New Truck Antenna Setup- Why are they doing it that way?

[nbsr]

Pick your flavor of truck, WS, KW, Mack, Pete, all new factory antenna systems are crappie to say the least. I’ve tested many with an AA 35, doing an SWR scan, the best I’ve come by are 2.5, the worst 50. Resonance is in the low 26 MHz range.
The standard issue is dual antennas where the stud is mounted in plastic or mounted to an ungrounded mirror bracket with reference to the rest of the vehicle. The two pieces of each antenna coax are not a quarter wavelength, terminated in male Motorola connectors, sometimes rg 59, sometimes 58, sometimes connected to a multiplexor.

The fix is simple, some are a more pain in the ass, but simple, nonetheless. A single grounded antenna angled forward slightly (if necessary to get away from those 10 by 114 stacks, 5 airhorns, 14” reverse bowtie) and new 50 ohm coax. Not backing any antenna producers here, but minimum 3’ or coil above the roof line, and the range of SWR is 1.3 to 1.8 with resonance closer to 27 MHz.

My question is: Are they attempting to use the coax feed as a counterpoise similar to no ground antenna systems (if they are, even that is being done incorrectly)? What am I missing to understand their approach?

 

[secret squirrel]

I think it just comes down to accountants, not engineers in just about everything today. Whatever they can do cheapest just to say its included. Take for example we have no shortage of buttholes in the world yet TP is smaller rolls than 5 years ago.

 

[9C1Driver]

Plus the cb and stereo antenna is combined I believe,that’s why for a dedicated cb antenna you just run a new one.

 

[fourstringburn]

Probably won't be long that trucks won't have factory antennas and coax installed. Older trucks didn't have them. I can go for days and not hear drivers using radio's, those CB trucking days are about over.

Only when encountering major traffic jams from accidents or construction zones do the radio's light up, but rarely are drivers going the opposite way give a heads up because it doesn't affect them. So why bother?

Yes, the factory antennas and coax are usually junk anyway and most drivers who do run radio's will most likely change them out.

Coax doesn't have to be a 1/4 wavelength long, that's CB shop myth still perpetrated to this day. Your antenna should be a 1/4 wavelength either physically or electrically.

If the brackets aren't mounted to a good metal source, then a ground strap should be used for a better DC ground.

I don't think any thought is given by the truck manufactures about radio theory, it's just there for convenience. Using a coax as a counterpoise from lack of ground would be way beyond any consideration I believe, and it's a dumb idea at that.

Coax is usually cut to fit and appears to be installed when all the electrical wire is in being done before the truck interior is installed. That's why on some trucks it's hard to rip out the factory coax and the CB/AM-FM diplex box being it's usually zip tied down and tucked away.

 

[unit_399]

Probably won't be long that trucks won't have factory antennas and coax installed. Older trucks didn't have them. I can go for days and not hear drivers using radio's, those CB trucking days are about over.

Only when encountering major traffic jams from accidents or construction zones do the radio's light up, but rarely are drivers going the opposite way give a heads up because it doesn't affect them. So why bother?

Yes, the factory antennas and coax are usually junk anyway and most drivers who do run radio's will most likely change them out.

Coax doesn't have to be a 1/4 wavelength long, that's CB shop myth still perpetrated to this day. Your antenna should be a 1/4 wavelength either physically or electrically.

If the brackets aren't mounted to a good metal source, then a ground strap should be used for a better DC ground.

I don't think any thought is given by the truck manufactures about radio theory, it's just there for convenience. Using a coax as a counterpoise from lack of ground would be way beyond any consideration I believe, and it's a dumb idea at that.

Coax is usually cut to fit and appears to be installed when all the electrical wire is in being done before the truck interior is installed. That's why on some trucks it's hard to rip out the factory coax and the CB/AM-FM diplex box being it's usually zip tied down and tucked away.

GREAT POST !!! Agree 110%.
- 399