Foil antenna and carbon fiber

[BD5ER]

My Internet search didn't turn up what I was looking for so I came here for
advice. The task at hand is the installation of a foil antenna in a composite
canard which would ordinarily be a rather routine task for the plane - a
Quickie - but in this case there are some carbon fiber rods at 25% chord that
make placement impossible without having the foil either near some of the
carbon or metal components.

My question: How much does the carbon fiber rods affect the antenna
performance compared to a few bits of isolated metal (elevator hinge) and does
it make a significant difference if the carbon fiber is PAN or Pitch?

[Roger Halstead]

On 30 Jul 2003 17:00:38 GMT, (BD5ER) wrote:

>My Internet search didn't turn up what I was looking for so I came here for
>advice. The task at hand is the installation of a foil antenna in a composite
>canard which would ordinarily be a rather routine task for the plane - a
>Quickie - but in this case there are some carbon fiber rods at 25% chord that
>make placement impossible without having the foil either near some of the
>carbon or metal components.
>
>My question: How much does the carbon fiber rods affect the antenna
>performance compared to a few bits of isolated metal (elevator hinge) and does
>it make a significant difference if the carbon fiber is PAN or Pitch?

I don't know the specific answer for your situation, but the Glasair
III uses a carbon fiber horizontal stabilizer and they mount the
antenna right inside it. up against the carbon fiber lay-up.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

[Fastglasair]

>A_horizontail_comm antenna?

No, its should not be as I'm sure Roger knows and did not mean a comm antenna.
It is either a Marker beacon antenna (horiz stab is the best location due to
the MKR antenna length) or a VOR nav antenna.

[BD5ER]

>I don't know the specific answer for your situation, but the Glasair
>III uses a carbon fiber horizontal stabilizer and they mount the
>antenna right inside it. up against the carbon fiber lay-up.

Thanks, That answers my essential question and I can now position my nav
antenna. I'm familure with your G3 structure but didn't know that this was a
common place for an antenna. If it works in that application it should work in
mine.

[Jay]

You're not going to know until you put it in there and measure the
VSWR. But the good news is you can tune the antenna/feed-line after
its mounted but before you button things up. The question I'd have
about using a foil antenna attatched to a structure that flexes (like
a wing spar) is you may someday have a break in the foil after the
foil fatigues and then have a flakey antenna the behaves differently
in flight than on the ground when you're trying to debug it.


(BD5ER) wrote in message >...
> My Internet search didn't turn up what I was looking for so I came here for
> advice. The task at hand is the installation of a foil antenna in a composite
> canard which would ordinarily be a rather routine task for the plane - a
> Quickie - but in this case there are some carbon fiber rods at 25% chord that
> make placement impossible without having the foil either near some of the
> carbon or metal components.
>
> My question: How much does the carbon fiber rods affect the antenna
> performance compared to a few bits of isolated metal (elevator hinge) and does
> it make a significant difference if the carbon fiber is PAN or Pitch?

[Larry Smith]

"Jay" > wrote in message
m...
> You're not going to know until you put it in there and measure the
> VSWR. But the good news is you can tune the antenna/feed-line after
> its mounted but before you button things up. The question I'd have
> about using a foil antenna attatched to a structure that flexes (like
> a wing spar) is you may someday have a break in the foil after the
> foil fatigues and then have a flakey antenna the behaves differently
> in flight than on the ground when you're trying to debug it.

You insert the foil antenna inside a lightweight sheath which is affixed to
the inner skin of the horiz stab. Or the spar or whatever. The foil, like
that which you can purchase at RS, can flex inside the sheath and not break.
>
>

[Roger Halstead]

On 31 Jul 2003 09:54:33 -0700, (Jay) wrote:

>You're not going to know until you put it in there and measure the
>VSWR. But the good news is you can tune the antenna/feed-line after
>its mounted but before you button things up. The question I'd have
>about using a foil antenna attatched to a structure that flexes (like
>a wing spar) is you may someday have a break in the foil after the
>foil fatigues and then have a flakey antenna the behaves differently
>in flight than on the ground when you're trying to debug it.

The wing and horizontal stab in the G-III do not flex any where near
what you will find in a standard aluminum wing and horizontal stab in
something like a Bonanza. The spar in the wing is *massive* and that
horizontal stab is rigid. You can stand on one side and not see it
flex. I'd not want to do that on my Deb.

