
>> it he states:
>>
>> "Alternately we can graph efficiency in terms of Ga as shown in figures
>> 3 and 4. Unfortunately this also shows how inefficient verticals are
>> even over very good ground. Very depressing! For example, with very good
>> soil (0.02/30) and 128 1/2-wave radials, the efficiency of a 1/4-wave
>> vertical is still only -2.76 dB (53%)!"
>

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Re: EFHW

Lynn W. Taylor, WB6UUT
In reply to this post by Kevin - K4VD
How about "All the local and DX QSOs with a random wire were not made
with and end fed HALF-WAVE."

On 2/11/2017 9:19 PM, Kevin - K4VD wrote:
> So what we are saying here is that all the local and DX QSOs we make from
> a picnic bench with an end fed or random wire thrown up in a tree and a
> short or no counterpoise doesn't really happen or, at best, is a fluke.

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Re: EFHW

K9MA
In reply to this post by Wes Stewart-2
I think what this thread is about is effective, very lightweight
antennas for backpacking, SOTA, bicycle touring, etc.  These are
antennas that, not including the support, weigh just a few ounces.
Whether they could be made to work better with hundreds of long radials
is completely irrelevant.

Without question, the EFHW minimizes resistive losses due to the high
feedpoint impedance, and eliminates the need for a feedline. If you
model a typical antenna of this sort, say a 66 foot wire with a single
38 foot support, and move the feedpoint around, you will find very
little difference in the far field.  End fed is within a fraction of a
dB of center fed, and requires no feedline.  Even 38 feet of RG-174
would weigh much more than a simple EFHW tuner, and the coax loss would
be about 1 dB on 20.  Now, one could make some ladder line with some
number 26 wire and spacers, but imagine trying to get that untangled
every time you put up the antenna.  (Another consideration:  These
antennas should be quick and easy to put up.)

As I said, if anyone knows how to make a better, lighter antenna, let me
know!

An aside:  There are two major loss components when feeding any antenna
near ground.  One is due to the resistance which appears in series with
the feedpoint. (I'll call this the feedpoint loss.)  The extreme example
is a short vertical fed against ground, where the effective resistance
of the connection to ground is large compared to the feedpoint
resistance.  Raising the feedpoint resistance will reduce this loss, the
other extreme being the EFHW.  The other source of loss is the
interaction of the electromagnetic field of the antenna with the ground
within some fraction of a wavelength from the antenna.  Even a vertical
EFHW, with very low feedpoint loss, needs lots of long radials to
minimize this loss.  Ideally, you want to minimize both sources of
loss.  If a big radial system isn't feasible, it still helps to minimize
the feedpoint loss.

73,

Scott  K9MA

--
Scott  K9MA

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Re: EFHW

Igor Sokolov-2
In reply to this post by Wes Stewart-2
" if the radio is on the ground, or near the ground, then the antenna is
a vertical."
Wes  N7WS

Does this statement actually mean that  horizontally polarized antennas
do not exist for those, whose radio is not high enough above the ground. :)

73, Igor UA9CDC


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Re: EFHW

Jim Brown-10
In reply to this post by Kevin - K4VD
On Sat,2/11/2017 9:19 PM, Kevin - K4VD wrote:
> ​So what we are saying here is that all the local and DX QSOs we make from
> a picnic bench with an end fed or random wire thrown up in a tree and a
> short or no counterpoise doesn't really happen or, at best, is a fluke.

Not at all -- but the fact is that running QRP into poor antennas is the
equivalent of having both hands tied behind your back. If that pops your
cork, great. FWIW, I've worked 165 with 5w in about four years. But I
have great antennas.

