Shop our Airplanes Products Shop our Surface Products
Thread Tools
Old Dec 25, 2011, 07:20 PM
rcwatchman is offline
Find More Posts by rcwatchman
Registered User
Joined Dec 2011
77 Posts
Antenna length??? Please respond!

I know that the length of an antenna on a transmitter is critical. But on a 2.7MHz heli, being on the receiving end, does the length of the antenna make it better or worse for drop out of the signal?
rcwatchman is offline Find More Posts by rcwatchman
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 25, 2011, 07:55 PM
Username> is offline
Find More Posts by Username>
Suspended Account
Joined Dec 2007
1,102 Posts
Yes, antenna length is part of a " resonant circuit ", so even on receive a wrong length or untuned antenna will affect range.

It's been a while since I was into electronics, but iirc, here is the calculation method;
Cb band is 27Mhz (11m band), and since radio waves travel at 300,000,000 m/s, to find the optimum aerial length for cb you would use 300000000/27000000= 11. Hence the reason you see huge cb antennas.
For microwaves like our tx/rx (2.4Ghz) you would calculate 300000000/2400000000= 0.125 (12.5cm band). Hence the reason you see very short antennas on the latest technology.
Antennas can also be resonant and work on 1/4 waves, 1/2 wave, 5/8, et al, so a 1/4 wave antenna for 2.4Ghz would be 0.25 * 12.5cm = about 3.1cm
Hope this helps.

I used to do lots of repairs on radio equipment but I still know a fair bit about antennas, rf, etc..
Username> is offline Find More Posts by Username>
Last edited by Username>; Dec 25, 2011 at 08:06 PM.
Reply With Quote  (Disabled)
Old Dec 26, 2011, 02:54 AM
abenn is offline
Find More Posts by abenn
Registered User
Letchworth, Great Britain (UK)
Joined Jul 2004
13,430 Posts
As damo666 says, reciever antenna length is critical. But that's for optimum reception so, if you're flying at a distance, like outdoors, you need to let the full length dangle below your heli.

If you're flying close up, though, especially inside a house, you can wrap the antenna around a drinking straw (anything non-conductive) to make a neat coil and fix it to your skid or boom where it won't get in the way of anything. With my Twister Bell I lace it back and forth within the lattice tail boom a few times instead.
abenn is offline Find More Posts by abenn
Reply With Quote

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion why my antenna have wrong length modelerchina FPV Talk 5 Feb 26, 2012 09:44 AM
Question To upgrade a low budget or not? Please respondů rcwatchman Electric Heli Talk 4 Dec 11, 2011 12:18 PM
Question Rebuilding stock, please respondů rcwatchman Electric Heli Talk 3 Dec 10, 2011 09:46 AM
Discussion Anyone with a champ please respond! rlpolo Beginner Training Area (Aircraft-Electric) 6 May 18, 2011 02:54 PM
Discussion Berg-5*DSP II (antenna length/ gauge?) RBaptist Castle Creations 0 Mar 27, 2011 06:52 PM