Which of the following is NOT a primary type of DAS antenna?

Directional antennas are a recognized primary DAS antenna type used to focus RF energy toward a specific coverage zone or sector within a facility.

Omnidirectional antennas are a recognized primary DAS antenna type that radiate signal equally in all horizontal directions, commonly deployed for broad in-building coverage.

Polarized is not a primary DAS antenna type - polarization describes the orientation of an antenna's electromagnetic field (e.g., vertical, horizontal, or circular) and is a property shared by both directional and omnidirectional antennas rather than defining a separate antenna category used in DAS architecture.

Radiation cable, also known as leaky feeder cable, is a recognized primary DAS component that continuously radiates RF signal along its length and is commonly used in tunnels, stairwells, and corridors.