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-   -   Antennas (http://www.rcuniverse.com/forum/questions-answers-154/11251990-antennas.html)

gphil 10-05-2012 10:32 AM

Antennas
 
The plane is coming along grear thanks to you guys and helping. Now, where do most guys run the antenna wire? My two have it on the outside. Tubes on the inside???? Stick 60 and was thinking of inside the plane. Always thanks and will be watching. gphil

BarracudaHockey 10-05-2012 10:50 AM

RE: Antennas
 
72mhz antennas can be run inside a wood fuselsage w/o loss in range.

jetmech05 10-05-2012 04:48 PM

RE: Antennas
 
You'll love it on the inside...no unsightly wire...no wire to get tangled in, nor break

KW_Counter 10-06-2012 05:44 AM

RE: Antennas
 
When wiring on the inside make sure the wire runs the length of the fuselage.
It does not need to be pulled taught, but don't coil it up.
The longer and straighter the better.

Good Luck,
KW_Counter

Gray Beard 10-06-2012 08:33 AM

RE: Antennas
 
I try to run as much of the wire inside the fuse as I can but often have a few inches sticking out the back. On others I run the wire through nyrod and out just behind the cockpit then to the V-stab. I just drill two small holes in the stab and lace the wire through them to hold it. I have one plane with it going out the bottom along the fuse. I glued small pieces of nyrod to the bottom of the fuse to hold it. As long as it's out of the way so I'm not stepping on it I'm OK with it.

speedracerntrixie 10-06-2012 10:16 AM

RE: Antennas
 
I would suggest keeping it away from metal pushrods or steel pull pull rudder cables. A couple inches is fine.

gphil 10-06-2012 10:34 AM

RE: Antennas
 
I saw one at the field today and his was on the bottom but my landings would take care of that one.   Current plane has it on the top going to vert stab and I am constantly hitting it or something making it loose so think going to try inside.   gphil

jaka 10-06-2012 11:38 AM

RE: Antennas
 
Hi!
On the inside!

LesUyeda 10-07-2012 06:14 AM

RE: Antennas
 
If you wrap the whole length around a soda straw, then stretch just enough to leave a few inches outside the tail, it will work fine inside the fuselage.

Les

KW_Counter 10-07-2012 07:28 AM

RE: Antennas
 
Quote:

If you wrap the whole length around a soda straw, then stretch just enough to leave a few inches outside the tail, it will work fine inside the fuselage.
Very BAD idea. By coiling it up you are de-tuning the antenna and reducing its sensitivity.
It needs to be as straight as possible. Its length is a precise fraction of the wavelength (frequency)
of the signal it is trying to receive.

Many people have done this and said it works fine.
However, if something does go wrong you will never know the reason.

Good Luck,
KW_Counter

speedracerntrixie 10-07-2012 07:58 AM

RE: Antennas
 

Quote:

ORIGINAL: KW_Counter

Quote:

If you wrap the whole length around a soda straw, then stretch just enough to leave a few inches outside the tail, it will work fine inside the fuselage.
Very BAD idea. By coiling it up you are de-tuning the antenna and reducing its sensitivity.
It needs to be as straight as possible. Its length is a precise fraction of the wavelength (frequency)
of the signal it is trying to receive.

Many people have done this and said it works fine.
However, if something does go wrong you will never know the reason.

Good Luck,
KW_Counter
Very true. Back in the late 70's when we flew AM, I would get a new RX and replace the antenna right away with a slightly longer peice of the same gauge. Then I would start doing range checks with a collapsed TX antenna. I would trim 1/4"off the RX antenna until at a time until I noticed no increase in range. Kind of a tune for the enviroment sort of thing.


AA5BY 10-07-2012 08:38 AM

RE: Antennas
 

Quote:

ORIGINAL: speedracerntrixie


Quote:

ORIGINAL: KW_Counter

Quote:

If you wrap the whole length around a soda straw, then stretch just enough to leave a few inches outside the tail, it will work fine inside the fuselage.
Very BAD idea. By coiling it up you are de-tuning the antenna and reducing its sensitivity.
It needs to be as straight as possible. Its length is a precise fraction of the wavelength (frequency)
of the signal it is trying to receive.

