I have read a lot about carbon fiber and its effect on radio waves on several different forums, but no one seems to know how much it will effect radio transmission.

Today I cut some carbon fiber tube for the quad I am building, my first build, so I thought while I had these nice little tubes I would try an experiment. I don't really have a lab or any special equipment so I used what I had. I used my WiFi router as the transmitter and my smart phone as the receiver. I connected my phone by wifi and started walking away from my house until I lost the connection and marked that spot. Then I started walking back to my house until my phone reconnected and marked that spot.

Next I put the carbon fiber tubes over the wifi router's antennas they are set at about an 80 degree vertical V. the tubes are 25.4mm ID and 1.7mm wall thickness and completely cover the antenna and then some. Next I connected to the router with my phone and took the same walk again and marked where I lost connection and where I regained Connection. The signal is going through 3 interior walls and one exterior wall and the router is set at it's lowest power setting.  

 The bare antenna lost connection at 31.2 meters and regained it at 30.3 meters. The covered antenna lost connection at 29.2 meters and regained it at 27.4 meters. Of course this measurement was quite approximate but it seems that in this case the loss of distance was approximately 10%. Does anybody have any thoughts on this or any first hand data?

I don't think this experiment is a true representation of a real FPV flying situation is Carbon fibre might weaken the signal and not block it completely. The signal also bounces around the environment.

I think you need to measure signal strength (RSSI)... to maintain good control your RSSI has to be above certain level (I think it's at least 30% to 40%? my memory might be wrong), when you are flying, even a "one second" signal drop can cause crashes.

Connecting to the internet has too many variables. Would have been better had you just used WiFi Analyzer, its an android app. It will give you signal strength in one spot, then you could put on the carbon and get an instant readout.

Thanks for the feedback.  I took Bandook's suggestion and downloaded WiFi Analyzer and tried the experiment using my phone as a signal strength meter from a fixed distance.  With carbon fiber tubes over the antennas the reading was -84dBm.  With the tubes removed the reading was -80dBm.  I am just learning about radio signals so correct me if I am wrong, but isn't a -3dB change a cutting in half of energy? If so this would be much more significant change than what I had presumed. It of course still may not represent a real FPV flying situation very well.