Ground an antenna

Means running a ground strap from the mount to the best ground possible on the truck. Also refers to having a good ground at the bracket mounting position. Usually the newer trucks are harder to find a good grounding surface to mount the bracket to.

 

Good answer, especially as it specifies "at the bracket mounting position". Too often we see "ground bonding leads" sorta wandering hither and yon across the body towards someplace that shows DC continuity to the battery's ground, which is really quite a different thing. Ideally, the surface that we commonly refer to as the ground plane (incorrectly, but we all know what we mean) immediately adjacent to the feedpoint of the antenna and spreads out like radials (the similarity of terms to base station antennas is not co-inky-dinkal), and is parallel to the ground over which we drive. Incidentally, the ground over which we drive is the *actual* ground plane, but we've taken to using the term to mean "the biggest chunk of flat metal at the height of, and connected to, the shield of the coax near the antenna mount". Well, sorta.

Speaking of which -- I was at a Harbor Pharte store yesterday and saw something that reminded me of a product that used to be sold by the Antenna Specialist Company, now part of the same PCTEL, Inc. umbrella corporation that also includes Maxrad Antennas. ASP used to sell a roll of peel-and-stick copper foil tape about 2 inches wide and 30 or so feet long. It was to be used on the underside of Fiberglas® vehicle roofs, boat cowlings, etc., to provide an RF counterpoise where none existed. The installer, once having gained access to the bare inside of the roof, would just peel & stick this stuff in the form of (typically) a 6-legged star, sorta like the EMS Star of Life (without the snake) and install the mount through the point where all the foils crossed. The kit advertised that it had enough material for around ten UHF, four VHF, or one low band (or CB) installations, or somewhere around there.

I didn't see that just now in a brief perusal of the PCTEL site, but Harbor Freight has peel & stick aluminum tape that would do the same job. I think their roll was 2 inches wide and 150 feet long, and cost around $12 on the store shelf. Mail order price is $6.99 plus whatever they charge for shipping & taxes & stuff. http://www.harborfreight.com/2-inch-x-50-yard-flame-retardant-aluminum-foil-tape-96372.html
The thickness is only 3 mils, but you're not welding with this stuff, either

Places like Georgia Copper also sell actual gummed copper, but aluminum ought to be fine.

For a company truck that prohibits drilling holes in the structure of the cab, it's possible that running an array like rays of the sun across the inside of the roof, coming together near someplace by an existing bolt penetration might suffice for helping out with a perch or other mirror mount on a plastic truck cab. If it's OK to put a hole through the roof, then wherever you can route the stuff ought to be a help, with the caveat that the more of it that you can keep perpendicular to the long axis of the antenna, or parallel to the ground, the better, and then let the ends "droop" as necessary. Considering the size of a typical truck cab's roof, it might be best to mount the antenna offset towards one side (or corner) so that the foil radials can be nearly full length and still parallel to the ground. The radiation pattern will be somewhat asymmetrical, but it would be anyway, and having a more efficient counterpoise should help reduce the ground losses, making the radio transmit AND receive more effectively.

I actually considered grabbing a couple of rolls of the aluminum tape, but without any actual projects in mind for it, decided I could pick it up next time I need it. But at least it's there.

Just a thought.

 

Well, regardless of whether the tape gets applied to the top or the bottom of the cab shell, the idea is to have it get as close to, and "point out" from, the point where the coax feedline attaches to the base of the antenna itself. In a perfect world (well, one where vehicle roofs where still fiberglass but you weren't limited as to width), you'd mount the antenna in the middle of the roof, and the tape would head outwards in several directions for a distance of about 10 feet (making for a roof that's, well, around 20 feet wide....) But since the world (and most CB installations) are fraught with compromises already, one of them is that not all of the tape radials will be the ideal "quarter wave plus 5% length". Maybe none of them will be, once faced with the wavelength involved at 11 meters (CB). But the more radials you can fit, and the longer, then the more effective counterpoise you'll be providing.

Since your aim is to have the antenna mounted on one side, my suggestion would be to have a few passes of tape spread out across the inside (or outside) of the roof, converging at a common point right at the edge of the cab closest to the mount, from which you can run a short chunk of flexible copper flashing material (with copper hardware and Caig or similar anti-oxidation material on it) to help bond it to the tape which is stuck to the roof. From that point, the tape runs would fan out like fingers in the couple of directions that will allow it to go the greatest distance.
Another way to imagine its appearance would be sorta like what I believe was the Imperial Japanese Naval battle ensign from WW II, the one with the "rising sun" logo, but in this case the "sun" would be way over next to the antenna mount, and the flag would be viewed as if it were laid upon the roof of the truck.

Sure, the radiation pattern of the antenna system will be badly asymmetrical, but presumably the ground losses will be diminished somewhat, and the radio will be seeing a load somewhat better than what would otherwise be analagous to running a two-stroke engine without a muffler for back pressure (from my limited understanding of engines). And without a metal roof, the radiation pattern is already asymmetrical; at least now, it might be asymmetrical but with longer range

So while the antenna points *up*, the tapes will run *across* the roof, to simulate a metal roof, even though it will be one that's not solid (except for the composite shell, of course).

I also just went back and looked at your OP (D'oh!) and realized what you're using for a radio. Even though the transmitter is broadbanded enough to still put out respectable power once it's unlocked and lets one get it down into CB from the published 10 meter ham band it's supposedly marketed for, it doesn't mean that the receiver is going to work as well down there. If the place who sourced it for you *only* unlocked it so it would work in the CB band but didn't have a calibrated signal generator and the skills to use it properly to optimize the receiver for you to use it on CB, you may be working with a radio that could hear with one-eighth or less signal than it currently is to produce the same sound at the speaker. I've seen more than my fair share of rigs here that have literally just had the "magic jumper" moved and nothing more done to them.

Add to that a condition that, if you're using 40 watts out when you're talking with folks who're using only 4 or 8 or 10, even if your receiver is properly aligned to be as sensitive as it should be on the CB Band, then (at least for local stuff) you're going to stop hearing people before they stop hearing you, because you're putting out more power than they are.

I'm sorry I don't have any graphics skills, or I'd find a way to put up a sketch of the metallic roof web counterpoise fix to make it easier to follow. The receiver tuning for your radio is a matter of being confident in the shop that did/does/will do your radio work -- if it's a carry-in kind of place, they should be proud to show off their bench gear and license(s). The stuff ain't cheap, and using it isn't intuitive.

As for the TX vs. RX signal mismatch: as long as everything you have is optimized to make the most of incoming signals (decent antenna system, low RX noise, well-operating receiver), then it will come down to either operating skill, TX power parity amongst operators, or just good luck, I'm afraid.

Wish I had more concrete stuff for you, but that's about all I've got for now, and my wife says my fingers are two inches shorter than when I sat down at the computer....

73