How to choose an external antenna for a BlueZoo sensor

BlueZoo sensors, whether hardware or software-only (e.g. BrightSign), require a Wi-Fi sensing antenna. This antenna defines the BlueZoo detection zone and is used to detect mobile phones in the zone.  This page describes external antennas for Black Panther sensors.  The differences with legacy sensors (e.g. White Rhino, Arctic Fox, Yellow Mongoose, White Stork, and AR150-series) are described under “Legacy Sensors” at bottom.

Connecting the External Antenna

Black Panther sensors are available with and without connectors for external antennas.  These connectors are reverse-polarity sub-miniature A (RP SMA) female connectors.  They accept 50-ohm external antennas with RP SMA male connectors.  Each sensor has one radio and two RP-SMA female connectors.

Detection Zone

These sensing antennas can be either an omnidirectional antenna (ODA) or a directional antenna (DA).

1. OMNI-DIRECTIONAL ANTENNAS (ODAs)
   The detection zone of any OD antenna approximates a sphere, centered on the antenna.  The maximum detection range of an OD antenna used with a BlueZoo sensor is over 300 feet.
   
   

The antenna internal to BlueZoo Black Panther hardware sensor (the standard sensor since Q1 2022) is an omni-directional dipole antenna.  External antennas are also often dipole antennas, but can either be connected directly to the RP-SMA female connector on the sensor, or connected via c coax cable.

The benefits of external OD antennas, compared to the internal OD antenna, include that the external antenna can (a) be placed outside an enclosure (i.e. Faraday cage) that might obstruct the incoming Wi-Fi signals and (b) have higher gain than the internal antenna.  A commonly used external OD antenna is a “puck” antenna, one example shown following.

1. DIRECTIONAL ANTENNAS (DA)
   The detection zone of any directional antenna (DA) approximates a cone, with its point on the antenna.  The maximum detection range of a DA can be over 300 feet.
   
   Like ODAs, DAs have various physical configurations.  A panel antenna, connected directly to the Black Panther sensor, is shown following.  DAs are very useful for limiting the detection zone to one side of signage or defining a small detection zone within a room where a sensor is mounted on a high ceiling.

Note that when a directional antenna is used for sensing, that antenna is generally not suitable for backhaul (because the access point may not be in view of the directional antenna) and another radio with an omni-directional antenna is required if Wi-Fi backhaul is to be used.  This radio can be attached via the sensor’s USB port.

Legacy Sensors 

Unlike Black Panther sensors, the Wi-Fi radios of legacy sensors cannot be multiplexed.   Therefore, if Wi-Fi is used for sensor backhaul, a second Wi-Fi radio is necessary.  This is true of the White Rhino, Arctic Fox, Yellow Mongoose, White Stork, and AR150-series sensors.