[Antennas] Mobile Antennas - which shoots best, is strongest?

Thu Jun 15 23:46:51 EDT 2006

Thanks Doc,
The rooftop antenna described on the Preditor Antenna page is a 16-1/2 foot 
vertical radiator with a 15 inch top hat.
http://kj9t.150m.com/Predator_on_Roof/index.html
That's a reasonable structure for the roof. 33 or 35 feet would be much 
better, but the torque would be rather large.
I know of one fellow who has two roofs, he mounted a Sheakespere 35 foot 
heavy duty marine whip on the lower roof, and bracketed it to the side of 
the higher side wall - I guess he had about eight feet or so of vertical 
support.
That is an awfully heavy antenna - on ships they were anchored to steel 
decks with a bunch of 3/16 inch stainless bolts (perhaps bigger size).
73
David N1EA
----- Original Message ----- 
From: "Dr. William J. Schmidt, II" <bill at wjschmidt.com>
To: "David J. Ring, Jr." <n1ea at arrl.net>; <Antennas at mailman.qth.net>
Sent: Thursday, June 15, 2006 11:21 PM
Subject: Re: [Antennas] Mobile Antennas - which shoots best, is strongest?
I think there are better choices than a mobile antenna for a roof-top, but
if you want to proceed in that direction...
I own a variety of mobile antennas including a Bug-Catcher, a Predator, some
full-sized whips (for all bands 6-17 meters), a Hi-Q and a few others that I
can put on my vehicle at any time (all trailer-hitch mounts with excellent
ground connection via a welding extension lead plug/pin set). We (NAQRO)
are about to make some of our own tests with these and a few others for
publication... but I can give you some qualitative results in advance from
experience (so take it for what its worth at this point).
I've found that mobile antenna gain for transmitting is rarely a
problem...but rather gain for receive is always THE problem. The
Bug-Catcher seems to be the best all-around antenna for BOTH receive and
transmit... It will tolerate a tall whip and cap hat because of its coil
strength. It has a very large/ high-Q coil, but suffers (obviously) from
the coil TAP syndrome. The Predator is my next choice.. not quite as much
gain as the Bug, but doesn't suffer from the TAP syndrome. The coil is
large again, so the coil A is good. It has good mechanical strength, so an
extended top whip and cap hat is possible. The Hi-A is my next favorite,
but with the Predator, I rarely use it. Of course I always use the full
sized whips whenever I can,,, they are better than any loaded antenna unless
it is mechanically longer to start (and then there is still is no guarantee
in will absolutely be). All of these antennas take my full legal limit
mobile amp.
With all this said, you will find the counter poise and radial system to be
almost more important than the antenna selection. It you don't do this
right, no matter what you do...the antenna will never work right.
Sincerely,
Dr. William J. Schmidt, II K9HZ
Trustee of the North American QRO - Central Division Club - K9ZC
Email: bill at wjschmidt.com
WebPage: www.wjschmidt.com
"If you drink... don't drive. Don't even putt" - Dean Martin.
----- Original Message ----- 
From: "David J. Ring, Jr." <n1ea at arrl.net>
To: <Antennas at mailman.qth.net>
Sent: Thursday, June 15, 2006 11:49 AM
Subject: [Antennas] Mobile Antennas - which shoots best, is strongest?
> I've been looking at some of the beautiful mobile antennas for sale, in
> the
> Hi-Q, Predator, and GS antennas.
>> The Predator is shown here:
> http://kj9t.150m.com/N9JMXs_Predator_1/index.html
>> The Hi-Q is shown here: http://www.hiqantennas.com/
>> The GS antennas are shown here: http://www.gs-mfg.com/pages/antdiv.html
>> The GS according to the "Antenna Shoot Out" results shown on their web
> page,
> seems to perform best, and there is one report that it is made better than
> the Predator, however the Predator will take full legal limit.
>> I was thinking of using one of these mobile antennas and extending the
> whip
> and using a capacitive hat and installing it on my roof and using for 80
> meters and above. If I can get the length around 22 feet, and/or use a
> bigger top hat, I might consider 160 meters!
>> Could anyone offer any guidance, or point me to any web sites that might
> have some actual "shoot out" ratings?
>> Thanks in advance for your help!
>> 73
>> David J. Ring, Jr., N1EA
> =30=
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