Mobile & different antennas
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Let me add one experience.
During this year's APE travels, I was using a Tarheel, Model 75.
When installing it on my car, at 1st I used a ball-mount that I had used in previous years, with a 102" whip, and a long random wire, alligator clipped to the small corona ball at its tip.
This year, I made an extra heavy luggage rack mount, that had the Tarheel motorized coil above the roof level.
In testing, mounting the Tarheel coil above the roof level, on the luggage rack, was 2 s-units better on receive than the ball mount on the left rear quarter panel with the same antenna.
Then, replacing the 72" standard Tarheel whip with the 108" whip, added another 2-3 S units on receive.
My deduction is that raising the Tarheel motorized coil above the roof level both enhanced my receive and transmit.
If I get the time, I have a 17' telescoping stainless steel whip that I'm going to try.
On the down side, there'll be no matriculating down the road with that beast attached.
From: Stephen Melachrinos via groups.io <melachri@...>
To: main@070Club.groups.io <main@070Club.groups.io>
Sent: Wed, Oct 20, 2021 4:32 pm
Subject: Re: [070Club] DM53
That makes sense. I guess I shouldn't have been as specific about ground planes as I was, but your details are consistent with the thought: most antenna mounts on mobile vehicles will favor some directions and dis-favor others, due to the interactions between the antenna and the body of the vehicle, and the unique placement of the antenna.
Maybe we need to suggest that Kathy find a parking lot and drive in circles and let Dick stop her when there is maximum signal strength for each QSO. Only problem is that will delay their travels. (just kidding about the suggestion)
From: Rick - N7WE <n7we1980@...>
Sent: Wed, Oct 20, 2021 5:31 pm
Subject: Re: [070Club] DM53
At the risk of speaking for Dick while he is in transit, here's a bit of info about his mount. At least this is the way it was when we had lunch a couple of years ago. The vehicle is a van and the antenna base (ham stick) is at about the midline of the van, on the driver's side rear. I think he used a FireStik SS204 mount placed under the tail light assembly with the 3/8-S0239 nub about a half inch in the clear. Given the 48" length of the lower half of the helical wound Ham Stick, about half of it is above the roofline. Of course, the whip is well clear. I think probably what impacts the pattern more than anything is the location of the antenna to the rear of the vehicle and the counterpoise from the van body being offset as opposed to centered. That would explain the signal strength based on vehicle orientation. My thoughts anyway. I was too dumb to ever figure out a mobile mounting so just went with /P during my travels - magmount Ham Stick in the center of the vehicle roof.
Rick - N7WE
070 - #1602