As a general rule, if you don’t have information on how a device works, you’ll need to replicate it in its entirety. If you cannot replicate an object completely, stop wasting your time and resources on that idea.

If you’re looking at a car but aren’t a mechanic and don’t have access to any books on automotive design, don’t just throw the engine out. The car won’t work without an engine. The people who put it there weren’t stupid. If you want to replicate the car, you must replicate the entire thing. If you don’t have reliable information on how it works, you’ll need to reproduce every single detail precisely.

True story: When the Soviets captured a B-29 bomber in 1944 and attempted to replicate it, they found a small hole in one wing. Assuming it was intentional, they drilled a hole in the same location on every wing of their copies - the Tupolev Tu-4.

Stop trying to invent things the DoD doesn’t use. Pick something the DoD actually uses and replicate it in its entirety.

You want an EMP-proof bunker? Fine. Start with quarter-inch thick steel plates welded together with no gaps. Add plenty of reinforced concrete on top.

You want EMP-proof radio communications? Fine. Start with a shipping container. Fill it with whatever electronic equipment you want. If you have that much gear, it makes sense to include multiple redundant transmitters and receivers with hot-swap capability. If you only have a small amount of equipment - say, what fits in a Faraday bag - you won’t be able to communicate with anyone anyway. Multiple redundant systems will cost more than the equipment you’re trying to protect, making them economically pointless.

Ham radio will be useless for long-distance communication without repeaters. If your family or friends are within walking distance, you can simply walk to meet them. No Faraday bag is necessary, because most radios will likely survive an EMP anyway. They’ll work - but they’ll still be useless.

Here’s an actual photo of a National Public Warning System broadcast station. Essentially, it’s just a shipping container: https://www.fema.gov/emergency-managers/practitioners/integrated-public-alert-warning-system/broadcasters-wireless

Faraday bags are marketed specifically to hobbyist preppers. My trust that they work as advertised is exactly zero. I see all the hallmarks of snake oil in this product.

Copper has 4.4 times the conductivity of steel and 1.7 times that of aluminum. Copper is an efficient conductor per unit of volume. However, aluminum’s density is about 3.3 times lower than copper’s, making aluminum roughly twice as effective per unit of weight.

The huge difference lies in cost. Faraday bags made of copper mesh are marketed to hobby preppers, while aluminum foil is a mass-market product - at least two orders of magnitude cheaper. You can even buy metal pots at the dollar store.

I’ve spent a good part of my life around equipment specifically designed to withstand EMPs, and I’ve never seen a Faraday bag.

I’ve worked in the telecom industry, which is perpetually cash-strapped. Cell phone towers are not EMP-proof. Your phone bill would need to at least double if you wanted cell service after an EMP. Telecom companies can’t provide EMP-proof service out of goodwill.

I’ve also worked in the banking industry. They’re comparatively well-prepared for an EMP in the sense that they won’t lose their money. However, your access to your money depends on the functioning telecom infrastructure - and that won’t be available.

Nothing you could possibly put into a Faraday bag would be useful in a real emergency. Cell phones won’t work. Meshtastic networks are too sparse to function without the Internet.