NOTE: The result of extending the antenna to one wavelength did not improve results. After reading a couple of articles on antenna design (Understanding Antenna Specifications and Operation, Antenna Design and RF Layout Guidelines). I may attempt to shorten the wire by small amounts and see if, by trial and error, I can maximize the output range. I would suggest that anybody attempting to modify their antenna should do a "walk" range test with the factory setup first. "Walk" test results for the Syma X5C and the Syma X8G are given next.
Range tests performed by activating the Quadcopters with a controller, setting throttle on lowest setting, leaving the controller on the mailbox, and driving my golf cart away down the road while holding the Quadcopter. When the copter blades stopped, I noted the location. I did separate runs for antenna positions toward and perpendicular to drone.
Google Earth was used to determing the straight line distance. The longest measurement was around a curve in the road with trees between the controller and drone. I would suggest not pushing the maximum limit on any measurement as I noticed some deviant behavior before reaching the limit. The limits given are the distances for which the copter completely lost communication with the controller and all rotors stopped.
Syma X5C with stock controller antenna sans camera: Pointing toward - 170 m; Pointing perpendicular - 120 m
Syma X5C with modifie controller antenna as described above sans camera: Pointing toward - 120 m; Pointing perpendicular - 120 m
Syma X8G with stock controller antenna sans camera: Pointing toward - 415 m; Pointing perpendicular - 298 m
Syma X8G with stock controller antenna with camera: Pointing toward - 300 m is the maximum "safe" distance measured.
Conclusion: Modifying the stock transmitter antenna may not be beneficial for increasing flying range as the circuit board, and even the plastic copter housing, affects the ground plane of the antenna. I would like to see some similar "walk" tests of controllers modified with 2.4 GHz router antennas. Folks should report their results with there published modifications. My stock X8G has a "safe" range <= 300 m. Finally, I believe the Syma X8G has a very good range for a low-medium priced Quadcopter. At 400 m, it would be out of sight for most folks.
This describes an easy method for extending your Syma X5C Quadcopter's range by modifying the antenna of the controller. At issue is impeadance matching so the power output for the transmitter is maximized. I plan to do a "walk" test on both a modded and unmodded controller on the same quadcopter. I also want to check directionality so that the signal is not lost when the modded controller is moved around relative to the copter. I will report the results soon. There are several videos available on the web which describe similar techniques and also how to take the controller apart. Therefore I will not go over taking the controller apart nor putting it back together. In the picthure below, are shown the items you will need to make this hack. The tools you will need are a small Philips screw driver, small hobby saw, a soldering iron, a metric ruler, wire cutter and stripper, and a heat gun (the heat gun makes a much nicer finished look).
1. The items shown are a length of #18 insulated copper single-strand wire longer than 12.5 cm.
2. A black Pilot "Better Grip" pen.
3. Piece of one-quarter inch black heat-shrink tubing about one inch long.
4. Piece of three-eights inch black heat-shrink tubing longer than three inches long.
After taking the controller apart, remove the small stock antenna and solder one end of the copper wire in its place. Measure and cut the wire so that it is 12.5 cm (full-wavelength), 6.25 cm (for half-wavelngth) from the solder point (for 2.4 GHz). Next, cut the very tip of the faux antenna off, run the wire through the faux antenna, and reassmble the controller. Make the wire as straight as possible. Now take the Pilot pen apart keeping only the hollow case which will be used to extend the stock antenna to hold the new antenna wire. Cut the case long enough so that the closed end is beyond the antenna tip. Use the 1/4" heat-shrink tubing at the joint where the original antenna and pen casing meet. You may have to stretch the 1/4" tubing with needle-nosed pliers prior to shrinking with the heat gun. The final step is to shrink the 3/8" tubing over the entire antenna making it stiff. The final result is shown below.
If you have results you would like to share, contact me at gmail-dot-com as TimberRock.