Today's Message Index:
----------------------
1. 02:56 AM - Tuning dipole aerial (fireflier)
2. 07:26 AM - Re: Tuning dipole aerial (Tim Andres)
3. 12:09 PM - Re: Tuning dipole aerial (John Cox)
4. 12:59 PM - Re: Tuning dipole aerial (Tim Andres)
5. 02:07 PM - Re: Tuning dipole aerial (John Cox)
Message 1
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| Subject: | Tuning dipole aerial |
Hi
I'm looking for some help with regards tuning in my dipole aerial as i seem to
have a slight problem.
I Have everything connected up to my swr meter and got the following readings at
the start
118.000 1.2
127.350 2.7
136.975 3.1
I have been trimming the copper tape of the dipole and the lower frequency swr
reading has increased and the mid frequency has decreased however there has been
no real effect on the hight frequency as this is still at a swr of 3.
I now have the copper tape legs cut to the lengths that were specified in my manual
480mm. I dont really want to cut much more off these as its not having any
effect on the top frequency swr value therefore i feel there is an underlying
issue that i need to sort out first?
With the 2 legs cut to 480mm i have the following swr readings
118.000 2.0
127.350 2.1
136.985 3.0
I would appreciated any help and advice that people have to offer to try and recrify
this problem for me. Im now not sure how to proceed to sort this problem
out.
I look forward to your replies.
Kind regards
Donald
--------
Fireflier
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=417402#417402
Message 2
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| Subject: | Re: Tuning dipole aerial |
Plot it with more data points to find its center freq.
If you think of it in terms of the "higher the frequency the shorter the element",
it was resonant at 118 MHz, and after cutting (how much?) it's moved higher.
Is you meter designed for VHF?
Also, nearby objects including you can affect it. Try to place it vertical and
away from other objects. Both elements should be equal length, and you should
measure from the crotch of the separated coax.
Tim
> On Jan 22, 2014, at 2:55 AM, "fireflier" <fireflier@btinternet.com> wrote:
>
>
> Hi
> I'm looking for some help with regards tuning in my dipole aerial as i seem to
have a slight problem.
>
> I Have everything connected up to my swr meter and got the following readings
at the start
>
> 118.000 1.2
> 127.350 2.7
> 136.975 3.1
>
> I have been trimming the copper tape of the dipole and the lower frequency swr
reading has increased and the mid frequency has decreased however there has
been no real effect on the hight frequency as this is still at a swr of 3.
>
> I now have the copper tape legs cut to the lengths that were specified in my
manual 480mm. I dont really want to cut much more off these as its not having
any effect on the top frequency swr value therefore i feel there is an underlying
issue that i need to sort out first?
>
> With the 2 legs cut to 480mm i have the following swr readings
>
> 118.000 2.0
> 127.350 2.1
> 136.985 3.0
>
> I would appreciated any help and advice that people have to offer to try and
recrify this problem for me. Im now not sure how to proceed to sort this problem
out.
>
> I look forward to your replies.
>
> Kind regards
> Donald
>
> --------
> Fireflier
>
>
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=417402#417402
>
>
>
>
>
>
>
>
>
>
Message 3
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| Subject: | Re: Tuning dipole aerial |
Donald, you did not mention if the antenna was installed on Carbon Fibre,
Fiberglass or Aluminum skin. Aren't the copper tapes used to establish an
effective groundplane? Is it a concealed antenna? is it homemade or
manufactured? Tesla's are having problems with quality FM reception due to
dipole, concealed. Some owners thought the side mirrors were the concealed
antenna, Turns out the location was selected for cosmetics not function
along the rear window deck and use a two frequency combiner. Are you
assuming the coax connections were both done on the shielding correctly?
John
On Wed, Jan 22, 2014 at 7:26 AM, Tim Andres <tim2542@sbcglobal.net> wrote:
>
> Plot it with more data points to find its center freq.
> If you think of it in terms of the "higher the frequency the shorter the
> element", it was resonant at 118 MHz, and after cutting (how much?) it's
> moved higher.
>
> Is you meter designed for VHF?
> Also, nearby objects including you can affect it. Try to place it vertical
> and away from other objects. Both elements should be equal length, and you
> should measure from the crotch of the separated coax.
>
> Tim
>
> > On Jan 22, 2014, at 2:55 AM, "fireflier" <fireflier@btinternet.com>
> wrote:
> >
> fireflier@btinternet.com>
> >
> > Hi
> > I'm looking for some help with regards tuning in my dipole aerial as i
> seem to have a slight problem.
