I've been following drone comms since they arrived. I wodered back then why we didn't see drones flitting onto football stadia, or the 2012 Olympics, by people wanting video. You can't shoot them down unless it's indisputably "safe", and anyone with a soldering iron can change the radio. It's interesting, sometimes in a morbid sort of way, to see where designs have been going, for quite some years now.
It's not at all easy to "jam" one which is designed to resist the manufacturers advertise the methods, and of course some military would go further. They don't need to transmit continuously so you can't easily monitor them, the frequencies they use don't have to comply with standards, and those hop about - the drone picks a clear band. The transmission power you would need to swamp a wide comms band is immense compared with what the drone needs to communicate. The drone is moving quite fast, which the jammer isn't, flying low enough to obstruct the jammer signal. They would use GPS if it's there, which it usually is, because that's not easy to jam and reception is highly directional. If GPS is not there they can use other means to navigate.
The small drones are like a fly in a barn - what do you use to shoot them down? Imagine trying to use a machine gun... The bigger ones are easier to shoot down, but they have the irritating impertinece to still blow up, and near to you if you're on the ground.
One feature drones have is to be hugely helped by mass production. If the integrated electronics production is within scope for the drone maker - (less so for Russia than US or the Far East), then it's just a clever pcb. Vast numbers can be used at little cost. One side can send large numbers, and the other can't stop em all. SAy 10 - 100 to get pictures, 10,000 to kill all the people in the open. It's easy enough to target warm things which are moving about.
A "disruptor" in the R-Uk scene so far has been the cheap defensive weapon. The NLAWS type are a mere £20k each. A-A Stingers cost about £70k. The things rarely miss, and though improved, they're 40 year old technology. Russians have slightly better ones - Iglas.
Now combine the above. If the western best munitions can be got to where they're really needed, perhaps it really will be possible to stall the Russians' advance. The US artillery pieces (The 155mm ones) outrange the Russian ones by a good margin. And they're clever of course. It's standard to work out where a ballistic shell has come from, using radar-tracking of the incoming path. So you fire one back, up its muzzle, so to speak. Putin did pick those out as something he would think was unfair...
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Quite a good site for the status of the conflict, Moldova, etc, not too much spin:
https://www.19fortyfive.com/