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Best Antenna
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stylzmovement
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Post Best Antenna Reply with quote
What antenna do you use ?
do you like your coverage?
are there any problems with the antenna ?
will you like to change the antenna to another ?
for what reason?
Sat Feb 11, 2006 3:26 pm View user's profile Send private message
Sir Nigel
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I use the Comet antenna. The only thing I would like is more gain, however considering most omnidirectional antennas do not have a whole lot of gain, I guess it's fine. I've felt the coverage for 15 watts at 70' was okay considering the signal had to clear trees that were quite tall.

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Sun Feb 12, 2006 6:01 am View user's profile Send private message Visit poster's website
stylzmovement
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sir nigel ,
what is the range you get from you comet at 70 ft and 15 watts input?
Sun Feb 12, 2006 6:44 pm View user's profile Send private message
pcs
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Post Re: Best Antenna Reply with quote
stylzmovement wrote:
What antenna do you use ?
do you like your coverage?
are there any problems with the antenna ?
will you like to change the antenna to another ?
for what reason?


From our website:
1.) The best omnidirectional single antenna right now is 3/4 wave.
2.) If you have a bit more money, 4 dipoles in multi-bay really kick ass.

If cost is an issue, comet really performs nicely and is also nicely build.

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Mon Feb 13, 2006 1:16 am View user's profile Send private message Visit poster's website
Sir Nigel
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Post Reply with quote
stylzmovement wrote:
sir nigel ,
what is the range you get from you comet at 70 ft and 15 watts input?



I've achieved strong reception of about a mile, decent reception up to three and spotty and choppy reception of around 5-7 miles.

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Mon Feb 13, 2006 2:48 am View user's profile Send private message Visit poster's website
stylzmovement
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any other user have anything to share about the antenna you use?
Thu Feb 16, 2006 2:36 am View user's profile Send private message
cliffyk
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I'm using a DIY "slim-jim" constructed pretty much in keeping with these plans from a PCS site link. I rescaled it for 104.1 MHz, it's resonant at 103.8 MHz, and I'm running 7W from a MaxPro I into it at a couple MHz less than that with a VSWR of 1.05:1. I modified the design a bit by using a cross-drilled hole at the lower end (rather than a notch) to allow for a bit of a stub-end of PVC on the inner pipe, and used nylon push-pins to secure the wire ends (18 ga. solid copper) at the gap.

It's only about 20 ft above ground (very flat ground here), fed with 50 ft. of RG-8. I'm delivering rock solid stereo reception out to 1-1/4 miles, a bit noisy but soild to 2 miles and as much as 3+ miles if the wind is right...




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Sat Feb 25, 2006 5:33 am View user's profile Send private message Visit poster's website
cliffyk
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Me again,

You may want to check out this series of articles describing modeling of j-poles and "slim-jims"--the author's conclusion is that nearly any j-pole based design will deliver 5+ dB gain at 6° above the horizon. This is 1.0 to 1.5 dB better than a 5/8 λ ground plane, and probably 2 dB better then a 1/4 λ GP.

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Sat Feb 25, 2006 5:49 am View user's profile Send private message Visit poster's website
cliffyk
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OK, one more then I'm done...

The same fellow that wrote the j-pole modeling series performed this exercise modeling 2-meter ground planes at 1/4 λ and 5/8 λ--the results are interesting and although pefromed for the 2 meter ("146 MHz") band they remain relevant at 3 meters.

The bottom line is that for high mounted antennas the 5/8 λ has very little practical advantage over the 1/4 λ model because the longer vertical element's advantage is almost entirely at the higher radiation angles.

This is all fresh in my mind because I just completed a week's research into finding a higher performance alternative to my homebrew slim-jim, which intuitively can't be the "best antenna" (I mean heck, I made it myself for less than $10)--however, it turns out it probably is the best, unless you want to setup and tune an array, or use a directional rig to beam the signal...

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Sat Feb 25, 2006 6:11 am View user's profile Send private message Visit poster's website
Dr. No
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cliffyk wrote:
OK, one more then I'm done...

[snip] at 1/4 λ and 5/8 λ--the results are interesting and although pefromed for the 2 meter ("146 MHz") band they remain relevant at 3 meters.

The bottom line is that for high mounted antennas the 5/8 λ has very little practical advantage over the 1/4 λ model because the longer vertical element's advantage is almost entirely at the higher radiation angles.
...


I find one other advantage using a slim jim over a comet. The slim jim I built can be on a thin pole set higher than a comet, from the same tower as a starting point. There is less wind resistance IMO. With solid 30 feet of 3 legged tower, one can push up almost another 30 feet of one inch steel mast tubing (about 20 feet above the tower) with a desert slim-jim on top of that. If the wind is real high, or you want to go higher still, you can use guy wires ten feet below the base of the desert slim jim. Elevation is key. In an equal height antenna test, i find the slim jim to work slightly better than a comet.
Sun Feb 11, 2007 8:42 am View user's profile Send private message
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