> >
> > I Have everything connected up to my swr meter and got the following
> readings at the start
> >
> > 118.000 1.2
> > 127.350 2.7
> > 136.975 3.1
> >
> > I have been trimming the copper tape of the dipole and the lower
> frequency swr reading has increased and the mid frequency has decreased
> however there has been no real effect on the hight frequency as this is
> still at a swr of 3.
> >
> > I now have the copper tape legs cut to the lengths that were specified
> in my manual 480mm. I dont really want to cut much more off these as its
> not having any effect on the top frequency swr value therefore i feel there
> is an underlying issue that i need to sort out first?
> >
> > With the 2 legs cut to 480mm i have the following swr readings
> >
> > 118.000 2.0
> > 127.350 2.1
> > 136.985 3.0
> >
> > I would appreciated any help and advice that people have to offer to try
> and recrify this problem for me. Im now not sure how to proceed to sort
> this problem out.
> >
> > I look forward to your replies.
> >
> > Kind regards
> > Donald
> >
> > --------
> > Fireflier
> >
> >
> >
> >
> > Read this topic online here:
> >
> > http://forums.matronics.com/viewtopic.php?p=417402#417402
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
>
>
Message 4
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| Subject: | Re: Tuning dipole aerial |
Copper foil dipoles are pretty common in glass airplanes. Jim Weir use to se
ll a kit and book, I don't think he's shipping them anymore but I'm assuming
Donald's working from that recipe. He did mention it is a dipole.
Tim
> On Jan 22, 2014, at 12:08 PM, John Cox <rv10pro@gmail.com> wrote:
>
> Donald, you did not mention if the antenna was installed on Carbon Fibre,
Fiberglass or Aluminum skin. Aren't the copper tapes used to establish an e
ffective groundplane? Is it a concealed antenna? is it homemade or manufact
ured? Tesla's are having problems with quality FM reception due to dipole, c
oncealed. Some owners thought the side mirrors were the concealed antenna, T
urns out the location was selected for cosmetics not function along the rear
window deck and use a two frequency combiner. Are you assuming the coax co
nnections were both done on the shielding correctly?
>
> John
>
>
>> On Wed, Jan 22, 2014 at 7:26 AM, Tim Andres <tim2542@sbcglobal.net> wrote
:
>>
>> Plot it with more data points to find its center freq.
>> If you think of it in terms of the "higher the frequency the shorter the e
lement", it was resonant at 118 MHz, and after cutting (how much?) it's move
d higher.
>>
>> Is you meter designed for VHF?
>> Also, nearby objects including you can affect it. Try to place it vertica
l and away from other objects. Both elements should be equal length, and you
should measure from the crotch of the separated coax.
>>
>> Tim
>>
>> > On Jan 22, 2014, at 2:55 AM, "fireflier" <fireflier@btinternet.com> wro
te:
>> >
com>
>> >
>> > Hi
>> > I'm looking for some help with regards tuning in my dipole aerial as i s
eem to have a slight problem.
>> >
>> > I Have everything connected up to my swr meter and got the following re
adings at the start
>> >
>> > 118.000 1.2
>> > 127.350 2.7
>> > 136.975 3.1
>> >
>> > I have been trimming the copper tape of the dipole and the lower freque
ncy swr reading has increased and the mid frequency has decreased however th
ere has been no real effect on the hight frequency as this is still at a swr
of 3.
>> >
>> > I now have the copper tape legs cut to the lengths that were specified
in my manual 480mm. I dont really want to cut much more off these as its no
t having any effect on the top frequency swr value therefore i feel there is
an underlying issue that i need to sort out first?
>> >
>> > With the 2 legs cut to 480mm i have the following swr readings
>> >
>> > 118.000 2.0
>> > 127.350 2.1
>> > 136.985 3.0
>> >
>> > I would appreciated any help and advice that people have to offer to tr
y and recrify this problem for me. Im now not sure how to proceed to sort th
is problem out.
>> >
>> > I look forward to your replies.
>> >
>> > Kind regards
>> > Donald
>> >
>> > --------
>> > Fireflier
>> >
>> >
>> >
>> >
>> > Read this topic online here:
>> >
>> > http://forums.matronics.com/viewtopic.php?p=417402#417402
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>>
>> ==========
>> t" target="_blank">http://www.matronics.com/Navigator?Avionics-List
>> ==========
>> http://forums.matronics.com
>> ==========
>> le, List Admin.