73, Jim K9YC

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Re: EFHW

Wes Stewart-2
In reply to this post by Igor Sokolov-2
This thread is a long one and frankly I didn't follow it at first, but a little
research says that the OP was interested in bringing a coax feeder directly into
the radio from the end of a wire.  He incorrectly called the coax a
"counterpoise", instead of an extension of the wire which it really is, because
it's going to radiate, but never mind that.  In this case, the antenna is a
"sloper" whether it is called that or not.  If one end is higher than the TX
then there is a vertical component to the geometry and the radio chassis is the
"counterpoise." :-)

73, Wes  N7WS

On 2/12/2017 4:22 PM, Igor Sokolov wrote:
> " if the radio is on the ground, or near the ground, then the antenna is a
> vertical."
> Wes  N7WS
>
> Does this statement actually mean that  horizontally polarized antennas do not
> exist for those, whose radio is not high enough above the ground. :)
>
> 73, Igor UA9CDC

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Re: EFHW

Jim Brown-10
In reply to this post by Rick Dettinger-3
Not true, Ron. Most AM broadcast transmitting antennas are in the range
of 80-90 electrical degrees (a quarter wave).  Nearly all of the Class I
clear channel stations use antennas that are at least 180 electrical
degrees. You can see this data for any US station at

https://www.fcc.gov/media/radio/am-query

WLW's tower is 189.3 degrees.  So is WLS.  WGN is 195 degrees. WBZ uses
an array of four towers that are 188.5 degrees.  WIND on 560 kHz near
Chicago, has an array of four 100 degree towers. The station where I
worked in my home town has an array of four 82 degree towers.  And so on.

73, Jim K9YC

On Sun,2/12/2017 9:13 AM, Ron D'Eau Claire wrote:
> Most BCB (0.5 to 1.6 MHz) antennas are 1/8 wavelength high (or less) which necessitates an extensive ground system.


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Re: EFHW

k6dgw
KFBK in Sacramento uses [or used, my info is a few years old] a
center-fed half-wave vertical ["Franklin"] antenna, said to be the only
one left.  It's ... interesting. [:-)  KFBK is also the originator of
the first out-phasing BC TX which became the RCA Ampliphase [or
Amplifuzz if you ever had to get one to pass PoP].  KFBK is also the
radio birthplace of Rush, "Bloviator in Chief," although that's probably
far less important than the Franklin.  There was a radial field under
the Franklin, it may have rusted into oblivion by now, I'm not sure it
was all that important, it's located in the flood plain north of
Sacramento ... moderately wet, they grow rice in the area.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 2/12/2017 5:31 PM, Jim Brown wrote:

> Not true, Ron. Most AM broadcast transmitting antennas are in the
> range of 80-90 electrical degrees (a quarter wave).  Nearly all of the
> Class I clear channel stations use antennas that are at least 180
> electrical degrees. You can see this data for any US station at
>
> https://www.fcc.gov/media/radio/am-query
>
> WLW's tower is 189.3 degrees.  So is WLS.  WGN is 195 degrees. WBZ
> uses an array of four towers that are 188.5 degrees.  WIND on 560 kHz
> near Chicago, has an array of four 100 degree towers. The station
> where I worked in my home town has an array of four 82 degree towers.  
> And so on.
>
> 73, Jim K9YC
>
> On Sun,2/12/2017 9:13 AM, Ron D'Eau Claire wrote:
>> Most BCB (0.5 to 1.6 MHz) antennas are 1/8 wavelength high (or less)
>> which necessitates an extensive ground system.
>
>
> ______________________________________________________________
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>

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Re: EFHW

donovanf
There are excellent photos and a description of the KFBK Franklin array here:



https://www.fybush.com/sites/2005/site-051028.html 


73
Frank
W3LPL

----- Original Message -----

From: "Fred Jensen" <[hidden email]>
To: [hidden email]
Sent: Monday, February 13, 2017 3:56:33 AM
Subject: Re: [Elecraft] EFHW

KFBK in Sacramento uses [or used, my info is a few years old] a
center-fed half-wave vertical ["Franklin"] antenna, said to be the only
one left. It's ... interesting. [:-) KFBK is also the originator of
the first out-phasing BC TX which became the RCA Ampliphase [or
Amplifuzz if you ever had to get one to pass PoP]. KFBK is also the
radio birthplace of Rush, "Bloviator in Chief," although that's probably
far less important than the Franklin. There was a radial field under
the Franklin, it may have rusted into oblivion by now, I'm not sure it
was all that important, it's located in the flood plain north of
Sacramento ... moderately wet, they grow rice in the area.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 2/12/2017 5:31 PM, Jim Brown wrote:

