Ice Radio Products

Modern Lightning Protection for Radio Facilities: RF Entry Ports

Lightning is one of nature’s most destructive forces, comparable to a powerful explosion. If your antennas are elevated and exposed, lightning strikes—or even light rain—can induce dangerous voltages. At the I.C.E. factory, a technician received a shock from a 160-meter dipole during a rain shower, demonstrating how thousands of volts can accumulate even without direct lightning strikes.

Proper lightning protection for radio facilities using coaxial feedlines is essential. Here are key recommendations to safeguard your equipment:

Essential Lightning Protection Tips:

  1. Route Coaxial Cables to Ground Level First

    • Never bring coax cables directly into a building at elevated points.
    • Always route cables to ground level before entering the equipment area.
    • This prevents lightning currents from passing through sensitive equipment on their way to ground, reducing the risk of severe damage.

  2. Ground Coax Shields Immediately

    • Ground cable shields as soon as they reach ground level.
    • Use commercial shield grounding blocks or create your own solution.
    • Up to 80% of lightning energy often enters through the shield, making this step critical.
    • Multiple grounding points (e.g., at the tower base and building entry) add further protection at minimal cost.

  3. Install Blocking-Type Lightning Arrestors

    • Avoid basic gas-discharge-only arrestors; they activate too late, often after damage occurs.
    • Use blocking-type arrestors with no DC continuity from input to output. These handle current more effectively and protect against induced voltages.
    • Gas discharge tubes, rated for 20,000 amps, can fail under prolonged strikes or slower blasts, making them unreliable as sole protection.

  4. Establish a Bulkhead Grounding System

    • Install a grounding bulkhead near the radio equipment, minimizing the distance from the coax entry point (ideally less than 1 foot).
    • The bulkhead can be a metal bar, sheet, or heavy wire. It serves as the RF neutral point for filters and protection devices.
    • Short, direct ground leads improve performance far more than wire thickness or material type.

By following these guidelines, you can significantly reduce the risk of lightning damage to your radio facility, ensuring greater longevity and reliability for your equipment.