The interesting part of this, I can use the radio to listen to a storm even though it is not producing Cloud-To-Ground (CG) lightning. The radio can also recieve the Cloud-To-Cloud static discharge as well. The only problem is the radio and antenna of the car is Omni-Directional (I receive the signal from all directions), so I cannot use the radio to determine where the stronger storms are around me.
I started looking online for Lightning Detectors, and what commercial products I found were either expensive, not informative. There are some portable lightning detectors on the market that will estimate the time a storm will arrive, based on the same AM Pulses. Other detectors are dependent on a computer with expensive software, and it uses other similar stations to triangulate the location of a lightning strike.
I started thinking about Doppler Shift Radio Direction Finding, and even asked a local Elmer if I could use the same technology tuned for the 144MHz band on the 500KHz lightning pulses. This was ruled out due to the need to adjust the antenna size and spacing to achieve what I wanted to do, making this a non portable project.
|Directional Lightning Detector|
below my mobile HAM Radio
APRS and NOAA WX
I came to the conclusion that I could build four Lightning Detectors, and build a four element antenna so I could determine direction of lightning activity. I found some diagrams online for Lightning Detectors, and placed a parts order with Mouser.
I started building the recievers into a box, and used a 5v regulator for each receiver. I had some issues with two of the receivers, and that required some troubleshooting and replacing a few blown components. I also noticed some interactions between the receivers while testing, so I added a diode to the ground of each reciever and that seemed to isolate the recievers from each other.
|Built receiver box|
|Bearing indication of lightning|
Next, I started building a simple antenna array for the recievers. I used a tupperware container, and wrapped cardboard with aluminum foil. I double stick taped the foil so it would stay on the cardboard. I created a small channel under the bottom square, so I would not damage the RG-174/U Coax. I placed two hard drive megnets inside the case, under the base square of the antenna, so I could Mag Mount the antenna to the top of my car.
|Ground wire, and magnets on bottom|
Before securing the base of the antenna to the case, I poked a hole in the center of the case, and ran a ground wire. This would allow the antenna to use part of the car as a ground plane. This might not be the most efficient design, but I am not transmitting with this unit, only recieving.
Here is the completed antenna. Now if I can just get people to accept it, instead of yelling at me, while driving 70 MPH, that I "have something on the roof". I think a gray can of spray paint should do the trick.
Now if I can just get a few thunderstorms in the area.