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Author Topic: Outdoor Antenna Grounding  (Read 3862 times)

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Scott

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Outdoor Antenna Grounding
« on: February 15, 2010, 07:46:59 PM »
I am wondering what people have done to ground thier antenna. As I understand it, a #10 wire from the antenna to the ground rod should be enough to ground an antenna on the house to prevent static buildup and "leaders" forming durring thunderstorms. I know that nothing can protect against a direct lightning hit but does this sound sufficient? The antenna will be mounted at the roof peak on a two story home and the coax fed into the first floor. I am also planning on using a coax lightning arrestor at the point just inside the house.

Wikipedia entry on lightning and "leaders" http://en.wikipedia.org/wiki/Lightning

Any thoughts??

roadblock

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Re: Outdoor Antenna Grounding
« Reply #1 on: February 16, 2010, 01:33:52 AM »
Thats sounds sufficient enough. Just remember to keep the length of the ground wire as short and direct as possible to the ground rod. Electricity likes the path of least resistance so if your coax length to the radar box is shorter you may not be discharging the static build-up as well as you should.

As far as lightning arrestors go, they are a good idea. The ones that are designed for the frequencies that radar box operates on may be a little costly.
The standard ones that work from 1Mhz to 2Ghz may have high losses on the higher frequencies. Polyphaser makes commercial grade lightning arrestors specifically for high frequencies with low loss.

http://www.polyphaser.com/products/DSXL
http://www.polyphaser.com/products/prod/coax/sx/

The polyphaser DSXL covers the high frequency of radar box but is a dc blocked lightning arrestor so if you decide to use a pre-amp at the antenna and power it with a bias-tee (power over coax) this one wont work. You will need a dc pass lightning arrestor, polyphaser makes those too.

Just to go a little off topic, what antenna and coax are you going to use?
The reason I ask is because from my experience using radar box you will have high signal loss with increased coax length. The type of antenna (Base style with high gain) may help compensate but overall you may experience higer losses.
You may want to test that set-up before you finalize it to make sure that you have increased the number of aircraft as well as the range they are received at.
Just something to look for and keep in mind.

EMA

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Re: Outdoor Antenna Grounding
« Reply #2 on: February 16, 2010, 08:56:41 AM »
When I had an external antenna I was always concerned about lightning strikes because I live on a hill. I remember discussing this with a friend who said I was worrying unnecessarily he had been in the aviation industry and had studied this and for over 40 years had antennas on his roof. Two weeks later his house was struck by lightning taking out TV, Radio's, computer and telephones.

Never say never :-)

Scott

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Re: Outdoor Antenna Grounding
« Reply #3 on: February 16, 2010, 02:36:39 PM »
Don't most preamps have built in coax lightning arrestors at the bias T?

roadblock

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Re: Outdoor Antenna Grounding
« Reply #4 on: February 17, 2010, 09:59:21 PM »
As far as I have seen the majority dont have ligthning protection. Maybe I have just been looking at the wrong ones... Lol.  But there are Bias-T's out there that do have surge/lightning protection.