View Full Version : 72mhz antenna extension?

23rd May 2011, 01:31 PM
I want to extend the antenna on my 72mhz corona rp8d1 to 1/2 wave. Currently it is 1/4wave.

I center the reciever in the front of my skyfun, and run the antenna down the left wing. I want to attach a new section of wire at the reciever, and run it down the right wing, reducing the amount trailing off the back of the wing.
Diagram of what I want to do:

Will this do the same thing as fully extending the original antenna to 1/2 wave? Or will the reciever pick up harmonics / multipathing by being centered in the antenna?

23rd May 2011, 01:32 PM
Good ques - as I've only seen the single antenna extended to a million miles. I never thought of it this way.

24th May 2011, 12:30 PM
No one has any idea if this antenna extension method will work or hurt my performace? I may have to do some ground testing on this and report back.


24th May 2011, 02:23 PM
Cool idea

25th May 2011, 10:23 AM
I discussed it with Alex a couple of months back and he wasn't too sure of the answer. Basically just said to test it and do a range check to compare the differences.

25th May 2011, 11:02 AM
hmm cool, thanks for the info. I guess I will have to try it and see.

28th May 2011, 01:32 PM
Did you try this yet ? My guess is it will not work as expected because you are now actually feeding two 1/4 antennas in parallel (impedance will be too low). A better match can be obtained by attaching antenna 2 to a ground trace on the receiver near the antenna output. This will give you a true, 1/2 wave center-fed dipole with approximately 68 ohms impedance.

28th May 2011, 07:42 PM
The only real GOOD way to test mods like this would be RSSI. I dont have that option right now, so ground range testing is my only option. I plan to try lots of combinations soon.

28th May 2011, 11:23 PM
There´s more about this here: