Antennas

Joined
Aug 13, 2006
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Ok I finally got down what radio I am gonna get when the time comes. Now I need to understand antennas. I have read a lot of posts on antennas, and there's been so many options and ideas, and tangents on the subject I can't keep it all straight. So if anyone has the patience to make a guide to getting a HAM antenna here, that would be great.

I heard things like Comet, Larsen, Magnetic mount, Hatch mount... holes drilled. whatever. What I would like is an antenna I can mount, or stick on my roof with a magnetic base. Preferably very flexible so I don't have to fold it down all the time because of tree branches....... A solid mount is fine too.

Goal - antenna which requires as little fiddling around with as possible, and is great for transmitting/receiving. I want the super long range, and I want clarity, and as little messing around with as possible because of trees etc. I want a SET IT AND FORGET IT antenna damn it! :D
 
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Here's an interesting piece of information from the Larsen site. I have been looking at Comet and Diamond antennas too.

Ground plane availability is another critical factor in mobile antenna performance and must be considered when
determining the location and type of the antenna. Ground plane requirements vary given the type of mobile
antenna and the frequency of operation. A typical 5/8 wave antenna at 150 MHz requires a ground plane at least
42” in diameter. At 450 MHz 15” is required, and at 800 MHz a minimum of 8” is considered sufficient.
In terms of mounting mobile antennas on a vehicle, there are five general locations: roof, front fender, rear fender,
trunk and rear window glass (although other glass mount locations may be used). Of these, the center of an
automobile roof is considered the best for mobile antenna placement, followed by the center of the trunk lid, the
fenders, then on-glass mounting. This ranking is determined by the amount of ground plane provided by the
positioning and clearance from obstruction (i.e., the roof line). The center of the roof is considered the ideal
mounting location, provided the roof is metal. The diagram below illustrates the effective loss (at 800 MHz) due to
insufficient symmetrical ground plane.
 

Cruiserdrew

On the way there
SILVER Star
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I really like the Larsen whip antennas, just remember they need to be tuned and so you need a good SWR meter to go with them.

Note also your quote is about 5/8 wave antennas, which are the best, but a 1/2 wave antenna is not as dependent on a gound plane, and so may be desirable if you don't have a metal roof-like on an FJ40.

I disagree with the quote about a glass mount, and a lip mount is a far better option. The Diamond K400 series of mounts are excellent.
 
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Thanks Ben.

For those looking to take their tests, I was told by a local HAM that the questions are changing mid summer. So if you're taking your test after mid summer, you better look for the most recent study material which should be out shortly. Otherwise go knock it out asap.
 

BenMara

Asian Redneck
Joined
Mar 10, 2008
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Hanahan, SC
Geee
oh well its been years since ive even though about takin the test
and i dont see my self talkin on ham bands legally any time soon
I forfeited my element 1, and 3 for my GROL and Radar for work
but then again i dont work in avionics anymore
 
Joined
May 15, 2002
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377
Location
Colorado
LC4L,

What are your goals? Which rig are you looking at using? 2m, 70cm, HF? How do you anticipate using it?

I have an HT (Kenwood TH-F6A) that I use in my 40 and I am installing a Comet SBB7 on my tire rack. This will be a little high, but I want to get the best tx/rx from the rig. Eventually I will put a Kenwood TM-VT710A in the 40 and my antenna rig will work well with that.

I have been discussing this on the Ham forum here:

Need antenna help - Rising Sun Member Forums

Cheers,

Jeff
 

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