Many people have done this and said it works fine.
However, if something does go wrong you will never know the reason.

Good Luck,
KW_Counter
Very true. Back in the late 70's when we flew AM, I would get a new RX and replace the antenna right away with a slightly longer peice of the same gauge. Then I would start doing range checks with a collapsed TX antenna. I would trim 1/4'' off the RX antenna until at a time until I noticed no increase in range. Kind of a tune for the enviroment sort of thing.


Correct.... I've made rubber ducky antennas by spiraling the wire around a flexible core but the length of wire needed does change from that of a straight antenna.

LesUyeda 10-08-2012 06:11 AM

RE: Antennas
 
Oh Well. Since that is the technique I have been using since the mid '50s without mishap, I think I will just continue doing so.

We ARE each entitled to our own opinions, regardless of their accuracy, or basis in fact.

Les

speedracerntrixie 10-08-2012 07:19 AM

RE: Antennas
 

Quote:

ORIGINAL: LesUyeda

Oh Well. Since that is the technique I have been using since the mid '50s without mishap, I think I will just continue doing so.

We ARE each entitled to our own opinions, regardless of their accuracy, or basis in fact.

Les

Pretty much a dead issue now that we have 2.4 but by coiling the antenna you are simply reducing your range. Most models never reach the range limit as long as everything else is working correctly. Now back when I was flying 72 MHZ I was doing so on both competition sailplanes and 40% aerobatic airplanes that could easily get 1/2 mile away so the reduced range could in fact be an issue. IMO continuing to do something that is known to reduce the reliability of your aircraft is just stubborn. You are correct however and you are entitled to do as you please.


AA5BY 10-08-2012 10:58 AM

RE: Antennas
 
A short primer on antennas would conclude that they are most efficient when a standing wavelength of the frequency or division/multiplication thereof matches the electrical length of the antenna.

If an antenna lives in free space without proximity to other conductive materials then the electrical length is basically the same as the physical length. If however, there are conductive materials within proximity, then the electrical length is influenced and no longer matches the physical length.

A spiral antenna resembling a ducky antenna to shorten its physical length is influence by proximity to itself and the electrical length no longer matches the physical length of the wire.

I applaud the patience of the described method of making an antenna purposely long and then trimming it slightly shorter until the range is maximum. The technique shows creativity in the face of lack of equipment such as a grid dip meter or SWR bridge to assist in tuning the electrical length to be resonate with the frequency wavelength.

Fortunately, a degree of margin exist for RC control and some degradation doesn't usually cause problems.

acdii 10-08-2012 11:37 AM

RE: Antennas
 
Take a long thin tube and glue it inside the fuse away from the metal, and run your wire inside of it. If the wire is longer than the fuse, then let it come out the back where it wont get in the way or be damaged.

gphil 10-08-2012 03:35 PM

RE: Antennas
 
Thank fellas for all the good info.  Going to put it in a dubro ant tube and install in the fuz.    Lot of good input here from radio guys I can tell.  gphil

LesUyeda 10-09-2012 06:15 AM

RE: Antennas
 
"IMO continuing to do something that is known to reduce the reliability of your aircraft is just stubborn."

As far as YOU are concerned it reduces the reliability. As far as I am concerned I know better.

Les
WA6EER

Charlie P. 10-09-2012 05:42 PM

RE: Antennas
 

Quote:

ORIGINAL: LesUyeda

Oh Well. Since that is the technique I have been using since the mid '50s without mishap, I think I will just continue doing so.

We ARE each entitled to our own opinions, regardless of their accuracy, or basis in fact.

Les
I've done that without problems but the KEYis not to allow the wire to overlap. Wrap and tapeso it doesn't occur accidentally. No doubt it still shortens the range some.

But Iam a happy convertto 2.4GHz andnot worrying about it; though Imakesure mine stay at 90° with frame tubes or attached to a balsa right-angle.


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