Radio Propogation of Transmitters

Jan 1, 2012   //   by Nigel   //   Tech Info  //  No Comments
  • Radio Propagation (35 Mhz and 2.4 Ghz)

 The 20 degree cones from the ends of the transmitter aerial are the areas of poorest radio signal radiation. (and reception: 2.4Ghz).

The ratio of signal reduction compared with the maximum signal off the sides of the aerial is up to 10 to 1………….with more, or less  depending upon local conditions which are affected by damp ground and reflections from nearby vehicles and structures.

This is a tested and proven FACT…………..whatever frequency you use !

So even with 2.4 Ghz transmitters fitted with stubby antennas, NEVER point the end of the antenna directly at your plane ………..especially at a distance. It also has to receive the return data signals from the plane to maintain it’s bind  

I have seen many flyers using the transmitter with the antenna folded flat along the top…………This will work fine as long as the transmitter is pointed directly at the plane, BUT, when the plane is oriented to one side or the other at a distance, you’ll have the TOP, or worse, the folded BASE of the antenna pointed at your plane………..with a significant reduction in radio range………..and the loss of receiver binding, and, your model !!

Try a range check with the transmitter aerial pointed directly at the plane.

(One section of aerial: 35 Mhz, or reduced power: 2.4 Ghz  )

At about 100 yards (95 metres) distance, slowly lower the transmitter to within one foot (300mm) of the ground…………with the aerial still pointed directly at the plane …………..this will attenuate the transmitted signal and save you walking too far.

How far do you get before the receiver loses it’s signal ?………Do you get an immediate return of control when the aerial is re-oriented at 90 degrees to the plane ? Just by moving the transmitter very slightly, you will gain and lose the bind. Even with the latest equipment, it can take a least a few seconds to recover and re-bind the data link.  

Please look at out the following Video, supported by Spektrum / Horizon Hobby. The two presenters appear to be a bit “Goofy” but their advice as regards radio installation and use is good information, although, they do forget to mention that the “receivers” are also transmitting data back to the “transmitter” all of the time in order to maintain the “bind” or  “Lock-On” .

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No Signal = No Control

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