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Author Topic: Two meter- 1/4, 1/2, 5/8 wave  (Read 3182 times)
JASONK
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Posts: 6




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« on: January 06, 2002, 12:08:28 PM »

I'm getting my tech license later this month. For now, I have a two meter mobile in the mail, and I was wondering what antenna works best for a mobile setup-the 1/4 wave, a half wave or a 5/8 wave. Mounting will not be a problem, as my vehicles are all old. I'm leaning towards a 1/4 wave whip, as they're easy to build and the local repeater is only three blocks south of my house. Will a 1/2 wave or a 5/8 wave substantially outperform a 1/4 wave whip? Thanks,

JasonK
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KC8AXJ
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Posts: 303




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« Reply #1 on: January 06, 2002, 04:46:28 PM »

Congrats on becoming a Amateur operator and welcome !!

It my cost a little more but for BEST overall performance get a 5/8-wave antenna. I have Larsons. Excellent quality!
Basically, a 5/8-wave antenna will radiate your R.F. signal at a lower angle than a ¼ wave. As 2M is a  “line of sight” frequency, any radiation going up at a high angle is lost  out into space. You want to keep your signal down as close to the horizon as possible for longer range.
You’re off to a good start by asking around for opinions before pulling out your wallet. You can spend a lot of money with this hobby as it is, and you don’t want to regret anything you do.

73 and HAVE FUN with your new hobby!
Steve  
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KG4PJI
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Posts: 15




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« Reply #2 on: January 08, 2002, 10:46:06 PM »

I second the 5/8 wave antenna. I too have a Larsen 5/8 wave on my truck for two meter mobile. Grounding is important in all antennas but more so for the 5/8 than the 1/4. The other thing to think about is where you take your vehicle and how you use it. The 1/4 wave will be about 14 in. or so and the 5/8 wave will be about 49 in. Either way you will do fine in and around town on about 10 watts either way.
Good luck to you on your tech. exam. If you study you will surely pass and welcome to ham radio.
73, KG4PJI
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JASONK
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Posts: 6




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« Reply #3 on: January 09, 2002, 01:24:56 AM »

Thanks for the replies, guys. Looks to me like the 5/8 antenna is the way to go. Overall height will not be a problem.

Jason Kendrick
(with only eleven days until test time!)
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KC8AXJ
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Posts: 303




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« Reply #4 on: January 10, 2002, 07:57:08 PM »

Jason,
Good luck on the test.
Are you aware about Internet sites were you could take random tests from the actual pool questions? I could send you the links just let me know.
73
Steve kc8axj@arrl.net
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JASONK
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Posts: 6




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« Reply #5 on: January 10, 2002, 09:24:50 PM »

Steve, Using this site's test page, I'm currently scoring between 85% and 96%. I've reviewed the entire question pool once, and I plan on doing it again at least once more before I test the 20th.

Jason Kendrick
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KC5JK
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Posts: 98


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« Reply #6 on: January 22, 2002, 05:33:04 PM »

   As you can see, most hams like the 5/8 best.  I prefer the 1/2-wave, and have used it for about thirty years.  The VP of a major ham retail outlet (stores in several states) asked me what I was running once, because I was the ONLY mobile he could consistently copy on 2-meter simplex (direct) over a distance of about 65-miles.  It is the old tried and proven Antenna Specialists ASPS-177, which even Motorola installed on vehicles for the demanding commercial FM mobile service.
   Of course, I also use Larsens on several bands, and you will always be perfectly happy with them too.  Either is a worthwhile improvement over a 1/4-wave, unless you are already full quieting or solid copy.
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KE4SKY
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« Reply #7 on: January 28, 2002, 02:29:31 PM »

The 5/8 wave mobile antenna will work best if you are in flat, open country and need the most range to reach repeaters or other stations on simplex which are at or slightly over your radio horizon.

A 1/4 wave antenna has a "fatter" radiation pattern and a high radiation angle which is much better for getting up, out and around terrain and obstructions. If you have to operate mobile while driving down a valley surrounded by high terrain in Colorado or even West Virginia or Pennsylvania, where most repeaters are up high on a mountain somewhere, a high gain antenna with a flat, narrow radiation pattern down on the horizon is NOT what you want.  Ditto if you are down or out on the water and the repeater is on a high broadcast tower ashore miles away.  With a 5/8 wave you may be stuck in an RF "hole."

A quarter wave antenna when used with a ground plane is unity gain and low profile which works well in most indoor garage situations.  Its wider pattern and higher radiation angle give you better multipath probabilities which may make a difference between "getting out" or not.

For instance, my hunting cabin in Berkeley County, WV in FM09 is at 600 ft. AMSL and on on a "bench" a mile behind and below the crest of North Mountain, which is 1083 ft. elevation near my location.  My home repeater is a single-site machine in Tyson's Corner, VA, FM18, about 70 air miles away.  When using a high-gain stick or even a beam I cannot stay reliably in the repeater, because the radiation pattern can't get over the terrain, but a simple unity gain antenna on the cabin roof does!  

A half-wave antenna does not require a ground plane and is provide the same unity gain on a fiberglass truck cap, or auto window glass mount that a quarter wave does with a ground plane.  You can use a ground plane with a 1/2 wave and get about 2 dB gain.

For most single-band 2-meter users I think a 1/2 wave is the best choice for all-around use.  Many "dual-band" mobile antennas are 1/2 wave on 2 meters and two 5/8 stacked colinear elements on UHF, which is also a great compromise.

Your mileage may vary, but those are my two cents.  
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