If I want to minimize "RF in the shack" and lightning hazard, what some good ways to ground a transmitter and indoor antenna in a top floor room or attic with no exterior access? (say a multi-story wood-framed building with large non-opening glass windows)
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1$\begingroup$ For more info on "RF in the shack", please see Grounding a second-story shack with an outdoor antenna. $\endgroup$– Cecil - W5DXPDec 21, 2018 at 14:06
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$\begingroup$ @w5dxp Thank you, Cecil. I added a link to that article in your comment using markdown. You can see a simpler version of that anytime by clicking the "help" link to the right of the comment box. Happy Friday, and let us know if you ever need help with that. :-) $\endgroup$– Mike Waters ♦Dec 21, 2018 at 20:31
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2 Answers
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Your solution to "RF in the shack" should be proper antenna design first, and grounding second. See Using a balun with a resonant dipole (or any other antenna, really). If you take care to address common-mode currents, you won't need a ground.
Regarding lightning protection, you might just forget about it. If lightning has struck your indoor antenna, it's already struck your house. You have bigger problems. You can try to provide a path for that energy to ground, but keep in mind: it's a lot of energy, so you need a big conductor. You don't have exterior access, so that means going through the floor. If you don't mind a couple pieces of 6" copper strap running straight through the living room you might accomplish something worthwhile. Otherwise, I'd suggest insurance.
answered Jan 9, 2014 at 17:09
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2$\begingroup$ (In the US) Look at any big house or public structure build before WW1, they all have one or more lightning rods on the roof (often decorative at least for farm houses) connected to big, fat copper wires running down the exterior of the building to copper ground rods. That's lightning protection. Anything else is lightning window dressing designed to make the insurance company honor their policy. On that note, if lightning struck the antenna through the roof (possible) expect to have a tough time with insurance unless it has a lightning ground as Phil mentions. $\endgroup$– WPrechtJan 9, 2014 at 17:48
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If I want to minimize "RF in the shack" ... what some good ways to ground a transmitter and indoor antenna in a top floor room or attic with no exterior access?
Adding to what Phil Frost said (above), which I agree. Also, you can use an "artificial ground". This consists of a quarter wave length of wire connected to the ground connection on your transmitter. The artificial ground absorbs RF. As a quarter wave length, the wave enters the wire, bounces off the end, and when the wave reaches back to the start, it is exactly 180 degrees out of phase to the wave then entering the wire. The two waves cancel. So it absorbs any RF energy at the tuned frequency. Of course, it works only at the frequency/wavelength that it is built for. You could add artificial ground wires for each band that you operate.
