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I'm setting up an 50W Base Station, mounding antenna 15 to 20 feet on roof top. Are there large Base-Station antennas that can be roof mounted and what are the largest types for maximum transmission/reception?

 

Thanks all!

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Posted

You would likely have to look into commercial UHF antennas, but I remember a local that had a 25' tall antenna mounted to his chimney for GMRS. He had some fair range off of it to but I cannot remember what brand it was or anything else about it.

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Posted

455 super stationmaster

https://dcf54aygx3v5e.cloudfront.net/fac7232f-1b5f-434c-ba49-99be850a5a91/224caefc-f327-4032-994a-198cbba365e5.pdf

1151 super stationmaster

https://dcf54aygx3v5e.cloudfront.net/fac7232f-1b5f-434c-ba49-99be850a5a91/ff41de9d-b374-4bc3-b993-2608fb4a4548.pdf

Comm scope DB420

https://www.commscope.com/product-type/antennas/base-station-antennas-equipment/base-station-antennas/itemdb420-b/

these are large (heavy) very high gain antennas. I strongly recommend professional installation.

the 404 or 408 as recommended above should be more than adequate.

in the "smaller" super stationmaster option would be the 1150

https://dcf54aygx3v5e.cloudfront.net/fac7232f-1b5f-434c-ba49-99be850a5a91/77717898-351e-4ca2-a80f-4dfb99e58e7c.pdf

given your proximity to Philly and Trenton my recommendation is to get a 5-6 dB lightweight antenna on a 10' mast and you should be good to go.

 

JE

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Posted

The LARGEST UHF Base antenna available without special order are 16-bay dipoles.  On special order you can get a 32-bay dipole.  The real question is how much wind load your roof mount can handle and how much you are willing to spend.

Larger antennas many not help coverage unless you are located a larger HAAT.  You may also need downtilt in the antenna.

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Posted

I must have missed the "largest" part of the question.  LOL

 

Why do you want the largest antenna?  Wouldn't you want to best performing antenna for your needs, regardless of the size?

i was wondering that too...i'd been kind of monitoring the post, "best performing" within cost (and maybe size) contraints" would have been my first thought too, but i thought i might be missing something. 

 

if height (for performance) is the goal, couldn't that be handled more economically with more mast, rather than trying to get a bigger antenna?

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Posted

Learned a bit after posting this..

 

Mounting a 20' Mast on my 20'(off the ground) roof, now seeking the BEST performing and TALLEST GMRS antenna I can purchase. I have seen many antennas on the net, but nothing with outstanding gain. Any input?

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Posted

Learned a bit after posting this..

 

Mounting a 20' Mast on my 20'(off the ground) roof, now seeking the BEST performing and TALLEST GMRS antenna I can purchase. I have seen many antennas on the net, but nothing with outstanding gain. Any input?

I own a Comet 712EFC commercial GMRS antenna. It is an collinear design with omnidirectional horizontal coverage and 9dBi of gain, appropriate for me because my terrain is relatively flat.

 

A cheap antenna high in the air and above the trees and other obstacles will almost certainly outperform a premium priced antenna mounted low to the ground surrounded by such obstacles. Remember, antenna height is your friend.

 

Michael

WRHS965

 

 

 

 

 

 

Sent from my iPad using Tapatalk

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Posted

Data sheets say  "Comet 712EFC" is a Repeater antenna...can I use it as a simple base station antenna at 50 watt, no repeater?

 

Cheaper = Comparable to the 712EFC?  (Comet Original GP-1 146/446 MHz Dual Band Heavy-Duty Fiberglass Vertical Base Antenna - 4' 2", SO-239 Connector)

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Posted

Data sheets say  "Comet 712EFC" is a Repeater antenna...can I use it as a simple base station antenna at 50 watt, no repeater?

 

Cheaper = Comparable to the 712EFC?  (Comet Original GP-1 146/446 MHz Dual Band Heavy-Duty Fiberglass Vertical Base Antenna - 4' 2", SO-239 Connector)

Yes, you can use it as a base antenna.

 

The GP-1 is a ham antenna, and won't work (as well) on GMRS.

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Posted

So ... for maximum reception and range, you'd want a Yagi or Reflector type on a 20' mast and a rotator, then you can point and shoot with it, or to build and tune it yourself to your exact specifications.

 

Assuming you want a more normal COTS omni vertical antenna, then I'm going to be pretty simple about this: grounding/radials/the second half of the dipole and getting the height above the antenna's ground plane, as well as accounting for any obstacles (including rain gutters and guy wires) to be correct is more important than the nominal dBi gain of the antenna itself.  Something like that J-Pole above (they also exist tuned for GMRS) or with radials will do pretty well in this situation, as well as folded or vertical dipoles, or some other good designs.

 

But 50W into a cheap radio just simply isn't much power or selectivity to work with, be stuffing into one of these no matter what you do, and you're going to hit tropospheric propagation limits or receiver selectivity limits at maximum legal antenna height well before you run out of antenna gain.

To put it simply: with the current quality of GMRS radios and antenna height restrictions, any decent commercial vertical omni for the 460-470 MHz range, installed correctly, is going to perform about the same.  Choose based on what is going to work for your location rather that what has the theoretically best dBi or dBd, and read the manufacturer information (and maybe the ARRL Antenna book).  If you really want high performance, you'll build the antenna yourself.

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Posted

The 712EFC will work as a repeater antenna and base station antenna. I bought it for use as a base station antenna.

 

If you use a J-Pole Antenna it will work too, as long as you get one that is made for GMRS. J-Poles are designed to normally work on two different frequency bands, the 712EFC is designed for GMRS.

 

The gain of the two antenna’s are different. Both are omnidirectional horizontally. Both will work at 40’.

 

Michael

WRHS965

 

 

Sent from my iPad using Tapatalk

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Posted

Diamond and Comet are the two top brands I use for both base and mobile communications. You won't go wrong with the Comet 712EFC or the Diamond x300. They are both designed to perform well on the top end of the band. I have the x50 and the x200 and have posted real-world SWR and performance data from my system in the past.

 

The GP-1 doesn't have the gain that the 712 and the x300 do. Its 6db compared to 9db. If you life in an area that doesn't have a lot of tall hills or mountains, I would go with the higher gain antennas.

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Posted

Thanks!

 

Diamond BC-205 Antenna is being suggested by a shop over the Comet 712EFC or the Diamond x300. Not sure what to make of the advice...any input on the choice?

 

 

The 205 is a discontinued antenna that has a very narrow bandwidth and has to be tuned to the center frequency you want to use it on.  The x300 has almost double the bandwidth without having to tune it.

 

He is probably stuck with old inventory, which is the only reason I can think of that a shop would suggest a discontinued antenna that doesn't perform as well as a no-tune required, current production model.

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