Fiberglass Radomes

Diamond Antenna prone to lightning strike?

August 19, 2010 seems like a perfect day for me. Waking up early for work and packing some foods and snacks preparing for another tiring day from morning until the evening of the day.During lunch break at the office, I already noticed the sudden change in the weather outside. Rain drops started to fall and the wind was somewhat violently blowing in all directions. I got wet because I had my lunch outside without an umbrella. I was waiting for the time at the office to end. When 5:10 pm came, I prepared all my stuff and left the office. Rain keeps on falling and some streets in Pasig area while on my way home to Marikina were already flooded. I heard over the news that almost 60 percent of the roads within Metro Manila are already flooded.

The same day, I went to our Church for the worship service. For me, the day was just turning out to be complete the way it should be. After the worship service, I head straight at home to reward myself for a lengthy rest to replenish in preparation for the next day. As soon as I step out off the car, my brother approached me and said that something terrible had happened. He said that our TV, computers and telephone lines are not working. And then he followed up to me that a lightning strike struck, and directly hit my radio antenna. I was shocked and couldn’t really believe it. I thought my brother was just kidding, but when I checked our TV and computers, all turned haywires. I felt so sad and asking my self how could this happen? Our home is not the only one in the area. Plus the fact that my radio antennas are not the highest object in our subdivision. Here’s what really happened after my thorough investigation.

At around 5:30 pm. Lightning strikes are everywhere in our area. I could still remember that I unplugged the RG-8 COAX cable  PL-259 connector before I left home for work, one from my ICom 229H VHF radio and the other one from my ICom V8000 VHF radio. The antenna connected to the ICom V8000 was the Diamond Antenna F23H VHF while the antenna connected to the ICom 229H was the Diamond Antenna CP22E. The Diamond Antenna CP22E is relatively higher than the F23H at around 5-6 feet. The Diamond CP22E has been in service for more than 10 years already unlike the F23H which is just a 2 moths old, I bought it at CQDX in Quezon City June of the same year. The two diamond antennas were 6 meters away from each other on our roof. CP22E placed higher than the F23H. The diamond CP22E has a mast of 10 feet and the F23H is elevated by a 4 feet mast.It was the F23H. Even though it was relatively lower than the CP22E, it was the only object which was hit directly by the lightning strike. The super power current and electronic voltage probably jumped across nearby power lines. So much powerful, sophisticated equipments such as three unit computers and one television were damaged in our home. One of our neighbors actually thought that their house too was hit by the lightning strike. But in my mind, the direct hit struck to my antenna. Our neighbor also said that their TV was also damaged. See the pictures of the Diamond Antenna F23H after getting hit by the lightning strike.

Diamond F23H after lightning strike – Parang Marikina, Manila Philippines

After that, I did some research about lightning strike. How it behaves and what is the cause of ground object getting hit by lightning strike specifically radio antenna. Because, I don’t want it to happen ever again even in my dreams. No way! I wouldn’t risk anyone. Here’s what I found out.

 Is it true that fiberglass antenna are prone to lightning strike? Like the F23H?

144MHz antenna turned into pieces of sticks

Diamond Fiberglass Antenna

 

The answer is Yes. This is based on my research. Others may disagree but based on my actual experience, I believe that there’s a scientific explanation to it.

The diamond F23H is made up of fiberglass tubes. During thunderstorms or typhoons or even when wind is blowing so fast with high level of intensity, the wind and the fiberglass surface creates and building an invisible static electricity around the antenna due to air to fiberglass surface friction. The static exlectricity build-up is getting bigger as the wind continues to blow. This static electricity is what they call static electricity corona. As such attracts lightning to discharge directly to it. Lightning searches for the easiest or shortest path to discharge to ground earth. Though my diamond F23H antenna was not the tallest object in our area, and in terms of proximity, other higher objects are just stone throw away with it, lightning got attracted by the formation of the static electricity corona and inevitably, my F23H was directly hit by the lightning strike. How about the diamond antenna CP22E?These are the lessons learned  :)

1. Ground your antenna mast

Ensure that your antenna masts are grounded properly to the soil. Use at least 5-10 feet grounding rod.You can connect multiple ground wires to a single rod, however it is ideal to have more grounding rods in different areas within your lot area. Use 6-8 TTHN copper wire to ground your antenna mast.

2. Use surge protector devices

All your feed lines should have a surge protector.

Telephone lines
VHF Radio coax cables
Cable TV
Power lines
(Any other lead wires that came from an external source or outside your house)

For my 2 VHF radios, currently, I am using the Diamond SP1000 static discharge unit. It actually helps discharge static electricity build up on my antenna at the same time, it will automatically discharge electricity to earth ground in the event of a direct lightning strike. Thus preventing damage to home appliances.

3. Unplug power cables and antenna cables from your equipments during thunderstorms or when lightning is obviously striking.

If you have questions, please leave your comments here.

In between the two diamond antennas, what was hit by the lightning strike? Guess what? The other antenna which is the Diamond CP22E was not affected at ALL. No scratch, no burn, no nothing. This VFH radio antenna is made up of alluminum tube. Again, based on research, this materials generates less static electricity caused by air friction.

Tips on how to reduce the chance of getting hit and prevent wide scale damage to your electronic equipments at home.

Antenna Ligtning incident

 

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