> Not true, Ron. Most AM broadcast transmitting antennas are in the
> range of 80-90 electrical degrees (a quarter wave). Nearly all of the
> Class I clear channel stations use antennas that are at least 180
> electrical degrees. You can see this data for any US station at
>
> https://www.fcc.gov/media/radio/am-query 
>
> WLW's tower is 189.3 degrees. So is WLS. WGN is 195 degrees. WBZ
> uses an array of four towers that are 188.5 degrees. WIND on 560 kHz
> near Chicago, has an array of four 100 degree towers. The station
> where I worked in my home town has an array of four 82 degree towers.
> And so on.
>
> 73, Jim K9YC
>
> On Sun,2/12/2017 9:13 AM, Ron D'Eau Claire wrote:
>> Most BCB (0.5 to 1.6 MHz) antennas are 1/8 wavelength high (or less)
>> which necessitates an extensive ground system.
>
>
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft 
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net 
> Please help support this email list: http://www.qsl.net/donate.html 
> Message delivered to [hidden email]
>

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Re: EFHW

Ken K6MR
Yep, flamethrower of No. Cal.  The groundwave coverage is amazing.

Imagine how big that thing would be if they were on 580 instead of 1530  :^)

Ken K6MR


From: [hidden email]<mailto:[hidden email]>
Sent: Sunday, February 12, 2017 9:07 PM
To: [hidden email]<mailto:[hidden email]>
Subject: Re: [Elecraft] EFHW

There are excellent photos and a description of the KFBK Franklin array here:



https://www.fybush.com/sites/2005/site-051028.html


73
Frank
W3LPL

----- Original Message -----

From: "Fred Jensen" <[hidden email]>
To: [hidden email]
Sent: Monday, February 13, 2017 3:56:33 AM
Subject: Re: [Elecraft] EFHW

KFBK in Sacramento uses [or used, my info is a few years old] a
center-fed half-wave vertical ["Franklin"] antenna, said to be the only
one left. It's ... interesting. [:-) KFBK is also the originator of
the first out-phasing BC TX which became the RCA Ampliphase [or
Amplifuzz if you ever had to get one to pass PoP]. KFBK is also the
radio birthplace of Rush, "Bloviator in Chief," although that's probably
far less important than the Franklin. There was a radial field under
the Franklin, it may have rusted into oblivion by now, I'm not sure it
was all that important, it's located in the flood plain north of
Sacramento ... moderately wet, they grow rice in the area.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 2/12/2017 5:31 PM, Jim Brown wrote:

> Not true, Ron. Most AM broadcast transmitting antennas are in the
> range of 80-90 electrical degrees (a quarter wave). Nearly all of the
> Class I clear channel stations use antennas that are at least 180
> electrical degrees. You can see this data for any US station at
>
> https://www.fcc.gov/media/radio/am-query
>
> WLW's tower is 189.3 degrees. So is WLS. WGN is 195 degrees. WBZ
> uses an array of four towers that are 188.5 degrees. WIND on 560 kHz
> near Chicago, has an array of four 100 degree towers. The station
> where I worked in my home town has an array of four 82 degree towers.
> And so on.
>
> 73, Jim K9YC
>
> On Sun,2/12/2017 9:13 AM, Ron D'Eau Claire wrote:
>> Most BCB (0.5 to 1.6 MHz) antennas are 1/8 wavelength high (or less)
>> which necessitates an extensive ground system.
>
>
> ______________________________________________________________
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Re: EFHW

Dr. William J. Schmidt, II
Or. imagine using it in a 160 contest...


Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ
 
Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois
 
Owner – Operator
Villa Grand Piton - J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com

email:  [hidden email]
 

> On Feb 12, 2017, at 11:29 PM, Ken K6MR <[hidden email]> wrote:
>
> Yep, flamethrower of No. Cal.  The groundwave coverage is amazing.
>
> Imagine how big that thing would be if they were on 580 instead of 1530  :^)
>
> Ken K6MR
>
>
> From: [hidden email]<mailto:[hidden email]>
> Sent: Sunday, February 12, 2017 9:07 PM
> To: [hidden email]<mailto:[hidden email]>
> Subject: Re: [Elecraft] EFHW
>
> There are excellent photos and a description of the KFBK Franklin array here:
>
>
>
> https://www.fybush.com/sites/2005/site-051028.html
>
>
> 73
> Frank
> W3LPL
>
> ----- Original Message -----
>
> From: "Fred Jensen" <[hidden email]>
> To: [hidden email]
> Sent: Monday, February 13, 2017 3:56:33 AM
> Subject: Re: [Elecraft] EFHW
>
> KFBK in Sacramento uses [or used, my info is a few years old] a
> center-fed half-wave vertical ["Franklin"] antenna, said to be the only
> one left. It's ... interesting. [:-) KFBK is also the originator of
> the first out-phasing BC TX which became the RCA Ampliphase [or
> Amplifuzz if you ever had to get one to pass PoP]. KFBK is also the
> radio birthplace of Rush, "Bloviator in Chief," although that's probably
> far less important than the Franklin. There was a radial field under
> the Franklin, it may have rusted into oblivion by now, I'm not sure it
> was all that important, it's located in the flood plain north of
> Sacramento ... moderately wet, they grow rice in the area.
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Re: EFHW

Wes Stewart-2
In reply to this post by k6dgw
 From the WWV site:

The WWV antennas are half-wave vertical antennas that radiate omnidirectional
patterns. There are actually five antennas at the station site, one for each
frequency. Each antenna is connected to a single transmitter using a rigid
coaxial line, and the site is designed so that no two coaxial lines cross. Each
antenna is mounted on a tower that is approximately one half-wavelength tall.
The tallest tower, for 2.5 MHz, is about 60 m tall. The shortest tower, for 20
MHz, is about 7.5 m tall. The top half of each antenna is a quarter-wavelength
radiating element. The bottom half of each antenna consists of nine
quarter-wavelength wires that connect to the center of the tower and slope
downwards to the ground at a 45 degree angle. This sloping skirt functions as
the lower half of the radiating system and also guys the antenna

As a side note, several years ago when my late wife and I were still traveling
around in an RV we were near Ft. Collins.  As I have done with other stations I
telephoned the site and asked whether I could get a tour.  The NIST guy was
incredulous and said that no way did they give tours.  I said, pity, I'm an
engineer and ham and am disappointed.  He thought for moment and then said,
"Actually, we have a contractor doing some work here and the gate is unlocked.  
If you were to drive in and look around you wouldn't be bothered, but please
stay in your car."  So we did.  The WWVB antenna was pretty impressive, but
nothing like NAA in Cutler, Maine.

Wes  N7WS


On 2/12/2017 8:56 PM, Fred Jensen wrote:

> KFBK in Sacramento uses [or used, my info is a few years old] a center-fed
> half-wave vertical ["Franklin"] antenna, said to be the only one left.  It's
> ... interesting. [:-)  KFBK is also the originator of the first out-phasing BC
> TX which became the RCA Ampliphase [or Amplifuzz if you ever had to get one to
> pass PoP].  KFBK is also the radio birthplace of Rush, "Bloviator in Chief,"
> although that's probably far less important than the Franklin.  There was a
> radial field under the Franklin, it may have rusted into oblivion by now, I'm
> not sure it was all that important, it's located in the flood plain north of
> Sacramento ... moderately wet, they grow rice in the area.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County

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Re: EFHW

Guy Olinger K2AV
In reply to this post by Don Wilhelm
On the low bands most end fed half waves are inverted L's or fairly close
and for very good reason.  That's due to the kind of support people
commonly have for an 80 meter wire that's a total of 135 feet long.

Most commonly, a pair of trees, a horizontal wire between them, and at one
end of it connected to a wire dropping vertically to the ground plus some
kind of matching network at the ground or elevated counterpoise. The only
weight is the aerial wire itself, no heavy baluns or coax in the air to rob
the "L" of height.