Roger
>
>
(BD5ER) wrote in message >...
>> My Internet search didn't turn up what I was looking for so I came here for
>> advice. The task at hand is the installation of a foil antenna in a composite
>> canard which would ordinarily be a rather routine task for the plane - a
>> Quickie - but in this case there are some carbon fiber rods at 25% chord that
>> make placement impossible without having the foil either near some of the
>> carbon or metal components.
>>
>> My question: How much does the carbon fiber rods affect the antenna
>> performance compared to a few bits of isolated metal (elevator hinge) and does
>> it make a significant difference if the carbon fiber is PAN or Pitch?

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

[Jim Weir]

You can make an antenna out of limp spaghetti and mount it inside a copper
septic tank if you wish -- and everything gets better from there. I cannot
believe that an antenna inside of or laid directly on carbon fiber will work.
If somebody actually has one WORKING, please post your test results or flight
test results.

Jim



Roger Halstead >
shared these priceless pearls of wisdom:

->I don't know the specific answer for your situation, but the Glasair
->III uses a carbon fiber horizontal stabilizer and they mount the
->antenna right inside it. up against the carbon fiber lay-up.


Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

[Jim Weir]

Well, since I've been accused of baiting an argument in these ngs, perhaps now I
am considered a master baiter.

Ahem.

Instead of answering you directly, I will instead give you general advice. I
can't honestly tell enuf about the problem from the description given to point
you straight. (BTW, when you post a question during Oshkosh week, be prepared
to wait for answers.)

The CENTER of the antenna (where the coax connects) is totally numb to
metal/carbon. The TIPS of the antenna are the most sensitive. The bigger the
metal/carbon the more effect it has. I could make filthy analogies, but I'll
let them rest.

Keep the TIPS as far away from large expanses of metal/carbon as you can.
That's the best advice I can give.

Jim



(BD5ER)
shared these priceless pearls of wisdom:


->Nav antenna in the lower surface of a canard (tandem wing, big canard). I
have
->a choice of the tip of one foil strip centered (about 6 inch to either)
between
->an isolated bolt and fitting in the outer elevator hinge and the carbon fiber
->spar, or crossing the spar about 8 inches from the tip.
Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com

[BD5ER]

>(BTW, when you post a question during Oshkosh week, be prepared
>to wait for answers.)

FULLY understood. I consider any answer from you here a considerable public
service on your part. How many other professionals take the time coddle the
masses in such a personal and direct way?....... and for free!

Thanks

[Roger Halstead]

On Tue, 05 Aug 2003 08:30:49 -0700, Jim Weir > wrote:

>You can make an antenna out of limp spaghetti and mount it inside a copper
>septic tank if you wish -- and everything gets better from there. I cannot
>believe that an antenna inside of or laid directly on carbon fiber will work.
>If somebody actually has one WORKING, please post your test results or flight
>test results.

I tend to agree with you Jim...I'm just relaying where the
manufacturer of the plane said to mount the antenna. course they
didn't give any guarantees as to how well it'd work.

It took you comments to jar my memory and realize that ain't where I'm
gonna mount it.

I sure wouldn't mount my ham antennas there as I'd probably set the
thing on fire. OTOH, I always figure when I key the mike in the car,
if the tires don't skid I'm not running enough power. <:-))

Then again, it's been almost a year since I even turned on the
filaments of the amp in the HF station at home.

Roger Halstead (K8RI EN73 & ARRL Life Member)
www.rogerhalstead.com
N833R World's oldest Debonair? (S# CD-2)

>
>Jim
>
>
>
>Roger Halstead >
>shared these priceless pearls of wisdom:
>
>->I don't know the specific answer for your situation, but the Glasair
>->III uses a carbon fiber horizontal stabilizer and they mount the
>->antenna right inside it. up against the carbon fiber lay-up.
>
>
>Jim Weir (A&P/IA, CFI, & other good alphabet soup)
>VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
>http://www.rst-engr.com

[Jim Weir]

{;-)

You people are outRAGEOUS in your humor, even if you can't spell a person who
argues as a debater.

God bless, I love you all...

{;-)

Jim



->Get him arguing about base station antennas and he could be referred to
->as a mast debator.

Jim Weir (A&P/IA, CFI, & other good alphabet soup)
VP Eng RST Pres. Cyberchapter EAA Tech. Counselor
http://www.rst-engr.com