When considering the DAS, which component acts as a bidirectional antenna?

Multimode optical fiber carries modulated light signals used for fiber-based DAS transport backhaul and has no RF radiating or receiving properties.

Radiating coaxial cable has periodic openings or slots engineered into the outer conductor that intentionally allow RF energy to leak outward for transmission and to couple inward for reception, creating a distributed antenna effect along the full cable run. This bidirectional radiation property makes it functionally equivalent to a series of closely spaced antennas oriented in both directions, which is the definition of a bidirectional antenna in a DAS. It is the standard solution for extending two-way radio coverage in environments such as tunnels, parking structures, and large buildings where discrete antennas are impractical.

Shielded twisted pair cable is designed for structured cabling data and voice applications and cannot radiate or receive RF signals in a DAS.

Single mode optical fiber carries optical signals over long-distance fiber DAS transport links and does not function as an RF antenna.

Screened twisted pair cable is used for structured data cabling with EMI shielding and has no role as an RF antenna component in a DAS.