Ice Radio Products

Modern Lightning Protection for Radio Facilities: Control Lines

Control lines are essential for antenna switching, monitoring, rotation, and telephone service, but they also introduce multiple entry points for damaging lightning-induced currents. Additionally, these lines can couple with transmitted RF energy, causing interference at ground level.

Proper lightning protection and RF decoupling are critical in station design, and the best solution lies in the bulkhead grounding system. Protection devices are most effective when lead lengths to ground are minimized. Use #2 copper wire or larger for optimal grounding.

Key Control Line Protection Tips:

  1. Map the Layout

    • Create a detailed map of control lines, including lengths and destinations.
    • Mark lines longer than 25 feet for overvoltage protection.
    • Update and date the map regularly for reference.

  2. Bundle and Separate Lines

    • Bundle control lines together but keep them separate from RF coaxial cables to avoid coupling.
    • Run RF cables up one tower leg and control lines up another to reduce interference.

  3. Use Inductors for Protection

    • Install inductors (100 µH or more) in control lines to slow incoming surges and choke RF signals.
    • Match the inductor wire size to the control line.
    • Bypass inductors with 1,000V-rated capacitors on both sides for additional RF decoupling.

  4. Install Line Protection Devices

    • Use rotator/control line protectors (e.g., Models 348 or 349) to shunt overvoltage to the grounding bulkhead.
    • Ground all control lines at a single bulkhead point near the equipment.
    • For elevated stations (second floor or higher), route lines to ground level first for protection, then lead them upward.

  5. Conduit and Burial for Added Protection

    • Install control lines in conduit or buried plastic pipe to protect against weather and animals.
    • This not only enhances durability but also improves the facility’s appearance.

By implementing these measures, you can safeguard sensitive equipment from lightning damage and RF interference, ensuring long-term reliability for your radio facility.