Would cloth with metal mesh threads reflect the microwaves sufficiently?
That’s an interesting thought. Clothing made like that might possibly work to shield people from microwaves, or at least they would know microwaves are being focused if their clothing starts shooting sparks and catches fire like a jiffy pop popcorn pan when zapped (just an experiment when microwaves first came out.... :)
The ADS operates about 95 GHz while a microwave oven frequency is 2.45 GHz. The requirement is a mesh element spacing of one-tenth the wavelength or 1/ F times 300 million meters second, divided by ten to get a wire thread spacing in fractions of a meter. This works out to a third of a millimeter or thirteen thousandths of an inch for the ADS.
A salty water soaked fabric item (towel or blanket) may be the best option as a quickly improvised shield. The oven frequency is more penetrating and more easy to generate at high power levels, especially if not constrained to limit serious injury or death in it’s use such as is the ADS system.