What is the difference between passive DAS and active DAS?

Passive DAS relies entirely on coaxial cable, splitters, couplers, and passive antennas to distribute a radio frequency signal from a central amplifier throughout a building. Because there are no powered components in the distribution network itself, passive DAS is simpler to maintain and generally more cost-effective for small to medium-sized buildings. However, signal loss increases with cable length, meaning passive DAS becomes impractical in very large or tall structures where long cable runs would degrade performance beyond acceptable thresholds.

Active DAS converts the RF signal at the headend into a digital or optical signal, transmits it over fibre optic cable to remote radio units placed throughout the building, and then reconverts it back to RF at each remote unit before distribution to antennas. This approach eliminates the signal loss constraints of coaxial cable, making active DAS the preferred solution for large hospitals, airports, convention centres, and multi-tower commercial developments. The trade-off is higher equipment cost and greater complexity in commissioning and ongoing maintenance.

A hybrid DAS combines elements of both approaches, using fibre from the headend to zone distribution units and then coaxial cable for the final antenna drops within each zone. In the South African context, the choice between passive, active, and hybrid DAS is governed by factors including building footprint, number of floors, target coverage reliability, operator requirements, and available capital budget. CT Communications and Maintenance conducts detailed RF propagation surveys and link budget calculations to recommend the most cost-effective architecture for each specific building.