GNSS antenna: importance of lightning protection - Page 1
Forum section: electronics / beginners

author: matthuszagh
author_rank: Frequent Contributor
timestamp: January 08, 2025, 12:54:07 am
content: I'm planning to use the cinder block procedure from here (https://learn.sparkfun.com/tutorials/how-to-build-a-diy-gnss-reference-station/all#introduction) (and picture attached) to place 2 GNSS antennas on my roof. One antenna is a pinwheel that is fairly small and looks not too different from the attached image. The other is a larger choke ring antenna (38 cm in diameter). How critical is it that these are properly grounded for lightning protection? I was planning to follow a procedure from (https://www.groundedreason.com/how-to-ground-an-outdoor-antenna/), but with surge arresters for the coax grounding block (ground still obviously clamped to house grounding rod). However, this is a bit of a pain and will require much longer coax runs than if I simply run the coax direct from the antenna into my lab. That will require a much bigger expense in terms of additional coax, connectors, cold shrink tubing to protect the connectors, etc. How bad an idea is it to omit the lightning protection? If it's important, I'll do it. But, these aren't large metallic antennas. They're fairly low profile on the roof. I don't get much lightning here (Oakland CA), but it happens occasionally.

author: m k
author_rank: Super Contributor
timestamp: January 13, 2025, 10:07:15 am
content: With lightning rod you're doing two things.First you're grounding some stuff and second you're creating a possible tall and grounded peak.

author: TX5Z
author_rank: Newbie
timestamp: January 13, 2025, 04:12:39 pm
content: Good question, I'm following this...Ithinkthe bonding of your antenna is not for direct strikes, but for nearby strikes. (A direct strike will fry regardless.)

author: tautech
author_rank: Super Contributor
timestamp: January 15, 2025, 03:34:28 am
content: I would strongly advise against using mains PE for lightning grounding.Instead it should be a standalone and a dedicated lightning strike protection system.We have these on off-grid data systems along with a system ground, consisting of lighter cabling to a single 2m earth rod.The lightning protection system is much more robust and entirely separate of the system earth.2x 2m earth pegs, 2m apart and 2m from system ground.Lightning rod is 2m of copper coated steel extending 1.5m min above any part of the system.All joints use heavy crimped lug connectors to heavy Galv or stainless fixtures wired with 16mm2cable.....

author: TomWinTejas
author_rank: Regular Contributor
timestamp: January 16, 2025, 04:06:51 am
content: Quote from: tautech on January 15, 2025, 03:34:28 amRefer to your local code. Here in the US the NEC requires antennas, masts, and coax shield to be bonded to the same ground rod(s) that the electrical panel shares. You may drive in one or more rods closer to the antenna, but you'd still have to tie those in to the existing rods with the appropriate sized conductor.

author: m k
author_rank: Super Contributor
timestamp: January 16, 2025, 06:27:55 pm
content: Using and bonding are different things.Where is the ground point?