102 whip antenna on 97' freightliner

If more of the antenna is going to be obscured by the cab, then I am going to say no.

For a 102 to work properly, it has to be either above on the roof or most of the antenna can't be obscured by something. i.e. if the antenna sat behind the cab and sandwiched between the trailer and only 3 feet stood up in the air, you'd have some real high SWR issues going on.

 

The 102" whip is a great antenna; however, it radiates outward along the entire length of the antenna not just at the top. When you are mounting it behind the cab and in front of the trailer, the cab and trailer will block most of the antenna length and screw up the ability to get the signal out. If you are driving flatbed, maybe but most likely not a great idea. If you are driving a van, a better solution would be a 4, 4 1/2 or 5 foot antenna.
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If you are planning on a one antenna set up, you do know that you run 50 ohm RG-58, RG-8 etc but not 70 ohm RG-59 coaxial cable. Right?

 

Hey Xcis, are you to say that it might be better to run 2 short antennas instead of one massive antenna?

 

Agreed, it would serve no purpose to hide the majority of the antenna between the truck and the trailer.

 

If you mount it on the bottom step, it will be ok. Most drivers that do this will have a bunge strap around the antenna at the top of the hand hold to keep it from flopping so much.

 

Since I am not advertising for a currently "in business" company, I guess it is ok to mention that I have built over 18,000 antennas under the now defunct corp. Antennas By MasterCraft. The antennas were the Viper Mach I and II.

The Vipers that you NOW see on the market are sonewhat copies of my antennas that do not work as well.

If you could see the graph of a 102" whip that shows the output power from top to bottom, you would find that at the very tip, there is NO output except straight UP, which of course, is of almost no use.

The power from that point to appx halfway down the shaft is at a 37 degree angle which of course means that the antenna from the tip to the center puts out more and more and when it gets to the center of the antenna, the power output stays in parallel with the rest of the shaft to the bottom.

Whenever you have the top of the antenna low enough to NOT hit bnridges etc. most of the power is being radiated into the cab of your tractor.

A single large coil antenna mounted on the drivers side mirror with the coil bottom level or above the roof line.

Billy Dean Ward

 

The SWR [standing wave ratio] reading measures how much of the radio wave being transmitted is reflected back to the radio. To much being reflected can damage the power transistors that are also called "the finals". Large swr readings, 3.0 and higher, can be caused by bad antenna grounding, broken coax and broken wire inside the antenna. This I understand.
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Here is what I am unsure about. If the radio wave is transmitted by the antenna but blocked by the tractor, trailer or some other object; will the radio wave get back to the radio and cause a higher swr reading?
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To reply to a previous poster, I avoid tiny antennas that are less than 4 feet long. While I have never used a 2 or 3 foot antenna, I have serious doubts that they would be at all effective. My personal preference is for an antenna in the 4 1/2 to 6 foot length. The more antenna length that is out in the open and not obstructed by the cab the better. That is just me.
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If the co-phased antenna setup in the truck was in working condition, I would run 2 antennas. A 2 antenna setup would provide a better signal distribute pattern when some of the signal is bocked by the trailer.
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If I had to replace the coax, I would use RG-58 or RG-8 and do a one antenna setup. The signal pattern around the tractor and trailer would not be the greatest. To some that is not acceptable but I can live with that. Call me lazy if you like but I just hate to route coax through holes in the company truck. I had to run cable once on a non trucking job and I swore never again. Man, I truly hate to route cable.
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HINT: If you just have to run cable through the truck, you can use a flexible speedometer cable to route your coaxial cable through the path.

 

I have a 102 whip. I have found that if the antenna is beside the cab of the truck it will cause high swr. I put a rubber gas line on my antenna from the bottom to just above the cab and that did get my swr down. It is very important that the antenna mount is grounded to the frame of the truck.