How to reduce/mitigate the risk of lightning at the GPS outdoor antenna ?

[Ian.M]

Its only the 1pps signal that's critical.   If you use a cheap transmitter and DC coupled receiver pair, + polymer fibre optic cable, you can probably roll your own isolated link  for about $30.  You don't have to run fibre all the way - once youv'e gone far enough that the risk of a side flash from the lightning protection conductor is minimal, you can transition back to copper.   The NMEA0183 can be handled using an off-the-shelf RF datalink as its latency is far less critical.

However powering it, short of a dedicated solar panel and battery is more problematic . . . .

[GreyWoolfe]

Here in Florida, the lightning capital of the US, lightning is a constant worry.  I don't use Polyphasers, ground rods or anything fancy.  If I am not playing radio, the 80 meter full wave loop and commercial 2 meter vertical antennas are disconnected.  Period.  I had a lightning strike hit the street in front of the house a number of years ago.  A 5/8 wave 2 meter antenna on the roof of the house, was partially gone, the loading coil inside was vaporized and 75 ft of coax was toasted.  The dielectric at the connector in the house was black.  No radio was harmed.  All the damage happened to the cable box, cable modem, the router connected to it and a couple of computers connected to the router.  I personally would be nervous having any antenna permanently connected.  Bravo, glad lightning isn't as big a concern for you.  My 2 cents, whatever you do, add the polyphaser.  In another galaxy far, far away and long ago, I used something like this for my CB radio connected to the cold water copper pipe.

[BravoV]

Its only the 1pps signal that's critical.   If you use a cheap transmitter and DC coupled receiver pair, + polymer fibre optic cable, you can probably roll your own isolated link  for about $30.  You don't have to run fibre all the way - once youv'e gone far enough that the risk of a side flash from the lightning protection conductor is minimal, you can transition back to copper.   The NMEA0183 can be handled using an off-the-shelf RF datalink as its latency is far less critical.

However powering it, short of a dedicated solar panel and battery is more problematic . . . .

Sorry, as I'm a noob on GPSDO thingies as its my 1st, just realized that I need the 10 MHz signal which is the main reason why all this troubles, I guess isolating this it self can't be cheap ? CMMIIW 

[Ian.M]

No, fibre isolating  10MHz wont be easy to roll your own for.  However many GPSDOs use the 10KHz  output available from some receivers and fibre isolating 10KHz is probably even easier than 1pps as with a constant AC signal present, the fibre receiver can be AC coupled and have AGC.

[jmelson]

If it is like the picture, the building mostly protects it.  But, if the building takes a direct lightning hit, then anything can happen.  You can have MAJOR sparks flashing across from the electrical wiring to the plumbing, set the wood on fire, etc.  If the building or the power poles outside get a direct hit, very likely everything in the building, often including the wiring in the walls, will be fried.

So, what you CAN do is protect against NEARBY strikes.  One thing that causes a lot of damage is induced currents/voltages produced in wiring loops.  So, for instance, you have the electrical wires to an office with a bunch of computer gear travel through the West wall.  But, you pull network cables through the ceiling.  That forms a loop, and the voltages induced there can be substantial.  Reducing the loop area will reduce the induced voltage.  But, this may not be real practical to do in existing buildings.

Jon

[BravoV]

I've read and searched lots of lightning protection literatures for antenna, still not clear how to proceed with my installation, any experienced fellows help will be appreciated.

Assuming we follow this common good practice, here is the standard lightning protection scheme and illustration from HP 58503A/B GPSDO manual, its clear here that the lightning rod and the cable to earth is separated from the GPS antenna and has it's own lightning protection and then joined (item no 11) together at the ground wire (the red square at the ground cable).




My antenna has the integrated lightning protector, as seen below photo, the big earth wire connection with the antenna N type connector at the background. Should I provide "another" separated ground wire from this connector down to earth, or I can just connect/join this directly to the lightning rod say at the roof up there ? Cause using separated cables, that will be quite an expensive installation.

[IanB]

My antenna has the integrated lightning protector, as seen below photo, the big earth wire connection with the antenna N type connector at the background. Should I provide "another" separated ground wire from this connector down to earth, or I can just connect/join this directly to the lightning rod say at the roof up there ? Cause using separated cables, that will be quite an expensive installation.

I'd say you should follow the given instructions very carefully and precisely. If you change things around and deviate from what the drawing shows without knowing what you are doing you could invalidate the whole scheme and render it useless.

(The whole idea of connecting something "directly to the lightning rod" sounds a bit scary. The goal of a lightning rod is to collect charge and direct it safely away from the thing being protected. Not to collect charge and conduct it right up to the back door of the thing being protected.)

[BravoV]

I'd say you should follow the given instructions very carefully and precisely. If you change things around and deviate from what the drawing shows without knowing what you are doing you could invalidate the whole scheme and render it useless.

Actually I don't plan to change anything at all, the GPS antenna in the HP illustration does not have the lightning protection as mine does, look again.

I've been searching for quite sometimes now on the GPS antenna that has protection on the "detail" installation, but still no luck, yes, that includes Huber+Suhner web site. 

(The whole idea of connecting something "directly to the lightning rod" sounds a bit scary. The goal of a lightning rod is to collect charge and direct it safely away from the thing being protected. Not to collect charge and conduct it right up to the back door of the thing being protected.)

Yeah, thats the instinctively thinking, to drive open higher possibilities that the lightning will strike else where "away" from the antenna.

I guess I will have to use separated ground line connected at the antenna.

Thanks for your concern.


PS : Attached datasheet of the antenna.