Base Station Antenna Question

[Asheville1]

I live deep in cove with mountains on 3 sides, but I do have 90 degree and 20-25 mile line of sight to the S/SW. There are two repeaters in that direction that I want to try to reach.   Any suggestions on antenna?  Planning to purchase a 50 watt mobile for my base. Thanks!

[Socalgmrs]

A directional yagi might be best at 12db gain.

 

Or a comet712efc at 9db gain if you still want to transmit in 360deg 

[WSBZ540]

I would recommend a yagi myself. GMRS being split, the yagi will probably be tuned in the center between 462mhz and 467mhz. I would retune it to the frequency of the repeater. I can easily do simplex on a yagi 40 miles if the yagi is tuned to the simplex frequency. It still works if its center tuned, but its got some static in it. If you're industrious you can build your own. Ive built quit a few I can share plans on. 

[WRVR303]

I live in a hollow and am surrounded on three sides.

If it is truly line of sight to the repeaters, at 20-25 miles you probably don't even need a Yagi. If you want a "One and Done" solution, then the Yagi should  be your first choice. If are also planning on eventually having a mobile unit in a vehicle, you could start with a mobile antenna on a piece of 2'x2' sheet metal just to see how good your Tx/Rx is.

If you haven't already done this, a web site such as www.heywhatsthat.com lets you map the elevation profile between you and the repeater to see just how straight a shot it is.

This image shows the terrain between my house and a nearby repeater. A 5W handheld with the stock antenna can barely hit the repeater; a 40W mobile with a 5dB Laird antenna on sheet metal on my porch is very clear. The same 5W handheld going through 70' of 1/2" hardline coax to a 5dB Laird on my roof is very clear on the repeater. (The antenna on the porch has to transmit "through" the house to get to the repeater.)

[WSAA254]

if you really are line of site, then you should not have a problem hitting the repeater.   Elevation is everything.  I have attached a elevation chart to the repeater I use.  its about 50 miles away, and I can hit it consistantly on 5 watts.  i use a general purpose antenna --- compactenna scan III.  I also use a sdr with it.  I think there are better gmrs purposed antennas.   I have a swr of about 1.1 - 1.4 depending on frequency in gmrs.  My antenna is only about 10ft in the air.   We have really hi winds here so antenna size and height are a concern.  At gmrs frequencys I would recommend using a low loss coax (lmr 400)..  Best of luck

[kidphc]

I live deep in cove with mountains on 3 sides, but I do have 90 degree and 20-25 mile line of sight to the S/SW. There are two repeaters in that direction that I want to try to reach.   Any suggestions on antenna?  Planning to purchase a 50 watt mobile for my base. Thanks!

Whatever antenna you choose. You are going to want it roughly 100 feet up.

Make sure there is nothing in the way, you will want to try to clear as many trees, hills and buildings. The less obstructions the better you are. Really helps if the repeater antenna is just as high or if not higher.

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