Grounding the Antenna or Coaxial Cable? - Canadian TV, Computing and Home Theatre Forums

rpali · 2009-09-22, 11:00 PM

I'm relatively new here so please pardon me if this is a n00b question.

I've got a 4221HD mounted on my balcony and the coax comes into my apartment and connected directly to my PVR.

I was fine-tuning the antenna aiming this evening and noticed something extremely odd. The back of my hand brushed lightly against one of the bowtie elements and I felt a low voltage shock. I can grab it firmly and feel nothing, but if I touch it very lightly with the back of my hand or my arm, there's definitely voltage there.

I've been shocked by 120 volt AC and this is certainly not nearly so strong. I don't know it it's AC or not, but I never expected the active antenna elements to be energized.

What's the deal here? The antenna isn't grounded, but I wouldn't have expected this to be a problem outside a lightning strike. The coax cable is a total of three metres long and the distance between the antenna and the PVR is maybe two metres. I can't figure out what's going on here.

Any ideas? Is this a serious problem?

Jase88 · 2009-09-22, 11:32 PM

Grounding antenna equipment isn't just about preventing/limiting damage from lightning.

The metal sheath around the dialectric of coax acts as a "faraday cage"; dissapating RF and electrical energy before it interferes with the centre conductor. Static discharge and buildup (or any electrical discharge or arcing) generates noise, which will negatively impact your reception.

Antennas will build up static charge--by the wind passing through the elements.

You need to find a way to ground the antenna. It can be difficult in a condo/apartment situation, but it must be done.

rpali · 2009-09-22, 11:42 PM

What specifically has to be grounded? The antenna or the mast to which I've mounted it to? They're both metal so I'm assuming it doesn't matter.

I'm curious though. If the antenna had picked up a static charge, the difference in potential should have equalized (between me and the antenna) fairly quickly. I detected no such change as I continued to try to feel the electricity. Very strange.

Jase88 · 2009-09-23, 01:00 AM

Both the antenna mast and the coax need to grounded (refer to the grounding thread).

You discharged the static when you touched the antenna. However, it will build up quickly again.

bigbody300 · 2009-09-28, 10:48 AM

Hi guys

I just installed my exterior antenna, and i was wondering So i need to ground my ANTENNA or the COAXLE CABLE?

And how do i do it? I have been looking for the the GROUNDING THREAD but cannot find it.

Thanks.

Cyclism · 2009-09-28, 11:09 AM

http://www.digitalhome.ca/forum/showthread.php?t=62265

2009-09-22, 11:00 PM	#1
rpali Rookie Join Date: Aug 2009 Location: Ottawa, ON Posts: 21	Grounding the Antenna or Coaxial Cable? I'm relatively new here so please pardon me if this is a n00b question. I've got a 4221HD mounted on my balcony and the coax comes into my apartment and connected directly to my PVR. I was fine-tuning the antenna aiming this evening and noticed something extremely odd. The back of my hand brushed lightly against one of the bowtie elements and I felt a low voltage shock. I can grab it firmly and feel nothing, but if I touch it very lightly with the back of my hand or my arm, there's definitely voltage there. I've been shocked by 120 volt AC and this is certainly not nearly so strong. I don't know it it's AC or not, but I never expected the active antenna elements to be energized. What's the deal here? The antenna isn't grounded, but I wouldn't have expected this to be a problem outside a lightning strike. The coax cable is a total of three metres long and the distance between the antenna and the PVR is maybe two metres. I can't figure out what's going on here. Any ideas? Is this a serious problem?

2009-09-28, 10:48 AM	#5
bigbody300 Rookie Join Date: Sep 2009 Posts: 5	Grounding the New Antenna or Coaxle Cable? Hi guys I just installed my exterior antenna, and i was wondering So i need to ground my ANTENNA or the COAXLE CABLE? And how do i do it? I have been looking for the the GROUNDING THREAD but cannot find it. Thanks.

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2009-09-22, 11:32 PM	#2
Jase88 Moderator Join Date: Jan 2009 Location: Kitchener, ON Posts: 4,110	Grounding antenna equipment isn't just about preventing/limiting damage from lightning. The metal sheath around the dialectric of coax acts as a "faraday cage"; dissapating RF and electrical energy before it interferes with the centre conductor. Static discharge and buildup (or any electrical discharge or arcing) generates noise, which will negatively impact your reception. Antennas will build up static charge--by the wind passing through the elements. You need to find a way to ground the antenna. It can be difficult in a condo/apartment situation, but it must be done.

2009-09-22, 11:42 PM	#3
rpali Rookie Join Date: Aug 2009 Location: Ottawa, ON Posts: 21	What specifically has to be grounded? The antenna or the mast to which I've mounted it to? They're both metal so I'm assuming it doesn't matter. I'm curious though. If the antenna had picked up a static charge, the difference in potential should have equalized (between me and the antenna) fairly quickly. I detected no such change as I continued to try to feel the electricity. Very strange.

2009-09-23, 01:00 AM	#4
Jase88 Moderator Join Date: Jan 2009 Location: Kitchener, ON Posts: 4,110	Both the antenna mast and the coax need to grounded (refer to the grounding thread). You discharged the static when you touched the antenna. However, it will build up quickly again.

2009-09-28, 11:09 AM	#6
Cyclism Moderator Join Date: Jun 2005 Location: Vancouver - OTA, Pioneer KURO Elite Signature PRO-141FD, 27" iMac, WDTV Live. Posts: 2,780	http://www.digitalhome.ca/forum/showthread.php?t=62265