Want to set up my place with an external antenna for a SHTF home base. Is there an external antenna that covers both the dual bands on the UV5R or am I gonna need separate J-pole and GMRS antennas? TIA!
for this kind of thing - a discone is a sensible coice that will let you operate on a very wide range of frequencies - J-poles are a bit narrow banded - they have a very limited range where they are efficient. Ordinary dipoles have a wider bandwidth.
Things like ¼ wave VHF antennas with a groundplane are pretty good as a ¾ wave for UHF
A dual band J-Pole will cover 2M and 70cm. GMRS iis in the 70cm band. I build dual band J-Poles for VHF/UHF from 1/2" copper pipe. Many people use these of the 70cm copper J-Pole for their GMRS operations. One operator got one from me and is using it on his GMRS repeater. He has no problem with it.
Thanks for the help! Ended up going with a Comet GP-3.
I never found j-poles to be that good when trying to make them dual band. Some of the designs are sort of J-poles, but there are so many designs it’s difficult to know what we’re looking at. The ideal of a half-wave antenna that gets the high impedance converted with a stub. I get how you can do dual band with the ones that are 300Ohm ribbon feeder with little nibbles out of them - but Some of the designs seem to be quarter waves, with one a sort of parasitic one - I have no idea how these things really operate, but they must, because people buy them and seem to like them, but most have very scanty specs - and the ones that consist of three separate elements must have very odd polar patterns. The manufacturers of the commercial ones are very scant with details. You can make antennas that match impedance, and give a great VSWR reading, but are just rotten antennas, and good antennas that have very tricky matching. J-Pole is a very oddly specified antenna - so many different types that all have the same name but are really different. ¼ waves work well on 3 times their frequency, but half-wave (which J-poles usually are) work differently. I have some marine fibreglass antennas I use that are groundplane-less, and I suspect they’re based on J-pole traditional designs - but I’ve never cut one up to find out!
He’s a clever chap at antenna design, but rubbish at communications. The idea of releasing a zoom presentation with people in the room is a bit odd. If they had the slides, then a shame he didn’t give them the hi res recording of his image. He did find that weird arrow design fairly poor which was interesting. The clever version with the band stop stubs seems a good idea though.
This is very helpful.
Thanks for sharing this video, some very useful information and DR. Fong explains things in a very easy to understand way.