0
\$\begingroup\$

I'm working on a open-hardware wireless wind sensor. It's designed for being installed on mountains, where thunderstorm are quite often. I use a Si4461 RF chip, with a half wave whip antenna.

My problem is the following :

We had several big thunderstorms last week. And every time, I got several sensors dying at the exact time the thunderstorm was here.

Only the RF chip is dead. The other components looks undamaged.

It seems like to be because the antenna is picking-up static electricity from the thunderstorm.

So my question is : how to protect the RF chip from thunderstorms ?

I've been told that an « ESD suppressor » like this could do the job : http://www.mouser.fr/ProductDetail/Cooper-Bussmann/0603ESDA-MLP7/?qs=/ha2pyFadug/ksZDRDWi4cQDcjEmIJ07mgZKTEB3xPvlqKzTt8q7CA==

Someone else told me about using a choke and a TVS diode.

This device is battery powered in a plastic enclosure. Grounding will be difficult.

\$\endgroup\$
1
2
\$\begingroup\$

One method uses a choke to ground that is "high" impedance at 800 MHz or whatever RF is and low impedance at 0 to 30MHz. High , that is relative to antenna impedance.

The other method is to confirm no ground shift for lightning discharge to ground . i.e. a deep ground rod to avoid shield pickup.

The 3rd method is to use a direction loop antenna which is inherently low impedance below 30MHz, say.

The 4th is a half wave loop and a whip antenna in some combination, maybe horizontal loop and vertical whip with impedance transformed cable length for matched Z and omni-direction in horizontal plane.

To reduce the risk of direct hits requires an array of sharp tipped rods 10m above your antenna and deeper than your ground rod. There will still be inductive coupling so double shield or semi-rigid coax performs better. The same is used on power substations. But expensive and a double edge "saber" on a mountain top. It would also attract higher probability of nearer strikes.

\$\endgroup\$
0
\$\begingroup\$

If you have connectorized antenna, an easier solution would be to get a lightning protector. For example:Lightning protectors

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.