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loop antenna for semi truck?
- Thread starter Cody Dixson
- Start date
I'm trying to wrap my mind around where you would place it. A loop antenna tends to be directional, broadside to the plane of the loop.
A tractor with a fiberglass air dam on the roof might let you put it behind the dam. Would have coverage to the front and rear, and not to the sides.
I have seen magnetic loops, fed from a small loop of coax inside the main loop. And I have seen them fed from a gamma match at the bottom, with the tuning cap across a gap at the top.
Don't have first-hand experience to offer.
73
A tractor with a fiberglass air dam on the roof might let you put it behind the dam. Would have coverage to the front and rear, and not to the sides.
I have seen magnetic loops, fed from a small loop of coax inside the main loop. And I have seen them fed from a gamma match at the bottom, with the tuning cap across a gap at the top.
Don't have first-hand experience to offer.
73
after kopcicle gave me this to think about I looked up some to get an idea of what it was and I found the delta loop
I have a flattop 98 freightliner
if I made some brackets that would hangout over the mirrors and brought it back to a point at the rear of the sleeper I watched a video where a guy talks about horizontal and vertical loops and the difference is the placement of the feed point... now I'm like you nomad I dont have any experience but I even thought about a 102 steel whip mounted horizontally across the front of the metal visor and the visor acting as a reflector
but.... just like you mentioned nomadradio I figured there might be some receiving issues or super high swr.
I have a flattop 98 freightliner
if I made some brackets that would hangout over the mirrors and brought it back to a point at the rear of the sleeper I watched a video where a guy talks about horizontal and vertical loops and the difference is the placement of the feed point... now I'm like you nomad I dont have any experience but I even thought about a 102 steel whip mounted horizontally across the front of the metal visor and the visor acting as a reflector
but.... just like you mentioned nomadradio I figured there might be some receiving issues or super high swr.
Here's a pdf of an sgc coupler manual. Among other HF antenna installations, it discusses a vehicle mounted loop.
http://www.sgcworld.com/Publications/Manuals/230man.pdf
http://www.sgcworld.com/Publications/Manuals/230man.pdf
Shadetree Mechanic
Delaware Base Station 808
Lots of hams feed loops with up to 1500 watts. On a vehicle though, I probably wouldn't exceed 200-300 watts. Not only is it not a good thing to be that close to it, but it can also zap important things like your vehicle's computer.
Here's another interesting thing: the slot antenna. https://w6nbc.com/articles/20xx-dishslot.pdf
Just some food for thought.
Just some food for thought.
To use that trick on 11 meters you would need a dish over 18 feet in diameter.
The 2-meter example uses a slot about a half-wavelength long.
73
The 2-meter example uses a slot about a half-wavelength long.
73
Homer, I have done some models by Boyer, the inventor of the DDRR idea. His design was for naval use over seawater aboard ships.
I scaled the model down to 27 MHZ with the vertical section connected to Earth. I got similar, very low gain results -17 dbi...just like Boyer reported at much lower frequencies. It was reported that the Navy used several 5,000 watt transmitter in series to get successful Tx results. The primary claim for this design was superior Rx results at very long distances. It was said, this antenna could hear crickets 1000's of miles away, when the rig was over sea water. Thus they had to generate big watts to be heard on Tx.
I also tried to duplicate Uk's Antenna Technical Author, Peter Dodd's, G3LDO DDRR mobile setup at 14 MHz, but had to make mine over a traditional horizontal 16 radial ground plane instead of using a vehicle type object for ground. My model produced horizontal RF gain at 2.09 dbi @ 5* degrees, which is very good for a mobile 5" inches above the Earth. However, the vertical side showed -20 dbi gain like the DDRR original design suggested.
Besides this mobile would be difficult to tune with all the moving parts...makes the idea impracticable IMO.
Homer, if this idea had any real merit, I think somebody might have tried making one. IMO this idea for mobile CB applications is like a boyhood pipe dream, with all the fire, sparks, and smoke that gets these guys all excited.
I scaled the model down to 27 MHZ with the vertical section connected to Earth. I got similar, very low gain results -17 dbi...just like Boyer reported at much lower frequencies. It was reported that the Navy used several 5,000 watt transmitter in series to get successful Tx results. The primary claim for this design was superior Rx results at very long distances. It was said, this antenna could hear crickets 1000's of miles away, when the rig was over sea water. Thus they had to generate big watts to be heard on Tx.
I also tried to duplicate Uk's Antenna Technical Author, Peter Dodd's, G3LDO DDRR mobile setup at 14 MHz, but had to make mine over a traditional horizontal 16 radial ground plane instead of using a vehicle type object for ground. My model produced horizontal RF gain at 2.09 dbi @ 5* degrees, which is very good for a mobile 5" inches above the Earth. However, the vertical side showed -20 dbi gain like the DDRR original design suggested.
Besides this mobile would be difficult to tune with all the moving parts...makes the idea impracticable IMO.
Homer, if this idea had any real merit, I think somebody might have tried making one. IMO this idea for mobile CB applications is like a boyhood pipe dream, with all the fire, sparks, and smoke that gets these guys all excited.
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