Good Cb Antenna Ground

[jhooten]

Wilson 4' Silver Top Load CB Antenna FGT Series

• 4' Silver Load FGT Series Antenna
• Tunable Tips Allows For Fine Tuning SWR & Resonant Frequency
• 3/8" Diameter Fiberglass Rod Construction
• Standard 3/8" x 24 Chromed Brass Ferrule
• Fully Linear Top Loaded Maximum Transfer Of Power
• 18-Gauge Silver Plated Copper Wire To Provide Higher Efficiency
• Unique Ground Lead To Help Insure Reduced Static Ignition Interference
• Static Reducing Weather Cap
• Black PVC Protective Weather Covering
• Quality American Made Product

Wilson 4' Silver Top Load CB Antenna FGT Series

Raney's Truck Parts carries all the semi-truck parts and chrome accessories you could need to have any 18-wheeler, RV, or pickup looking better than brand new!

www.raneystruckparts.com

• Wilson Flex Silver Load Series Whips
• Flexible fiberglass whip with “tunable tip” that allows for fine tuning SWR and
  resonant frequency.
• 200 Watt antenna whip
• 1/4″ Diameter tapered fiberglass construction
• Chromed brass ferrule & standard 3/8″ x 24 threads
• Design incorporates 22 gauge “silver plated” wire to provide higher efficiency
• The “tunable tip” allows for fine tuing SWR resonant frequency
• Unique ground lead to help insure reduced static and ignition interference
• Static reducing weather cap
• Clamshell

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[krokus]

One thing I question: The pics of the mount look like there is corrosion on the hardware that mounts the bracket to the bed. Is that metal all clean? Do you have zero Ohms,between the bracket and the truck bed?

 

[Tablesaw]

Depending on the type of coil they use, it may be required. Looking on line, I can find any information that says if this is a simple loaded 1/4 wave, or if it's a 1/2 wave or 5/8 wave.
Photos I find show that lead grounded to the mount.

Don’t throw rocks at me- what’s the best way to understand 1/4, 1/2, of 5/8? I’m about to start looking.

 

[krokus]

Don’t throw rocks at me- what’s the best way to understand 1/4, 1/2, of 5/8? I’m about to start looking.

Those reference the wavelength of the radio carrier. Two meter band means that the length of a single cycle of the RF is two meters long. (Wave height would be the height reached by that same single cycle.) The higher the frequency, the shorter the wavelength, due to the faster oscillation. (Same for wave height.)

So a halfwave antenna for 2m, would be roughly 1m, with some adjustment for physical characteristics of the materials.

 

[mmckenna]

Don’t throw rocks at me- what’s the best way to understand 1/4, 1/2, of 5/8? I’m about to start looking.

Right, as he said above, size of the antenna in relation to the wavelength of it's intended frequency.

A 102" whip with a spring at the base is 1/4 wavelength long on CB frequencies.

Half wave antennas do not -require- a ground plane under them (but they work much better with one)

5/8th's wave antennas have more gain than the other two, but are really long and usually only used in base installs.

For most CB antennas, you'll find base loaded 1/4 wave antennas.

 

[Tablesaw]

Awesome! Thanks again.

 

[redbeard]

As an alternative view, i'd expect that setup to never work right and the initial 'good' SWR reading was incorrect somehow. Perhaps the reading was from the radio to the amp and not amp to antenna. Those are too close to the rear of the cab and reflection will raise SWR.

 

[FiveFilter]

Yeah, but it's not just the excellent SWR he got with that 2-foot antenna. There was this as well:

"...I text a buddy of mine and had him get on his radio that lives 14 miles away from me. These little antennas are only suppose to get 1-3 miles. But I got 14.5 miles of range with a great tune...."

That would be outstanding performance with a quarter-wave whip. The planets must have been lined up just right for that initial setup.

 

[FKimble]

He mentioned that he swapped out the coax, thinking it might have somehow gone bad. A close look at that new coax and it's connections would be in order. Another place for that ohm meter to come in handy.

I am also wondering it that thick spray on bed liner is affecting the ground plane ( I am not an RF engineer ).

Frank

 

[WB9YBM]

Those reference the wavelength of the radio carrier. Two meter band means that the length of a single cycle of the RF is two meters long. (Wave height would be the height reached by that same single cycle.) The higher the frequency, the shorter the wavelength, due to the faster oscillation. (Same for wave height.)

So a halfwave antenna for 2m, would be roughly 1m, with some adjustment for physical characteristics of the materials.

in addition, the antenna type also effects gain (radiated signal perpendicular to the antenna). For example a 1/2 wave radiates more signal towards the horizon (when vertically mounted) than a 1/4 wave but then again the 1/2 wave radiates less signal upwards (at, let's say, a 30 or 45 degree angle) than the quarter wave. Imagine the radiation pattern of a 1/4 wave is almost circular (to keep it easier to understand); when going to a 1/2 wave a little bit of the signal radiating upwards is sliced off and added to the side-ways radiation.

the higher you go in antenna type (like 1/2 wave to a 5/8 wave), the more of the signals radiating upwards gets sliced off and added to the sides.

That makes 1/4 wave antennas good in the city (or in valleys) because the signal radiating upwards will reach repeaters on the skyscraper you're driving by, while a 5/8 wave will reach the next city when you're driving long-haul in the country.

