Sorry, Jim, you are misquoting the wrong guy. Tweren't me, McGee.
73 Jim Allen W6OGC
> Message: 24
> Date: Fri, 30 Dec 2016 13:25:28 -0800
> From: Jim Brown <j...@audiosystemsgroup.com>
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] Small QRP antenna
> Message
Sorry Jim, you're mistaken on many counts.
An antenna does not have VF, but the wire we use for it does. VF of an
infinitely thin bare wire in free space is 1. Surrounding it with a
dielectric (insulation) makes it longer electrically, usually by a few
percent. So does making the wire
My experience matches this precisely.
~35 years ago, I built the huge quad described in "Evolution of a Quad Array"
from an article in QST, May 1978, IIRC. It was done with help from experienced
antenna builders, measured very meticulously. When we finally got it up on the
tower, it was
On Thu,12/29/2016 3:07 PM, Bill Johnson wrote:
Having "only" 5 watts doesn't change the need for proper termination and
antenna match.
By proper termination, I think you're thinking about SWR and a match to
the transmitter. This thread is several days and 20+ posts old, but I
think I
You aren't being overly pedantic ... you're simply being wrong. Velocity
factor for electromagnetic emmissions is the ratio of any signal in any
environment compared to its value in free space. The velocity factor of
a signal in a transmission line is a function of geometry and
surrounding
Not so.
On 12/29/2016 4:33 PM, Walter Underwood wrote:
This is quite likely overly pedantic, but “velocity factor” is a characteristic
of transmission lines. Interestingly, it is independent of frequency (up to the
limit of the dielectric).
Walt,
I differ, antenna wires do have a velocity factor to consider. I built
a 6 meter Moxon beam for my grandson out of insulated wire, and the
resonant frequency was considerably low. Stripping the insulation from
the wire brought its resonance point up to what was expected.
The only
This is quite likely overly pedantic, but “velocity factor” is a characteristic
of transmission lines. Interestingly, it is independent of frequency (up to the
limit of the dielectric). It depends on the geometry of the line and the
dielectric material.
Antennas don’t have a velocity factor.
I've stayed out of this discussion so far.
I can comment on building a J-pole for 10m and 6m. I used a 24-foot
tall 1-inch diameter aluminum mast held by a 8-foot section of
Rohn-25G "planted" in the ground (no concrete). I used 1/4 wave stub
space 2-inch running parallel to the mast from
craft-boun...@mailman.qth.net] On Behalf Of Jim
Brown
Sent: Thursday, December 29, 2016 12:59 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna
Nothing in this post is true. Optimum length for a counterpoise is a quarter
wave. Radials are a form of counterpoise, and their optimum leng
and I think his
knowledge and writing skill has improved with age!
73,
Bill
K9YEQ
-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Mike
Morrow
Sent: Thursday, December 29, 2016 12:09 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP
Except for what I'm about to say, what Jim says in his first sentence is true,
which of course includes his post:-)
The velocity of propagation in a wire, near to, on, or below the ground is
different from the same wire in free space. How different? Most people don't
know, don't care or
Fred,
You summed up antennas in general very well, and especially end fed dipoles.
I would like to add a bit to your item 7 - dealing with the matching of
a half wave end fed to a 50 ohm line - and the counterpoise wire.
There are two common ways of matching to an end fed half wave. One is
On Thu,12/29/2016 1:53 PM, Bill Frantz wrote:
If this is really what is going on, then a bit longer than 1/8 wave
should be about right for radials on/under the ground.
I did an NEC study several years ago placing a half wave dipole at
heights above ground from several feet down to an inch,
Ground rods are pretty ineffective at RF, Dick although I'm not
surprised your Inv-L works good. It all depends on the quality of the
"earth" around your antenna. If yours is good, you're fortunate.
Saltwater is great. Keep in mind that you're trying to provide a return
for an
I may be seriously wrong, but shorter than 1/4 wave ground
mounted radials are probably affected by the same ground tuning
effects that allow a Beverage on the Ground antenna to be
considerably shorter than one mounted above the ground. If this
is really what is going on, then a bit longer
I'm fairly certain that Fred meant 1/2 wave ... correct hand, wrong
finger, happens to me all the time.
This has been going on for a long time, here's a summary and maybe it
can rest for awhile:
1. Elecraft ATU's are L-networks. Theoretically, one of the 4 L-net
configurations will match
Sorry Fred, I replied to what you wrote, not what you thought. Sometimes
my mind-reading skills fail me. :) I agree with your comments in the
context of an end-fed half wave radiator. I modeled this in NEC several
years ago. The result suggested a dB or so for a full radial system with
a half
Jim, almost everyone on the list immediately noticed that I
accidentally typed 1/4 when I actually meant to type 1/2. They most
likely noticed it because the thread has been almost 100% about 1/2 end
fed radiators. The person I replied to specifically asked about adding
a 1/4 wave counterpoise
s a radiator ground plane. ..
>>> The. ..G0MVP.
>>>
>>> mjis...@btinternet.com
>>>
>>>
>>> Sent from Samsung Mobile
>>>
>>>
>>> Original message
>>> From: Fred Moore
>>> Date:29/12
This slides for a talk I've done at Pacificon and for several ham clubs
will tell you everything you need to know about it!
http://audiosystemsgroup.com/160MPacificon.pdf
73, Jim K9YC
On Thu,12/29/2016 8:49 AM, Richard Fjeld wrote:
With reference to below, I have a question please. I put up
Nothing in this post is true. Optimum length for a counterpoise is a
quarter wave. Radials are a form of counterpoise, and their optimum
length is also a quarter wave. More radials reduce ground losses.
