Originally posted by nimble
Look at this 5dBi Gain antenna.
You'll notice the coiling of the wire at a precise location which has the effect of actually creating two antennas in phase, which increases the gain. If the coils are not done right, the antenna is not in tune for a specific frequency. You might take this information as an opportunity to put in coils in just the right place and increase the range of your Spektrum... 
btw - your 2.5" antenna for the Nimble system would be right at the 1/2 wavelength. I'm not sure if the Spek system would be happy with that length, but theoretically it should be possible.