Ported Coax ("Leaky" Cable)

This type of system uses a ported coax cable (typically buried) that has small holes in the outer shield of the cable. The purpose of these holes is to allow electromagnetic energy to radiate from the copper wire inside the cable, thereby creating an electric field in the vicinity of the cable. When an intruder or other object disturbs the field, a second parallel receiving cable senses the disturbance in the electric field and signals an alarm.

 

Principal Drawback

Subject to interference by sources of electromagnetic interference (EMI). Should not be used at electrical substations, around large electrical equipment, etc.

Other Shortcomings:

  • Very high component / installation costs
  • Nearby metallic objects, including metal fencing, can interfere with performance.
  • Sites with heavy snowfall are prone to unreliable detection.
  • Standing water over buried cables can generate nuisance alarms

Fiber Fence Advantages over Ported Coax Sensors:

  • Sensors do not require electricity
  • Not affected by electromagnetic interference (EMI)
  • Can be calibrated to eliminate nuisance alarms
  • Not affected by weather or standing water
  • No trenching required
  • Economical to purchase
  • Easy to install