Remarkable transmission of microwaves through a wall of long metallic bricks

The transmitted intensity of a microwave beam through a thick continuous metal wall will be effectively zero due to the almost complete exclusion of the electric field from the metal. However, it is shown here that by removing less than 20% of the wall material to produce a regular array of bricks, up to 90% of the radiation is transmitted, despite the gaps between the bricks being less than 5% of the incident wavelength. This result is attributed to the excitation of a set of resonant waves along the cavity length through the coupling together of surface-plasmon modes across its width. (C) 2001 American Institute of Physics.