 

[prcguy]

If you take a fiberglass rod of say 4ft tall or even 7ft tall and wind a 1/4 on one then 1/2 wave on another then 5/8 wave on another and range test them side by side you will probably not notice any difference between them. 4ft of capture area or 7ft or whatever is all you have and there is no magic on making it work better with different fractions of a wavelength of wire.

For a full size antenna like a 9ft 1/4 wave, 18ft 1/2 wave or 23ft for a 5/8 wave there is a noticeable difference.

I doubt if the bedliner is affecting the ground plane but I've never tested that. I suspect the bedliner has a lot of carbon black in it and its possible at some frequencies it may be absorptive to RF, but its probably at a much higher frequency.

in addition, the antenna type also effects gain (radiated signal perpendicular to the antenna). For example a 1/2 wave radiates more signal towards the horizon (when vertically mounted) than a 1/4 wave but then again the 1/2 wave radiates less signal upwards (at, let's say, a 30 or 45 degree angle) than the quarter wave. Imagine the radiation pattern of a 1/4 wave is almost circular (to keep it easier to understand); when going to a 1/2 wave a little bit of the signal radiating upwards is sliced off and added to the side-ways radiation.

the higher you go in antenna type (like 1/2 wave to a 5/8 wave), the more of the signals radiating upwards gets sliced off and added to the sides.

That makes 1/4 wave antennas good in the city (or in valleys) because the signal radiating upwards will reach repeaters on the skyscraper you're driving by, while a 5/8 wave will reach the next city when you're driving long-haul in the country.

 

[WB9YBM]

For a full size antenna like a 9ft 1/4 wave, 18ft 1/2 wave or 23ft for a 5/8 wave there is a noticeable difference.

Absolutely. Anything else would be a compromise at best (which is why the other "stuff" does not work so well).

 

[jonwienke]

DC ground and RF ground are totally different. Regardless of the existence of a DC ground, the antenna mount requires a ground plane--a 1/4-wave radius of flat metal or at least 4 1/4-wave horizontal radials. A standard vehicle isn't big enough to do a real ground plane for 11 meters, so you want to make it as big as possible. Center of the roof is the best. Anywhere else is going to negatively impact tuning and antenna performance.

If your ground plane isn't big enough, the coax shield will become a ground radial, and you'll have a weird asymmetric radiation pattern. If the coax happens to be the right length, you can get a nice low SWR, but your signal may mostly go up vertical or in the direction of the coax run instead of omnidirectional and mostly toward the horizon. The initial 14-mile contact probably happened to be in a directional lobe, and rerouting the coax made the lobe and the good tuning disappear.

 

[3King]

This is the point where a multimeter and the skills to use/read it will help out. Something has changed. Might be damaged cable, might be a failed connector, might be an improperly assembled antenna base. You need to troubleshoot your system and find the fault.

I final got around to moving my antenna from bed to the front driver side of my truck. I bought a new 3ft Wilson tuneable antenna, I also bought a bracket specific for the fit between my hood and fender. I lightly grind’d paint off the top of the fender chassis down to clean metal and bolted the bracket to the chassis. Connected the antenna and got a great ground. Ran my SWR, Had 2.5 and 1.1 SWR right away. I went to do a slight adjustment on the antenna, And went to check my SWR again. And what do you know, SWR back above freaking 3.0 on 40 & 1. Absolutely freaking annoying. I ran my
Meter, Everything showed green light hook it up tune and enjoy. I don’t understand this crap haha. 🤦‍♂️

 

[mmckenna]

To have it jump that much makes me think there's an intermittent issue somewhere.

I'd carefully check your coaxial connectors. with the antenna removed, and the cable disconnected from the CB/meter/everything else, check for continuity from end to end on the center conductor and from end to end on the outer shield.
Then make sure there is not a short circuit between the center pin and the outer shield.

Wiggle the connectors when you check it. Make sure it's not getting pinched in the hood. Also make sure the antenna to coax part of the mount is assembled correctly. There is often an insulating washer that has to be installed correctly.

 

[Ravenkeeper]

I final got around to moving my antenna from bed to the front driver side of my truck. I bought a new 3ft Wilson tuneable antenna, I also bought a bracket specific for the fit between my hood and fender. I lightly grind’d paint off the top of the fender chassis down to clean metal and bolted the bracket to the chassis. Connected the antenna and got a great ground. Ran my SWR, Had 2.5 and 1.1 SWR right away. I went to do a slight adjustment on the antenna, And went to check my SWR again. And what do you know, SWR back above freaking 3.0 on 40 & 1. Absolutely freaking annoying. I ran my
Meter, Everything showed green light hook it up tune and enjoy. I don’t understand this crap haha. 🤦‍♂️

To have it jump that much makes me think there's an intermittent issue somewhere.

I'd carefully check your coaxial connectors. with the antenna removed, and the cable disconnected from the CB/meter/everything else, check for continuity from end to end on the center conductor and from end to end on the outer shield.
Then make sure there is not a short circuit between the center pin and the outer shield.

Wiggle the connectors when you check it. Make sure it's not getting pinched in the hood. Also make sure the antenna to coax part of the mount is assembled correctly. There is often an insulating washer that has to be installed correctly.

@3King ,
Also, double check the grounding on your antenna mount bracket; if it doesn't have a good ground to the vehicle, it can raise your SWR. Other than that, I agree with @mmckenna , your insulating washer is probably in the wrong spot.