What’s the difference between passive and active distributed antenna systems (DAS)? We hear this question a lot in our field. To put it simply, a distributed antenna system, or DAS, is a clustered installation of antennas to boost cellular network coverage in areas with weak signal.

ACTIVE DAS

Active DAS simply means the components require a power source to operate. Building owners, property managers, and enterprise customers have a number of options when there’s a cellular coverage problem. Traditionally, so-called Active Distributed Antenna Systems (DAS) were the only alternative for many customers. These systems are expensive and take months to deploy, although for customers with capacity issues (think football stadium or airport) it is the preferred solution. Permission to connect to a carrier network is often a long, time-consuming process. For each additional carrier, the process has to be repeated each time.

Active DAS solutions are costly and can take several months up to a year to install. As a rule of thumb, any high-traffic building over 500,000 sq. ft. needing complete wall-to-wall coverage should consider Active DAS.

PASSIVE DAS

Passive DAS systems tend to use passive components like coaxial cable, splitters, and diplexers to distribute signal, and unlike active DAS, they use bi-directional amplifiers to re-broadcast signal from a macro cellular network using either an over-the-air donor antenna or a “small cell” from each carrier. This means that Passive DAS heavily rely on adequate signal from a nearby cell tower – a great solution for urban areas.

For a complete Passive DAS installation, the total cost is greatly less expensive than Active DAS and the time required installing ranges from days to a few weeks or months.

THE BOTTOM LINE

As a general rule, Passive DAS is the best choice for buildings up to 100,000 square feet, but can also be scaled upwards to 500,000 square feet. A Passive DAS is much more cost-effective and can provide appropriate cellular coverage in most commercial buildings.

Active DAS need be employed in complex, sprawling high-traffic areas like airports, stadiums, convention centers, and other structures over 500,000 square feet.