Multiband Distributed Antenna Systems Design Considerations

With the continued growth in the demand for in-building communications systems along with the high cost of installing a distributed antenna system (DAS), more people are installing systems designed to support multiple bands. Much of this is driven by the need to accommodate various services and agencies that have systems on different frequency bands. To meet local ordinances that require a building owner to provide in-building communications for the local fire and police, the system engineer may decide to “piggyback” the 800 MHz public safety system on the building owner’s existing UHF DAS.

 From a financial point of view, this arrangement looks great. It costs a great deal of money to pull hundreds or even thousands of feet of cable through a building, so the idea of maximizing the utility of the system, or perhaps sharing the cost, can be irresistible. There are, however, some pitfalls that can end up costing more in the long run if the DAS is not engineered correctly. The one thing more expensive than installing a DAS is installing another DAS later, along with changes to the initial system.