The Reconstruction Finance Corporation (RFC) was established during the Hoover administration with the primary objective of providing liquidity to, and restoring confidence in the banking system. The banking system experienced extensive pressure during the economic contraction of 1929-1933.
Typical materials used for electromagnetic shielding include sheet metal, metal screen, and metal foam. Any holes in the shield or mesh must be significantly smaller than the wavelength of the radiation that is being kept out, or the enclosure will not effectively approximate an unbroken conducting surface.
if the ionosphere is so thin and has very low denisty how is it able to change the movement of shortwave radio? it isnt like glass or a mirror becuase it really isnt a solid like those are. can the ionosphere be some type of matter? sorry but everyone says radio waves bounce off the ionosphere but no one explains...