73, Guy K2AV

On Sun, Feb 12, 2017 at 1:29 PM, Don Wilhelm <[hidden email]> wrote:

> Wes,
>
> I do not doubt what you are saying about 1/2 wave verticals, but most EFHW
> antennas are mounted as a sloper or a horizontal antenna.
>
> For portable operation, the main concern is for the ability to feed the
> antenna, and not about maximizing the far field strength.
>
> 73,
> Don W3FPR
>
> On 2/12/2017 12:34 PM, Wes Stewart wrote:
>
>> Alas, if only this was true.
>>
>> Google "radial system design and efficiency in hf verticals" and you
>> should get a cached version of Rudy Severns' paper of the same name.  In
>> it he states:
>>
>> "Alternately we can graph efficiency in terms of Ga as shown in figures
>> 3 and 4. Unfortunately this also shows how inefficient verticals are
>> even over very good ground. Very depressing! For example, with very good
>> soil (0.02/30) and 128 1/2-wave radials, the efficiency of a 1/4-wave
>> vertical is still only -2.76 dB (53%)!"
>>
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Re: EFHW

donovanf
In reply to this post by Wes Stewart-2
Hi Wes,


The WWV half wave vertical is much like the "Happy Accident
Ground Plane" described in January 1957 QST that uses only four
sloping radials, sloped downward 30 degrees to produce direct
50 ohm feed point impedance. The sloped radials make them into
radiators, hence the feed point impedance is raised to 50 ohms with
the appropriate slope.



The feed points of the WWV antennas are 1/4 wavelength high, but
I'm sure the performance would be little affected by lowering it
somewhat.


This antenna isn't quite a balanced half wave vertical, it isn't quite
a ground plane, and it isn't quite a sleeve dipole but it definitely
works very, very well.


I used a 20 meter "Happy Accident Ground Plane" mounted 50 feet

up in a maple tree for many years when I was in Rhode Island during
the 1960s and worked the world with it.


73
Frank
W3LPL

----- Original Message -----

From: "Wes Stewart" <[hidden email]>
To: [hidden email]
Sent: Monday, February 13, 2017 6:43:29 AM
Subject: Re: [Elecraft] EFHW

From the WWV site:

The WWV antennas are half-wave vertical antennas that radiate omnidirectional
patterns. There are actually five antennas at the station site, one for each
frequency. Each antenna is connected to a single transmitter using a rigid
coaxial line, and the site is designed so that no two coaxial lines cross. Each
antenna is mounted on a tower that is approximately one half-wavelength tall.
The tallest tower, for 2.5 MHz, is about 60 m tall. The shortest tower, for 20
MHz, is about 7.5 m tall. The top half of each antenna is a quarter-wavelength
radiating element. The bottom half of each antenna consists of nine
quarter-wavelength wires that connect to the center of the tower and slope
downwards to the ground at a 45 degree angle. This sloping skirt functions as
the lower half of the radiating system and also guys the antenna

As a side note, several years ago when my late wife and I were still traveling
around in an RV we were near Ft. Collins. As I have done with other stations I
telephoned the site and asked whether I could get a tour. The NIST guy was
incredulous and said that no way did they give tours. I said, pity, I'm an
engineer and ham and am disappointed. He thought for moment and then said,
"Actually, we have a contractor doing some work here and the gate is unlocked.
If you were to drive in and look around you wouldn't be bothered, but please
stay in your car." So we did. The WWVB antenna was pretty impressive, but
nothing like NAA in Cutler, Maine.

Wes N7WS


On 2/12/2017 8:56 PM, Fred Jensen wrote:

> KFBK in Sacramento uses [or used, my info is a few years old] a center-fed
> half-wave vertical ["Franklin"] antenna, said to be the only one left. It's
> ... interesting. [:-) KFBK is also the originator of the first out-phasing BC
> TX which became the RCA Ampliphase [or Amplifuzz if you ever had to get one to
> pass PoP]. KFBK is also the radio birthplace of Rush, "Bloviator in Chief,"
> although that's probably far less important than the Franklin. There was a
> radial field under the Franklin, it may have rusted into oblivion by now, I'm
> not sure it was all that important, it's located in the flood plain north of
> Sacramento ... moderately wet, they grow rice in the area.
>
> 73,
>
> Fred ["Skip"] K6DGW
> Sparks NV DM09dn
> Washoe County

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