Different antennas for different signals.
5.8ghz is probably going to be the cheapest but can get good range.
Most people use this in conjunction with 2.4ghz tx/rx radio as the signals don't clash. But there is 433 & 900hz I think which are used for long range along with 1.3ghz which can be used for either radio or video signal. I think I'm right to say all signals can carry video or radio, just some better than others, unfortunately your going to pay for the ones that are good. Looking @ something like a taranis with a module to use them.
RC model reviews has just done a new video explaining signal & gains.
If you haven't bought a Transmitter yet & you want range like 2km, then you may aswell get a taranis/crossfire combo.
And maybe a 1.3ghz vtx/rx setup.
Which has better penetration & distance over 2.4ghz & 5.8ghz
2.4ghz wins over 5.8ghz for fistance & penatration
in radio.
While 5.8ghz wins over 2.4ghz for carrying a video signal & 1.3ghz.
1.3ghz can carry signal further.