Best set up as a mesh network of Linksys routers (the Linux models) or modified cellphones/tablets. Every person to set up a node would extend the network. External antennas are simple to build for these frequencies...best to put the device in a watertight container at the antenna to avoid feedline loss. Pipe DC up to it with a twisted pair.
An easy to build discone would be a good choice for the antenna as it is so easy to make and tolerant of mistakes as it is so broad-band.
Modified old cellphone/tablet/router up 30ft on a pole with a discone and you extend the network for miles. Just putting the device in a plastic bag and feeding power to it would extend the network a mile or so if placed in a high spot like an attic or chimney.
Everyone has a few old cellphones and chargers.
Now your getting to an ad-hoc wireless network. Something that would draw a lot of attention from “them”. That is very interesting on a local basis though, in order to reach the BBS if the phone system is taken out.
The original idea was a way to keep communicating nationally if the “kill switch” happens. My idea is for FReepers to keep in touch and sharing information, not the general public.
That is why we would have FReeper HAMs able to send each other data packets and upload these packets on local BBS systems.