Some flying from yesterday I still have no idea what my range actually is at this point but I can go plenty far and high
To break things down and hopefully make it a bit more clear, there are two different signals going on here basically completely independent (in 99% of cases)
There is a control link signal from your transmitter/controller (the thing you push sticks on) and the receiver for it on the quadcopter, this carries the inputs from the sticks moving up to the quadcopter, this is called the "control link" it is 2.4GHz typically and is being tranmistted from the thing you hold up to the quadcopter in the air.
Completely separately from that you have a video transmitter (on the quadcopter transmits video back down to you on the ground) so they are basically two one way transmit/receive things going on. This is usually 5.8GHz frequency or thereabouts.
One is Control-Link from hands/controller to quad other one is Video-Link from Quad down to you on the ground (with receivers).
Regarding dual antenna if they packaged the video receiver and the control link in one then you might have one 2.4GHz antenna and one 5.8GHz antenna sitting next to each other, the other reason you'll see two antenna like on my receiver is so if one antenna isn't getting a good signal but the other is then the receiver module can switch on the fly to the antenna getting the better signal and can amplify that. The "diversity" is on the receiver side of things (could be video-link or control-link receiver either could use diversity or an antenna array of some sort to capture the signal).
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Also to try and clear up earlier discussion there is frequency and then there is amplitude when it comes to transmitted radio waves or electromagentic waves of any sort. Lower frequency has longer wavelength and typically "goes further" (think of AM radio or HAM radio that can be bounced across the ocean off the atmosphere at the right times
), but we are limited to using certain bands/frequency ranges that the gov leaves open and doesn't use for emergency services or other critical infrastructure stuff, or license out to make some $$$
The amplitude on the other hand is just the "loudness" of the wave or how much force is behind it rather than a change in the length of the wave, but both can effect what a wave will penetrate or how far it will travel (from my still rough understanding though the frequency can make a far bigger difference if going for much more range compared with just amplification at a given frequency).
A picture to go with my thousand words