Recommendations for VHF/UHF dual band inverted mount base antenna?

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xpr8300

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Hey all,

Got a project handed to me and need some advice. The local hammy group has been given permission to put an antenna on the monopole at the EOC (up about 100' or so). This will go to a dual band radio and not a repeater. The only mount that is available would require the antenna to be inverted. ARES wants to use a Hustler G6-270R. I am not hot on the idea but am coming up short on dual band commercial solutions. I would rather not have the antenna fly apart in a thunderstorm or even a tropical storm. What antenna would you guys recommend?

Thanks!
 

ndp

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We've had good luck with Diamond for hammy stuff. Have it about 90 feet up and it's survived many New England winters, tornado warnings, and assorted inclement weather without issue.

https://www.diamondantenna.net/x50na.html

Something like this might be the ticket for you, I'd certainly trust it more than the Hustler. It's done well for us.
 

Viper1-6

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If its for local repeater comms, and they are not looking to talk across the whole state on simplex, a Sinclair 210-C1 or C2 will load on UHF.
 

MotoBill

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I too have seen VHF arrays used on UHF with a dual-band diplexer. As you'd expect, the UHF gain is somewhat dismal but usually works locally with range dependent upon additional losses due to mismatch of impedance and effective height above average terrain.

If anyone is curious, I ran a single resonant half-wave dipole radiator at 146 MHz in EZNEC, and then again just above the third harmonic at 444 MHz to obtain a comparison of elevation patterns. The VSWR at the antenna on UHF is nearly 3:1, but when you toss in the losses of a phasing harness and transmission line under mismatched conditions, the actual load as seen at the input of the transmission line doesn't look horribly terrible. It's just lossy and radiates poorly toward the horizon.


Elevation pattern of vertical dipole resonant at 146 MHz.

VHF Elevation Pattern.jpg

Elevation pattern of same VHF vertical dipole at 444 MHz.

UHF.jpg
 
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CARC383

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If an antenna you have in mind is not specifically designed to be mounted upside down I would contact the mfr and get their opinion. Most fiberglass antennas cannot be mounted upside down and will fill with water. Many have drain holes for right side up mounting. I think the Hustler series has a drain hole at the bottom and if you mount that upside down it will probably collect every rain drop in the county.
 
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xpr8300

xpr8300

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This was my concern as well. Single band commercial antennas able to be inverted are common, not so much on dual band and i am doubting the hammy ones will. Without climbing up there to look, i am not sure there is enough spare cable to move one of the commercial antennas to an inverted mount so i can put up the hammy one right side up. Of course the customer is paying for the ham's stuff, so the hambones are asking for the moon and the stars. If it were up to the hams, they would have their own dedicated mounts installed at the top and move the public safety antennas down.
 
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