Yeah figure there’s jammers but I wonder if they are throwaways? I’m thinking like maybe something the size of a spiral bound notebook with a small PCB at one end and an antenna running up the side or snaked along the surface of the page. Something easily carried in a bookbag, maybe even looks like a notebook at first glance. Or maybe they’re even smaller, like a coin, that can be thrown into the gutter.
Just saying it might make a good plot point for a book or movie to have a resistance group quietly bring in a few thousand of such devices and distribute them for random dispersion.
Antenna size is a big issue at these frequencies. I don’t think you can just use a tiny microstrip like with wifi. You probably need several watts of transmit power at least, which means you’re drawing even more than that from the battery and all your amplifies and stuff need to be able to dissipate heat properly.
Notebook-sized sounds plausible but coin-sized doesn’t.
For sure coin size doesn’t sound reasonable unless there was maybe some kind of wire loop antenna to unspool, and even then maybe the power draw is indeed too high to run off a watch battery.
I’m just thinking back to my Baofeng radio being not particularly large and the antenna pretty short. So maybe notebook size would be viable.
I’ve had one in hand(Not mine, belonged to a admittedly kinda paranoid mate) that was roughly the size of a pack of cigarettes, and blocked ALL phones and GPS for about 150-200m radius with the crappy 3-inch antenna. If you put something bigger on, you could get better range pretty trivially, a coil antenna the length of a notebook wire, you could get a decent radius. As Neito said, they overdrive the shit out of the antennas, because not just that the electrical noise isn’t a worry, it’s literally the point.