Reg Edwards wrote:
"SideBand" wrote in message
m...
Anyone out there know of any decent solution to getting 160M working in
a mobile? The application is a semi-truck. I've got the Iron Horses for
75, 40, 20, 15, and 10M, but I'd like to work something out for 160
meters that will work on the truck.
I know I'm going to take an efficiency hit, but you're doing that for
everything except 10M on a Semi anyway.. Just so I can get a signal out
there to be heard, in the off chance.
ANY suggestions or ideas would be greatly appreciated.
73 de AI8W, Chris
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For design and performance of a 160 meter band vertical antenna, download
program HELICAL3 from website below. There are other loaded vertical
programs..
Use 1.5" or 2" diameter plastic pipe, with helical winding of thick enamel
insulated wire, mounted on vehicle roof, as tall as possible, stayed, with
short, top caapacitance tuning rod.
Range on 160m with a few hundred watts = 100 miles at noon on groundwave.
1700 miles on very quiet, wiinter nights at midnight via F-layer.
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Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
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Reg, et al:
On the Vertload program, I've been playing with the numbers a bit, and
I've found some things that I have questions from the pro's on..
First, let me explain the situation:
The Truck in question is a Ford LTLA9000. I plan on mounting this
antenna 6-8 inches from the side of the tractor on a mount coming off of
one of the fuel tanks, which are mounted just below the
driver's/passenger's door.
The cab (driving area) of the truck is about 4 feet shorter than the top
of the sleeper. The cab is all steel. I use a mag mount 5/8 wave 2M
antenna on top of the cab, with great results.
The fuel tanks are aluminum. The straps mounting the fuel tanks to the
frame are steel, and mount directly to the frame of the truck under the
cab. The sides of the sleeper are steel, up to the level of the top of
the cab. The top of the sleeper is fiberglass, with steel runner
supports inside.
I plan to mount the antenna off of the fuel tank straps, which will put
it roughly 8" to a foot away from the cab, and the steel sides of the
sleeper. I have several places I can guy the coil to on the side and top
of the cab. I have one or two places I can put PVC standoffs on the cab
and sleeper to keep the antenna away from the cab, and to keep it from
"flying out" while rolling down the road.
This truck, with a trailer on it and a full load (80,000 lbs gross
weight) is capable of traveling at 117 MPH on a straightaway. Faster if
I "turn around" the transmission again (no plans on that.. I'm getting
too old for high speed "chicken truckin" anymore). I usually keep it
down to around 70MPH when the speed limits allow.
So, I've planned on using 1" copper pipe for both the mast and the
"whip" at the top, for ruggedness. Inside the coil, I can use some 1" ID
PVC for support, and put the 3" coil over those supports, with end caps,
etc...
Now, on the antenna, I've found that moving the loading coil up higher
on the whip increases the efficiency. So:
1. Does that efficiency increase come at the cost of bandwidth?
2. Does having the load closer to the base increase the bandwidth, if
all other numbers (coil diameter, coil length, etc) are the same?
3. Would getting the loading coil above the "steel" increase my chances
of making a usable antenna with the bandwidth and efficiency I desire?
I know I'm asking the impossible here; that is a wider bandwidth, higher
efficiency, shortened 160M antenna for mobile operations. Like I said,
I'd like to get about 10-15KC of usable bandwidth, with an efficiency
that'll let me get an ERP of more than a watt or two with 100 watts in.
On top of that, I'd like to build it.
Hope this wasn't too much information, and I hope you all can make sense
of this.
73 de AI8W, Chris