Â鶹´«Ã½

Wireless links carrying sound and vision around the house are unreliable:
low-power radio cannot get round corners, and infrared signals don’t pass
through walls. But Sony has an answer (WO 01/24407). It says devices that look
like front door security peepholes could channel radio waves and light between
rooms, without the need for any electrical power. A small hole is drilled
through a door or wall, and a metal tube is pushed through and capped each side
with a shirt-button-sized aerial. The diameter of the tube is tuned to the
signal wavelength and acts as a “waveguide” to feed…