How Do I Estimate Lightning’s Effects on my Radio Antenna?

Have you ever wondered how to calculate lightning-induced antenna-coupling levels for a specific radio setup?  How much energy could theoretically flow along my coaxial cable due to a nearby lightning strike?

Today’s highlighted article is a useful tool for anyone looking to make a assessment of a specific radio antenna’s susceptibility level when a lightning strike occurs nearby.

  • For example, how do you estimate the energy that might be coupled into the antenna from a nearby strike, and what levels of surge (Voltage, Current, and waveform details) should be expected further down the cable run?
  • Have you ever wondered how to calculate lightning-induced antenna-coupling levels for a specific radio setup? 
  • How much energy could theoretically flow along my coaxial cable due to a nearby lightning strike?

This NexTek technical article was published years ago, but the formulae and calculations given are still 100% valid today.

Typical Antenna ConfigurationWhat this article covers:

  • E-Field Coupling – The process of energy coupling into the antenna (from the surrounding charged air, aka the e-field around the lightning strike.)
    • Antenna Length and Operating Band
    • Location of Antenna
    • Pulse Characteristics (Risetime, Pulsewidth, etc.
  • Current Injection – The process causing energy flow due to nearby Current Injection into the earth/ground, which causes elevated ground potential and therefore current flow.
    • Location of Strike
    • Length of Cable Run
    • Current Injection Level
  • Overall Review – What these calculations mean, and what to do with the calculated values!

Please follow the jump to find the article and learn more about estimating the effects of lightning on radio antennae!


Learn More:

Article – Estimating the Effects of Lightning on Antennas

Other Resources:

Article – Get Grounded: Protection of Electrical Equipment Against Lightning Transients

Article – Selecting Coaxial Lightning Protectors



Product Spotlight: Lightning Arrestor for High RF Power Broadcast Applications

NexTek’s portfolio of available Coaxial Surge Arrestors contains one design that is uniquely suited for High RF Power radio applications. With Protection Voltage Ratings of up to 3500V and RF Power Ratings of up to 30kW+, the PTR7AF7AFxxK1 is uniquely suited to provide Lightning Protection for High RF Power installations.

radio-tower-5579_1920

The availability of 1400, 2500, and 3500V ratings mean that there is a specific configuration available to suit any RF Power level. Most coaxial Lightning Arrestors are available with ratings up to 800 or 1000Vdc and have Type N connectors as the largest available option, while the PTR7AF7AFxxK1 uses the following unique design features:

    • High Power Capable 7/16 DIN (female) connectors
    • High Power Capable Thru-Path Geometry which meets or exceeds 7/16 DIN RF Power ratings
    • High Voltage GDTs (1400V, 2500V, 3500V)
    • Multiple Gas Discharge Tubes (5 per arrestor) for a Long Lifetime
    • Replaceable Gas Discharge Tubes to allow periodic service or repair (as needed)

Don’t settle for Spark Gap protection for lightning & surge protection of your High Power Broadcast system. Old-school solutions like “spark gaps” can have Residual Voltage peaks of 10kV+, which can be enough transient energy to damage radio and amplifier outputs!

Instead, select the proper Protection Voltage based on your application details… then select the Protection Voltage which will allow normal radio operation and broadcasting, but is also low enough to turn-on quickly and limit Transient energy as much as possible during a lightning strike.

 
High RF Power Coaxial Arrestor - DC to 1GHz - Multiple Gas Discharge Tubes
High RF Power Coaxial Arrestor – DC to 1GHz – Multiple Gas Discharge Tubes
Learn More

For more information on how to make the appropriate calculations and select a Coaxial RF Lightning Protector; See the PTR7AF7AFxxK1 Product Datasheet for additional information, as well as a NexTek Technical Article published in Microwave Product Digest in 2011 entitled “Lightning Protection for High RF Power Applications.”

Product Information – PTR7AF7AFxxK1 Product Page (link)
Technical Article – Lightning Protection for High RF Power Applications (.PDF)
Coaxial Arrestor Home – Arrestor Products Page (link)