| 摘要 |
This invention makes it possible to communicate through solid non-metallic walls or ceilings with low microwave power levels. RF beam forming couplers are driven by common LAN (Local Area Network) circuits. For connection to a LAN segment at the other side of a wall or ceiling, transceiver 4 transmits data modulated microwave RF to coupler 6 through a directional step attenuator 10. The reduced signal is received by the coupler system at the other side with a power level low enough to eliminate wireless detection from the outside. However, the directional step attenuator on the receive side reduces the signal power only by an insignificant amount due to its low directional losses during receive signal flow. Each coupler's geometry is minimizing the radiation exposed material volume by RF field concentration, therefore, enabling transmission through thick concrete walls at microwave frequencies without compromising privacy. When used as wireless access point, coupler transmits through a floor to wireless devices below. The preferred embodiment operates in the 5-GHz ISM band. |
