Wireless RF Distribution in Buildings Using Heating and Ventilation Ducts

An alternative method of distributing RF in buildings is proposed in which the heating and ventilation ducts are used as waveguides. Because of the relatively low waveguide loss, this method may lead to more efficient RF distribution than possible with radiation through walls or the use of leaky coax. Further, the use of existing infrastructure could lead to a lower-cost system. Initial experimental results are presented that demonstrate duct-assisted propagation between nearby offices in a university building. An example method is described for obtaining efficient coupling between coax and 8"x12" rectangular duct over the 902-928 MHz ISM band.