>> ="_blank">http://www.matronics.com/contribution
>> ==========
>
>
>
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3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3
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=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>
Message 5
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| Subject: | Re: Tuning dipole aerial |
Dave hasn't answered up, but the math does not look right. Assuming a
concealed dipole, the starting measurement for a 1/4 wave in the mid band
of the frequencies desired might have been 564.1 mm or 22.2". Trimming it
to 488 moves that SWR towards the higher end frequency giving rise to the
loss of 118mHz for SWR = 1.2 and then heading south to the more undesirable
2.0. Just a perspective. Maybe he is going 1/8 wave, no ground plane and
properly matched BALUN for the coax to the transceiver??
John
On Wed, Jan 22, 2014 at 12:58 PM, Tim Andres <tim2542@sbcglobal.net> wrote:
> Copper foil dipoles are pretty common in glass airplanes. Jim Weir use to
> sell a kit and book, I don't think he's shipping them anymore but I'm
> assuming Donald's working from that recipe. He did mention it is a dipole.
> Tim
>
> On Jan 22, 2014, at 12:08 PM, John Cox <rv10pro@gmail.com> wrote:
>
> Donald, you did not mention if the antenna was installed on Carbon Fibre,
> Fiberglass or Aluminum skin. Aren't the copper tapes used to establish an
> effective groundplane? Is it a concealed antenna? is it homemade or
> manufactured? Tesla's are having problems with quality FM reception due to
> dipole, concealed. Some owners thought the side mirrors were the concealed
> antenna, Turns out the location was selected for cosmetics not function
> along the rear window deck and use a two frequency combiner. Are you
> assuming the coax connections were both done on the shielding correctly?
>
> John
>
>
> On Wed, Jan 22, 2014 at 7:26 AM, Tim Andres <tim2542@sbcglobal.net> wrote:
>
>>
>> Plot it with more data points to find its center freq.
>> If you think of it in terms of the "higher the frequency the shorter the
>> element", it was resonant at 118 MHz, and after cutting (how much?) it's
>> moved higher.
>>
>> Is you meter designed for VHF?
>> Also, nearby objects including you can affect it. Try to place it
>> vertical and away from other objects. Both elements should be equal length,
>> and you should measure from the crotch of the separated coax.
>>
>> Tim
>>
>> > On Jan 22, 2014, at 2:55 AM, "fireflier" <fireflier@btinternet.com>
>> wrote:
>> >
>> fireflier@btinternet.com>
>> >
>> > Hi
>> > I'm looking for some help with regards tuning in my dipole aerial as i
>> seem to have a slight problem.
>> >
>> > I Have everything connected up to my swr meter and got the following
>> readings at the start
>> >
>> > 118.000 1.2
>> > 127.350 2.7
>> > 136.975 3.1
>> >
>> > I have been trimming the copper tape of the dipole and the lower
>> frequency swr reading has increased and the mid frequency has decreased
>> however there has been no real effect on the hight frequency as this is
>> still at a swr of 3.
>> >
>> > I now have the copper tape legs cut to the lengths that were specified
>> in my manual 480mm. I dont really want to cut much more off these as its
>> not having any effect on the top frequency swr value therefore i feel there
>> is an underlying issue that i need to sort out first?
>> >
>> > With the 2 legs cut to 480mm i have the following swr readings
>> >
>> > 118.000 2.0
>> > 127.350 2.1
>> > 136.985 3.0
>> >
>> > I would appreciated any help and advice that people have to offer to
>> try and recrify this problem for me. Im now not sure how to proceed to sort
>> this problem out.
>> >
>> > I look forward to your replies.
>> >
>> > Kind regards
>> > Donald
>> >
>> > --------
>> > Fireflier
>> >
>> >
>> >
>> >
>> > Read this topic online here:
>> >
>> > http://forums.matronics.com/viewtopic.php?p=417402#417402
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>>
>> ==========
>> t" target="_blank">http://www.matronics.com/Navigator?Avionics-List
>> ==========
>> http://forums.matronics.com
>> ==========
>> le, List Admin.
>> ="_blank">http://www.matronics.com/contribution
>> ==========
>>
>>
>>
>>
> *
>
> D============================================
> ics-List"">http://www.matronics.com/Navigator?Avionics-List <http://www.matronics.com/Navigator?Avionics-List>
> D============================================
> //forums.matronics.com <http://forums.matronics.com>
> D============================================
> ot;">http://www.matronics.com/contribution <http://www.matronics.com/contribution>
> D============================================
>
> *
>
> *
>
>
> *
>
>
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