A technical paper on a distributed sensor network for large countries:
Part 1. Illuminators
Take a Shahed-135 style-drone, slap a turbocharger on it so they can loiter at 10km altitude. Uprate the brushless generator so it can draw about 2kw from the motor when required. Add wheels and use a version of the MD-55 that has a 1000hr TBO.
Take the existing SDR radios and add an amplifier capable of generating 2kw of RF and put a FM transmission antennae across both leading edges of the wings. Upgrade the IMUs and flight control software to be able to station keep within a 5 meter radius at a precise time.
Part 2. Dual purpose ground stations
Stick a FM receiver on top of every one of your cell towers. 5g networks are great because they have 100ns sync requirements between base stations, so you now have a very consistent time signal across your huge country, which is crucial for 4.
Part 3. Block derivation
Due to the distributed nature of the network, you cannot have secrets on your reciever nodes.
Nodes use certificates to verify signed blocks from authority nodes. These blocks are a highly compressed set of seed data from which any node can derive the source location, frequency, and exact timing of the expected illuminator pings over the next 60 seconds. Airborne assets have their seed data (that specifies their loiter area and emission schedule) pre-encoded on the ground before takeoff. The authority nodes generate the seed data and then compute and broadcast blocks at 60 second intervals.
Part 4. Interferometry
Using the precise timing across all nodes in the network, along with the derived transmission schedules, you can do interferometry across all your ground nodes to track returns from enemy aircraft that are reflecting transmissions from your airborne nodes.
How it works:
When you suspect that the enemy is sending in a wave of aircraft, you launch the illuminator fleet. Because the illuminators are so inexpensive, you can have 1000 of them across the country. The illuminators move in a random search grid, transmitting unpredictably, across a wide frequency range, using a swept radar chirp that helps with ranging information to receiving stations. The illuminators are RF silent other than when they blast radar pulses. Some illuminators stay dark for hours, some transmit constantly. You can run simulations to come up with optimal transmission schedules.
Because the illuminators are airborne, they are hard to target. They are inexpensive, so shooting them down with standoff missiles will bankrupt the attacking nation. They are also readily replaced, and don't require any expensive ground infrastructure, just a shed, a flat field and a barrel of mogas. Your detectors are passive and networked by buried cables.
The detection of radar returns is possible through large-scale interferometry, because you have perfect information on the location (lat,long,altitude) and transmission characteristics (power, frequency, sweep, duration) of the illumination pings. These pings are in the FM wavelength because modern stealth aircraft have a much larger return at these longer wave lengths. FM is not typically used for radar because it gives very inaccurate angular and ranging information. Because of your precise timing across the network, you can use the block derivation schedule for signal rejection, and then time of flight to identify potential matches.
All these potential airborne matches are then sent into the network, where they can be fused together to generate guidance data for defensive system that do not require an active illuminator on the launch vehicles.
I think the idea of a country being able to be bombed relentlessly from 40,000 feet with no way of defending itself from aggressors is grossly unfair, and I technology such as this will help all the countries of the world defend themselves from rapist presidents and genocidal zionists.
