Re: KC3EF 4/20 After Action Report

Jerry N9AVY

My 2 cents worth ...

Not an ideal spot to mount HF antenna. Years ago I had a minivan and mounted antenna on left rear quarter panel about half ways up. It did okay mostly. Any higher and I hit overhead wires which were sometimes too low or low overpasses. Everything worked pretty well until I got new van and mounted the High Sierra HF-1500 a bit lower... some impatient person passed me on left trying to get into left turn lane. Driving a big, black muscle car (her boyfriend's) she had a nice white stripe from front to back. Sure she heard about it from BF.  The high Sierra was destroyed and before I could get replacement parts High Sierra went belly up.  (Deductible was more than parts !)

Eventually went with 3 magnet mount on roof with ham stiks which worked fine except on 40/80m (wind loading problems pulled antenna off - and mag mount).  This worked okay until I worked for a company with said "NO" to ham radio. Was SSB back in those days and enjoyed whizzing alone highway yakking with hams in Europe & Australia.

A ham stik mounted in center of van roof is what works and gives best radiation pattern, but clearance to tip has to be less than 13" 6" otherwise you'll have problems with overpasses and drive up windows. Yes, I lost a few Ham Stiks to drive up windows because I was too lazy to get out a walk !

Am sure there is info somewhere on net about mobile antenna installs, but one needs to hunt for it.

Jerry N9AVY

On Wednesday, April 21, 2021, 12:09:22 PM CDT, Steve W3HF <w3hf@...> wrote:

Thinking about this and Dick's description of his setup (hamstick on a tail light mount), I have a few questions and a speculation:

- What does the tail light mount look like? I presume it's a bracket that sticks out between the tail light lens and the metal body of the car.
- Which direction does it stick out--to the back or to the side?
- Which tail light is it on?
- How much of the hamstick extends above the top of the T&C minivan? (Or what fraction of it is below the roof line?)

I wonder if part of this could be the direction the car is pointing and thus the location/orientation of the ground plane, which is affected by the answers to the questions above. It might be an interesting experiment some time to find a large empty parking lot and ask Kathy to drive around the perimeter so that the car ends up rotating 360 degrees (multiple times). If we had multiple stations listening, all in different directions, we might be able to get an idea of the pattern the antenna-on-car generates.

And if someone is good with antenna modeling software, we could compare the experimental pattern with an analytical prediction.


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