Where to run antenna wire?
 

Does it matter if the antenna wire runs inside or outside the length of the plane? My instructions say to cut a hole in the side of the plane and run the antenna up to the top of the vertical stab. I'd rather run a tube down to the tail of the plane and have the antenna exit the aircraft there. Does it make a difference? I'm guessing no, but wanted to double check.

Thanks guys!

RE: Where to run antenna wire?
 

It doesn't make much difference. Some run it to the vertical and Dubro make a pretty slick mounting kit if you want to do that, or just make you own system. Some run it inside the fuselage and dangle it out the tail. I've seen some run it though the wing and have it coming out the wing tip but there's only a few aircraft where this is practical. It up to you, you just don't want to pinch the wire or get it in a position where it could be cut.

RE: Where to run antenna wire?
 

It doesn't matter much, inside or out, as long as it is straight. One guy a the field builds the antenna in the wing and uses a servo connection pin and socket to make the connection. I use a piece of plastic tubing as small as I can find and build it into the fuselage with an exit rear the rudder. Depending on the size of the plane, I either have nothing showing out side the plane, or just an inch or two. I just finished a Pheonix Fun Star and I used a tube and put the antenna in it, taping it to the end of the tube. I pushed the tube int the fuselage as far back as I coud and used some thick CA to spot glue it to a a former. There was about three inches to much wire so I puulled it forward into a long loop and taped it to the bottom of the fuse. Works fine.

I don't like it hanging outside the fuse, especially up to the top of the vertical stab. I loop a cord over the tail holding the plane on the bench and It pulls on the antenna if it is run externally.

Don

RE: Where to run antenna wire?
 

Great. Thanks.

RE: Where to run antenna wire?
 

A couple of things to be aware of-

If the plane is covered with a metallic covering that may be conductive it can shield the signal. Make sure you do a good range check if this is the case.

If you use a tube to contain the antenna wire, do not use a metal tube or anything that is conductive ie carbon fiber etc. Again, do a good range check whatever you do.

RE: Where to run antenna wire?
 

Also if you have a composite glass fuselage with carbon fibre in the layup DO NOT RUN THE AERIAL INSIDE THE FUZ.

RE: Where to run antenna wire?
 

Its a balsa skeleton with something like monokote covering. No carbon fiber, no metal (other than pieces of the push rods, etc.)

RE: Where to run antenna wire?
 

The antenna tube in the fuselage is about the cleanest. It will leave just a little excess hanging out. Many of the nicer ARF's and kits are designed with this option. Another clean way is to run is out the bottom of the fuselage just behind the wing. Glue a piece of fuel tubing through a hole there and pass the antenna through it. The tubing will keep the wood from cutting the antenna or the antenna from cutting into the wood. Then make a hook from a discarded servo arm and use a rubber band to connect the end f the antenna to your tail wheel bracket or eyelet screwed into the rear of the fuselage. The rubber band will hold the antenna wire straight and tight without over-stressing it. I also like to use a piece of servo arm to make a strain relief at the point where the wire exits the fuse. This prevents the wire from being pulled out of the receiver.

You can kind of see what I'm talking about on my old Cub. You can also see the tube I put in the right wing half on my scratch built profile Hots. It was easy to do on the scratch build since I could plan for it during wing construction. It really wouldn't work on a removable wing unfortunately. I'll toss in another shot of my old Tower trainer with the antenna going to the tip of the vertical stab.

RE: Where to run antenna wire?
 

You should have no problems with a tube inside the fuse as long as the push rod is not a metal rod that runs the length of the fuse.

RE: Where to run antenna wire?
 

So I can take the excess hanging out and loop it back inside the tube? This won't shorten my range (doubling up the antenna)?

RE: Where to run antenna wire?
 

DO NOT double the antenna back on itself. This in effect shortens the antenna. The folded back section will in effect cancel the signal received by the section where it is doubled. Let the excess hang out the back of the fuse. Do not fold or coil the excess at the RX for the same reason. The antenna should be straight from the Rx to the end, minor deviations are permissable such as routing the wire around the compartment, etc. Avoid running the wire near the servos or any large metal objects.

RE: Where to run antenna wire?
 

Great, thanks a lot! Didn't loop the antenna back int.

RE: Where to run antenna wire?
 

G'day Mate,
It only makes a difference if you have servos in the tail of the plane, servos make a lot of RF noise, & this noise will effect the RX, because of the close proximity of the end of the antenna, to the servos.
If no servos in the tail, it don't matter.

RE: Where to run antenna wire?
 

Take and clip a servo arm with two holes left in it. Thread your antenna wire through it, keep this inside your fuselage where your antenna comes out. If you tip your plane on the antenna this well stop the wire from pulling out of your RX.

RE: Where to run antenna wire?
 

Running the antenna outside the fuse was originally conceived back in the EARLY days of RC. With today's radios, it's really not necessary.

What I do is I take a piece of inner pushrod tubing about 8 - 10 inches shorter than the antenna and run the antenna wire through it and out the other end. Then tie a knot in the end so it won't go back in.

Now you can just run the tube inside the fuse and any excess can just loop itself around the radio compartment.

I have used this method for over 20 years with metal, wood and nylon pushrods and never had a problem.

One of the nicest things about it is: When you switch receivers from one plane to another, you can just slide the tube out of one plane and into the next.

RE: Where to run antenna wire?
 

Just do not cut the antenna "to length". It must remain the same length it was when you got it new.

The antenna is cut to a specific length so that it matches the wavelength of the frequency you are using.

For instance, 72MHz requires a full wave length antenna to be 13.7 feet long. Our antennas are usually cut to 1/4 wavelength, or 3.4 feet.

So, if you measure your antenna from the point where it joins the circuit board within the receiver to the tip, you will come up with something on the order of 3.4 feet or about 41 inches. This will vary slightly because of the way the manufacturer may "load" the front end of the receiver, but generally, that's the electrical length that the antenna must be to operate properly at the 72 MHz frequency.

Soooo.. don't cut it shorter to fit the plane. Leave it the length it came when it was new.

CGr.

RE: Where to run antenna wire?
 

I had the same question last week, here is my thread. There are a couple examples of tensioners in here too. I ran mine straight out the bottom and used scotch tape to hold it to the fuse. Be sure to leave some slack inside the radio area to move your receiver around when needed and so that it won't pull it loose from the receiver.[sm=thumbup.gif]

http://www.rcuniverse.com/forum/m_7611555/tm.htm

RE: Where to run antenna wire?
 

Yes and no....

You can put a 90 degree bend in the antenna w/o appreciable attenuation of the received signal.

You can also place a bend in the wire that reverses the antenna direction back, provided that you leave a sufficiently wide effective loop.

As you've stated you do not want to fold the antenna back so that the two lengths run parallel to each other closely, however if the lengths are say 3+ inches apart or more there is no problem. BTW: I do this all the time.

Coiling the antenna does NOT effectively shorten it, and is purposely done with base loaded antennas and some "short" antennas, however it does reduce the area that is most sensitive to the signals. Done properly a "coil" or a base loaded antenna only shows a negligible loss of signal strength if the effective uncoiled length remains the same.