Today's Message Index:
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1. 09:47 AM - Bob Archer comm antenna dimensions ? (GTH)
2. 10:47 AM - Re: Bob Archer comm antenna dimensions ? (Charlie England)
3. 11:38 AM - Re: Bob Archer comm antenna dimensions ? (GTH)
4. 01:16 PM - Re: Bob Archer comm antenna dimensions ? (Charlie England)
5. 08:48 PM - Re: Bob Archer comm antenna dimensions ? (The Kuffels)
6. 09:27 PM - Re: Bob Archer comm antenna dimensions ? (The Kuffels)
Message 1
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Subject: | Bob Archer comm antenna dimensions ? |
Hi all,
Some 15 years ago we ordered a Bob Archer comm antenna for installation
in our wingtip, and have been very satisfied with it.
Here is a sketch of our 15 year old antenna :
A buddy of mine launches into another project and just received a new
Archer antenna to install in his tail fin, but the dimensions and shape
seem different, and the rivets prevent the upper segment from being
swept up to fit into the tail.
Although the antenna is labelled "Comm", we are finally not sure the
model is a VHF one.
Does any of you gentlemen have any information as to the shape and
dimensions of the present time Archer comm antennas - or VOR antennas -
so we could clarify the matter ?
Thanks in advance,
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
Message 2
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Subject: | Re: Bob Archer comm antenna dimensions ? |
On 12/8/2018 11:46 AM, GTH wrote:
>
> Hi all,
>
> Some 15 years ago we ordered a Bob Archer comm antenna for
> installation in our wingtip, and have been very satisfied with it.
>
> Here is a sketch of our 15 year old antenna :
>
>
> A buddy of mine launches into another project and just received a new
> Archer antenna to install in his tail fin, but the dimensions and
> shape seem different, and the rivets prevent the upper segment from
> being swept up to fit into the tail.
>
> Although the antenna is labelled "Comm", we are finally not sure the
> model is a VHF one.
>
> Does any of you gentlemen have any information as to the shape and
> dimensions of the present time Archer comm antennas - or VOR antennas
> - so we could clarify the matter ?
>
>
> Thanks in advance,
>
>
> --
> Best regards,
> Gilles
> http://contrails.free.fr
> http://lapierre.skunkworks.free.fr
Pretty sure that if you could see side by side images of all the
Sportcraft antennas, you'd see significant differences among the various
antennas. IIRC, there are different models for RV-4-8, the -9, & -10
wing tips. The vertical fin would be yet another design. The VOR
antennas would be yet another set.
Did he make sure that the model he bought is recommended for his a/c,
and for the location where he intends to mount it?
Charlie
---
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Message 3
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Subject: | Re: Bob Archer comm antenna dimensions ? |
/Le 08/12/2018 19:49, Charlie England a crit:
/
> /Pretty sure that if you could see side by side images of all the
> Sportcraft antennas, you'd see significant differences among the
> various antennas. IIRC, there are different models for RV-4-8, the
> -9, & -10 wing tips. The vertical fin would be yet another design. The
> VOR antennas would be yet another set.
> / /
> Did he make sure that the model he bought is recommended for his a/c,
> and for the location where he intends to mount it?
> /
Hi Charlie,
Thank you for responding.
His project is a composite homebuilt that certainly no one knows outside
our country.
The antenna is to be located in the glass fiber fin, but as it is a
small airplane, there no room for
a 1/2 wave antenna.
Provided the model is a correct comm antenna the actual question is, can
we pivot the radiating element so as to match the fin, like in red in
the following diagram
Of course this would involve removing some rivets, but from an
electrical point of view, would such a "sweep" be acceptable ?
Thank you,
--
Best regards,
Gilles
http://contrails.free.fr
http://lapierre.skunkworks.free.fr
Message 4
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Subject: | Re: Bob Archer comm antenna dimensions ? |
On Sat, Dec 8, 2018 at 1:42 PM GTH <gilles.thesee@free.fr> wrote:
>
> *Le 08/12/2018 =C3- 19:49, Charlie England a =C3=A9crit : *
>
>
> *Pretty sure that if you could see side by side images of all the
> Sportcraft antennas, you'd see significant differences among the various
> antennas. IIRC, there are different models for RV-4-8, the -9, & -10 win
g
> tips. The vertical fin would be yet another design. The VOR antennas woul
d
> be yet another set. *
>
> * Did he make sure that the model he bought is recommended for his a/c,
> and for the location where he intends to mount it? *
>
>
> Hi Charlie,
>
> Thank you for responding.
> His project is a composite homebuilt that certainly no one knows outside
> our country.
> The antenna is to be located in the glass fiber fin, but as it is a small
> airplane, there no room for
> a 1/2 wave antenna.
> Provided the model is a correct comm antenna the actual question is, can
> we pivot the radiating element so as to match the fin, like in red in the
> following diagram
>
>
> Of course this would involve removing some rivets, but from an electrical
> point of view, would such a "sweep" be acceptable ?
>
> Thank you,
>
> --
> Best regards,
> Gilles
> http://contrails.free.fr
> http://lapierre.skunkworks.free.fr
>
I'm no antenna expert, but I'd bet that a base loaded whip (like a 'rubber
ducky' off a handheld) would work about as well as radically altering the
tuning of the Archer antenna. Or maybe not. :-)
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Message 5
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Subject: | Re: Bob Archer comm antenna dimensions ? |
Gilles,
I used to be an antenna expert.
The Archer antenna should work better with the radiating element unbent. I
n fact, it would work best with the radiating element at 90 degrees to the
base. But you might have a bigger issue. This antenna requires a mass of
metal, like a wing, electrically connected along the base to serve as a gro
und plane. Does the aircraft have a metal fuselage or stabilizer.
Another issue is the rudder tube, if metal. If the distance from the front
of the rudder to the antenna radiator is too short, say around a foot or t
wo, you will have a null in your reception toward the rear. The problem is
even worse if the rudder is also metal.
A possible solution might be a bent 1/2 wave dipole. The 1/4 wave part fed
by the coax center wire would fit up the fin from the base, essentially th
e same as the radiating element on the Archer. The other half of the dipol
e would be attached forward to the underside of the fuselage top. The shie
ld of the coax would be attached to this other half. Sort of an L in profi
le from the right side with the coax cable attached at the bend. I would u
se copper sheet 1/2 - 3/4 inch wide for the elements.
If this simple antenna is not possible for some reason then more complex ar
rangements start appearing such as dual end coil loaded dipoles. This coul
d be made to fit in the fin but then you are getting into the area of much
tinkering and antenna analyzers, etc.
Tom Kuffel
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Message 6
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Subject: | Re: Bob Archer comm antenna dimensions ? |
Gilles,
What model Archer antenna does your friend have. Archer offers a compresse
d dipole (looks like a weird "3") model SA006 which is 26.5" tall by 12" wi
de.
At some $190 it is a bit pricey but should fit if your unbent wing tip mode
l would have.
Tom
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