Hello Tim,
I did something like that. See part of sheet below. As you said, tuners love
it if you take this into consideration. 73, Bruce, W8HW
Antenna Length in Ft. by Bruce Campbell
Mhz 0.125 0.25 0.375 0.5 0.625 0.75
145 0.81 1.61 2.42 3.23 4.03 4.84
50.1 2.34 4.67 7.01 9.34 11.68 14.01
28.3 4.13 8.27 12.40 16.54 20.67 24.81
24.93 4.69 9.39 14.08 18.77 23.47 28.16
21.1 5.55 11.09 16.64 22.18 27.73 33.27
18.1 6.46 12.93 19.39 25.86 32.32 38.78
14.1 8.30 16.60 24.89 33.19 41.49 49.79
10.107 11.58 23.15 34.73 46.30 57.88 69.46
7.04 16.62 33.24 49.86 66.48 83.10 99.72
6.98 16.76 33.52 50.29 67.05 83.81 100.57
5.3715 21.78 43.56 65.34 87.13 108.91 130.69
3.52 33.24 66.48 99.72 132.95 166.19 199.43
3.57 32.77 65.55 98.32 131.09 163.87 196.64
1.825 64.11 128.22 192.33 256.44 320.55 384.66
1.9 61.58 123.16 184.74 246.32 307.89 369.47
--------------------
----- Original Message -----
From: "Tim Ellison" <telli...@itsco.com>
To: "Fred Howell" <fhowell...@att.net>; "'Fred Brandeberry'"
<fbrande...@comcast.net>; "'flex list'" <FlexRadio@flex-radio.biz>
Sent: Tuesday, December 21, 2010 6:57 PM
Subject: Re: [Flexradio] Questions about antennas and spectral displays...
OK. I believe ya <wink>
The link to the spreadsheet is:
http://support.flex-radio.com/Downloads.aspx?id=357
A little background.
This spreadsheet started out as a "brain stimulator exercise" during a
mind numbing extended 6 month stay in Jakarta Indonesia in 2004. (don't
ask). Back then, I was using an AH-4 antenna coupler and it, like the
SGCs do not like wire lengths that are even half wave multiples of the
transmitting frequency. Since the AH-4 can match 160-6m, if you calculate
the wire length of all the 1/2 wavelength points, you get a bunch of
numbers. Furthermore, the wire length is different for loops and dipoles
at the same frequency. A bunch more numbers.
When I was going to get home from Indonesia, I was going to put up a new
antenna for the AH-4, so this is how the spreadsheet came about. This
spreadsheet calculates the 1/2 wavelength (fundamental and harmonics) or
high current point of various wire antennas for all of the ham bands.
These values in feet (or meters depending on the units that the constant
is in) are the ones you are NOT supposed to use with antenna couplers,
like the AH-4, SGC and the CG-3000. I graph these high current points in a
separate spreadsheet. What you are looking for are the "holes" or gaps in
the graph and that is where you are supposed to cut the wire length to.
It is slightly counter intuitive, but it works visually.
After the initial version, I made changes to it while on business trips
out of the country, so each version has the name of the city I was in when
making the change.
There is a help file of sorts that you can access that explains it
somewhat better. It is embedded in the spreadsheet.
It is an Excel 2003 spreadsheet and some of the fields are locked to
prevent it from getting hosed up and to protect my intellectual property
:-)
Finally, the basic disclosure. I don't claim this works and have no
liability from its use. It is "as is", but I use it all the time and it
hasn't failed me. Sending me an e-mail asking me how it works or to use
it, may or may not illicit a response.
I was working on a more complex version that calculated the wire length
based on frequency, antenna type and diameter of the radiator, but I never
finished it. It was also going to find "sweet spot" wire lengths to use
rather than looking for the "holes" in the graph to determine the sweet
spot. Maybe one day...
Have fun. Ho Ho Ho.
-Tim
-----Original Message-----
From: Fred Howell [mailto:fhowell...@att.net]
Sent: Tuesday, December 21, 2010 5:42 PM
To: Tim Ellison; 'Fred Brandeberry'; 'flex list'
Subject: RE: [Flexradio] Questions about antennas and spectral displays...
Oh, Please Santa, Please. I promise that I have been a good boy... just
don't ask my wife.
Fred W2VQS
-----Original Message-----
From: flexradio-boun...@flex-radio.biz
[mailto:flexradio-boun...@flex-radio.biz] On Behalf Of Tim Ellison
Sent: Tuesday, December 21, 2010 4:36 PM
To: Fred Brandeberry; flex list
Subject: Re: [Flexradio] Questions about antennas and spectral displays...
If everyone is a good little boy and girl, the Ham Santa just might be
able to dig up that spreadsheet and post it somewhere as an early stocking
stuffer :-)
-Tim
-----Original Message-----
From: Fred Brandeberry [mailto:fbrande...@comcast.net]
Sent: Tuesday, December 21, 2010 5:24 PM
To: Tim Ellison
Subject: Re: [Flexradio] Questions about antennas and spectral displays...
I wonder if you might be willing to share that spreadsheet?
73,
Fred
WA8KCW
-----Original Message-----
From: Tim Ellison
Sent: Tuesday, December 21, 2010 1:29 PM
To: David McClain ; flex list
Subject: Re: [Flexradio] Questions about antennas and spectral displays...
A 43 foot vertical or end-fed or a 86' dipole.
I created a spreadsheet several years back that found all of the non-even
harmonic radiator lengths from 160-6m and then graphed the points so you
could visually "find" gaps in the graph to pick your antenna length. It
even had an option for dipoles and loops.
-Tim
-----Original Message-----
From: flexradio-boun...@flex-radio.biz
[mailto:flexradio-boun...@flex-radio.biz] On Behalf Of David McClain
Sent: Tuesday, December 21, 2010 1:50 PM
To: flex list
Subject: [Flexradio] Questions about antennas and spectral displays...
I think I know the answer, but I want to double check... That 43 foot
antenna... is it an end-fed random wire off the back of the tuner? or a
center-fed dipole, with total span 43 feet?
Also, as a side question... Anyone happen to know why all the other
higher-end modern rigs (Icom, Kenwood, Yaesu, Ten-Tec), use swept spectrum
analyzers instead of using an FFT like Flex Radio uses?
- de Dave, N7AIG
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