Failing to provide an adequate counterpoise will cause the antenna's
return current to flow
;elecraft@mailman.qth.net>
Sent: Thursday, December 29, 2016 9:05 AM
Subject: Re: [Elecraft] Small QRP antenna
Dick,
With buried radials, they do not have to be 1/4 wave long, and a single
one will probably not make much difference over your ground rod.
What you want to accomplish is a
Don wrote:
> A 1/2 wave radiator fed at the end theoretically does not need
> any counterpoise, but in practice it does - but only needs to
> be about 0.05 wavelength long.
>
> Refer to some antenna books (the ARRL has a good one) or the ARRL
> Handbook for good information about basic antennas.
Dick,
With buried radials, they do not have to be 1/4 wave long, and a single
one will probably not make much difference over your ground rod.
What you want to accomplish is a "ground screen", which means many short
(about 1/8 wavelength) close to the base of the radiator and a few
extending
he. ..G0MVP.
>>>
>>> mjis...@btinternet.com
>>>
>>>
>>> Sent from Samsung Mobile
>>>
>>>
>>> Original message
>>> From: Fred Moore
>>> Date:29/12/2016 13:04 (GMT+00:00)
>>> To: elecraft@
ung Mobile
Original message
From: Fred Moore
Date:29/12/2016 13:04 (GMT+00:00)
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna
Don,
Thank you very much, for pointing out a very common issue that gets
mixed up into discussions. Your point is so valid the random w
use a quarter
>> wave length of counter point as a radiator ground plane. ..
>> The. ..G0MVP.
>>
>> mjis...@btinternet.com
>>
>>
>> Sent from Samsung Mobile
>>
>>
>> Original message --------
>> From: Fred Moor
e:29/12/2016 13:04 (GMT+00:00)
> To: elecraft@mailman.qth.net
> Subject: Re: [Elecraft] Small QRP antenna
>
> Don,
>
> Thank you very much, for pointing out a very common issue that gets
> mixed up into discussions. Your point is so valid the random wire
> always seems to get mix
...@btinternet.com
Sent from Samsung Mobile
Original message From: Fred Moore
<f...@fmeco.com> Date:29/12/2016 13:04 (GMT+00:00) To:
elecraft@mailman.qth.net Subject: Re: [Elecraft] Small QRP antenna
Don,
Thank you very much, for pointing out a very common issue that gets
mi
Don,
Thank you very much, for pointing out a very common issue that gets
mixed up into discussions. Your point is so valid the random wire
always seems to get mixed into the 1/2 wave discussion for some
reason.. and should never be mixed together. you are absolutely
correct.. thanks again
Scott,
If the radiator is not a half wave long, it is not a "half wave".
Yes, a random length wire may work, but please do not call a random
length a half wave - the length of a half wave is quite specific.
Similarly, a quarter wavelength is a specific length at a particular
frequency.
73,
ave long thrown on the
ground is
adequate.
I too have had excellent results with them.
73 Ron AC7AC
-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of
Fred
Jensen
Sent: Wednesday, December 28, 2016 12:57 PM
To: elecraft@mailman.qth.net
Subject: Re
aft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred
Jensen
Sent: Wednesday, December 28, 2016 12:57 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna
The Summits On The Air crowd, at least one of whom "runs" up mountains, has
had very good luck with end-fe
thrown on the ground is
adequate.
I too have had excellent results with them.
73 Ron AC7AC
-Original Message-
From: Elecraft [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred
Jensen
Sent: Wednesday, December 28, 2016 12:57 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraf
A
[k...@sdellington.us]
Sent: Wednesday, December 28, 2016 1:32 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna
I've had good luck with the end fed 40 M half wave, too. I use it with
the KX1 to do CWT's on bicycle tours (in warmer weather). While the
transformer an
h.net] on behalf of K9MA
[k...@sdellington.us]
Sent: Wednesday, December 28, 2016 1:32 PM
To: elecraft@mailman.qth.net
Subject: Re: [Elecraft] Small QRP antenna
I've had good luck with the end fed 40 M half wave, too. I use it with
the KX1 to do CWT's on bicycle tours (in warmer weather).
I've had good luck with the end fed 40 M half wave, too. I use it with
the KX1 to do CWT's on bicycle tours (in warmer weather). While the
transformer and ATU apparently works, I wanted a really good match to
maximize output power, so I built a small QRP tuner for it:
The Summits On The Air crowd, at least one of whom "runs" up mountains,
has had very good luck with end-fed half-waves. The transformer weighs
next to nothing, and the rest is just wire. Requires no counterpoise,
very ground insensitive since it's fed at a voltage node. Also because
of that,
For about 50 years my usual portable antenna was a linked dipole, coax fed, and
usually rigged as an inverted V for 40, 30, and 20 meters. Performance was
usually very good especially if the apex was at least something like 25 feet.
However, this was heavy, took too much time to set up, and
ect: Re: [Elecraft] Small QRP antenna question
>Date: December 27, 2016 at 2:12:09 AM GMT-5
>To: Elecraft Reflector Reflector <elecraft@mailman.qth.net
><mailto:elecraft@mailman.qth.net>>
>For 80 meters, try a 53 foot wire in the air. For 40 meters and up, try a wire
&
For 80 meters, try a 53 foot wire in the air. For 40 meters and up, try a wire
26 to 29 feet long.
I use a 16 foot wire laying on the ground. That length either isn’t critical,
or changes electrical length due to capacitance to RF ground at every site. Or
both. Whatever, the ATU seems to deal
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