 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
bakerocb
Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA
|
 Posted: Mon Oct 23, 2006 10:44 am Post subject: antenna interference |
 |
|
10/23/2006
Hello Bob Nuckolls and other antenna experts,
Some time ago a fellow builder installed an Advanced Aircraft Electronics
comm antenna in
the vertical stab of his composite (fiberglass) airplane. The antenna is a
straight one piece dipole with balun in center.
The reception was tested with a radio and found to be excellent. In
attaching the rudder, a full length aluminum piano style hinge was
installed. This is one of the builder's modifications to the original plans
that called for separate short segments of aluminum piano type hinge for the
rudder.
When testing the reception again with the same transmitter the reception was
practically nonexistent.
The builder would like to retain use of the antenna and come up with a
(nearly continuous) hinge solution that will permit adequate transmission
and reception. Various solutions have been proposed:
1) Use a continuous piano type hinge made out of plastic. (Guden makes
them).
2) Use a continuous piano type hinge made out of carbon fiber.
http://www.carbinge.com/index.html
3) Use a basically continuous full length piano type hinge made out of
carbon fiber, but cut it a number of times during its length into shorter
than full length segments.
4) Use a basically continuous full length piano type hinge made out of
aluminum, but cut it a number of times during its length into shorter than
full length segments.
5) Abandon the continuous hinge concept and install separate short segments
of metal hinge as the plans call for.
We would appreciate your inputs and advice. Thanks.
OC
| | - The Matronics Avionics-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Avionics-List |
|
|
|
| Back to top |
|
 |
douglist(at)macnauchtan.c
Guest
|
| Posted: Mon Oct 23, 2006 12:49 pm Post subject: antenna interference |
|
|
At 14:41 -0400 10/23/06, <bakerocb(at)cox.net> wrote:
| Quote: | 4) Use a basically continuous full length piano type hinge made out of aluminum, but cut it a number of times during its length into shorter than full length segments.
|
It might be sufficient to cut it once only a few inches away from the center.
It might also be enough to cut just the rod into two pieces with an insulator between them
You might also try bonding both sides of the hinge to airframe ground. Well. . . that doesn't mean connecting it to the fiberglass. The idea is to move the resonance to longer wavelengths by making the hinge electrically longer as opposed to cutting it to make it shorter.
And the # 10 thought. . . . Remove the dipole antenna and put a BNC connector on the hinge.
--
--> If it's not on fire it's a software problem. <--
| | - The Matronics Avionics-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Avionics-List |
|
|
|
| Back to top |
|
|
Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
|
| Posted: Mon Oct 23, 2006 4:08 pm Post subject: antenna interference |
|
|
Plastic or carbon fibre.
Any short pieces of metal can be parasitic elements. Pieces shorter than
4" spaced at least 4" apart shouldn't cause the parasitic signal loss you
experience. Try holding the short hinge segments to your vertical stab.
with string before you commit to an installation.
One Question... Is the leading edge of your rudder reinforced with metal ??
If so the hinge is only part of your problem. The system you have installed
should be one of the best available. Completely omni directional.
Noel
[quote] --
| | - The Matronics Avionics-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Avionics-List |
|
_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats |
|
| Back to top |
|
|
Float Flyr
Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland
|
| Posted: Mon Oct 23, 2006 4:18 pm Post subject: antenna interference |
|
|
I don't know what kind of plane this antenna is in but it sounds like part
of the problem is the hinge is very close to 1/2 lambda (18-20") away from
the antenna and is oriented parallel to it. Changing the resonant length of
the hinges is a good starting place. Grounding the hinge will probably
result in an RF shadow somewhere behind the plane. I think the best thing
to do is to look at shorter segments of varying lengths with varying spaces
between the segments. Or go straight to plastic or composite hinges...
Don't forget the hinge pins also should be non metallic if plastic or
composite hinges are used.
Noel
[quote] --
| | - The Matronics Avionics-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Avionics-List |
|
_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats |
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
