A device for transmitting electromagnetic waves through an aperture in a wall

A device for efficient transmission of electromagnetic waves comprising two layers of dielectric separated by a gap or space. The layers may be uniform or laminar, orthogonal or non-orthogonal to the direction of wave propagation, and made of Teflon, quartz, polypropylene, and the like. The preferred distance between layers is an odd multiple of quarter wavelength in the environment between the layers. The preferred thickness of the layers is an odd multiple of half of the effective wavelength for the layer. The device allows over 95% efficiency for transmission into a pressurized vessel for evaporation under high pressure and temperature and does not require a cooling system. The separating space may be connected with a pressure-sensing subsystem to monitor the device's integrity and shut down the system in the event of a breach. A sleeve connecting the device to the vessel may be coated with conductive material for improved efficiency.