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eHam Forums => Station Building => Topic started by: KD2FAH on February 26, 2002, 05:01:07 PM



Title: Grounding 1/2-wave dipole?
Post by: KD2FAH on February 26, 2002, 05:01:07 PM
I constructed a 1/2-wave antenna cut to the operating frequency and it works fine. Nothing special in the construction pretty much textbook. The one thing I haven't come across is grounding.  I have my antenna strung up on my roof, its approximately 20' off the ground. No power lines or other antennas in the immediate vicinity. The thought of lightening has crossed my mind. I have not read anything recommending a ground or a lightening rod for a dipole, but I was wondering if anyone had any thoughts on this matter.


Title: Grounding 1/2-wave dipole?
Post by: WB2WIK on February 26, 2002, 06:18:07 PM
The way to lightning protect a coax-fed dipole is by installing a lightning arrestor/protector in the coaxial feedline, FAR FROM THE HOUSE, and directly ground that.  You can't ground the dipole elements themselves.  Any lightning ground should be installed and grounded as far away from your home as possible.  And again, the way to install such a ground is via a lightning arrestor installed in the coaxial feedline.

Many such arrestors are available, from Alpha Delta, Polyphaser, et al.

WB2WIK/6


Title: Grounding 1/2-wave dipole?
Post by: KD2FAH on February 26, 2002, 06:38:26 PM
Yes, I figured if lightening was going to strike it would make its way right down the coax. I will look into an arrestor for the feedline. Also, in this current configuration would you think a lightening rod on house would suffice if I didn't use an arrestor?


Title: Grounding 1/2-wave dipole?
Post by: WB2WIK on February 27, 2002, 02:46:51 PM
Nah.  It's two very different things.

A "direct strike," which of course is unlikely, will vaporize everything in its path, anyway.  So, what you're trying to do with the lightning arrestor is provide a path to ground for induced surges which are far more likely to actually occur.  Those can be very high potential (thousands, or tens of thousands of volts), but with nowhere near the energy of a direct strike -- but still capable of damaging your ham gear.  That's why it's a good idea to use them.

WB2WIK/6


Title: Grounding 1/2-wave dipole?
Post by: KD2FAH on February 27, 2002, 03:22:36 PM
OK. Got it. Will look for an arrestor for feedline and then ground arrestor. Thanks!


Title: Grounding 1/2-wave dipole?
Post by: NONE1K2 on March 02, 2004, 01:25:13 AM
I have a attic antenna.  It is 1/2 Wave for the 10 and 11 meter bands.  Its mounted in the center of my attic and I need to know how I would go about grounding an attic antenna from Step 1.  I dont know that much about antennas and ham radios, but Im getting into it.  Will someone help me please.

Eric