1
$\begingroup$

When I was deployed, our commo guys gave us wire antennas we could thread through our body armor (through the MOLLE loops). These antennas were just lengths of 50Ω coax that had the insulation stripped leaving the insulated core. ostensibly these antennas would have been tuned for our radios, but I would like to recreate one for my HT while hiking.

Here's the rub, I have a commercial license band around 485 Mhz, but also want to be able to use the same antenna for 2m/70cm MURS, FRS/GMRS (Yes I have the GMRS license too)

I calculate that a 7/8λ antenna for my commercial channel would need to be about 20", but a 2 meter 1/4λ would need to be just around 19".

I get that the difference of these are below the fractional wavelength, so, the 20" for the commercial freq would work for the 2m. But wanted to get some feedback from some people smarter than me to make sure this would work.

Thanks!

$\endgroup$

1 Answer 1

3
$\begingroup$

If it is on your body or within a close range of it, the resonant length would vary wildly and you may not be able to get a close match on multiple bands. I suggest try long IE ~4-5 ft and cut shorter until a low SWR is achieved at the top end of the 440-MHz band. A 70cm antenna cut for the US band usually presents an adequate match on GMRS. However, an on-the-body antenna has a lot of loss due to capacitance, you would do well to use a separate mic and the "rubber Duck" or whip antenna from the HT.

If you follow through on the body antenna idea, I wouldn't advise running more than 5 or so watts because of the risk of RF burns. Other than that, it may work! Good luck with your endeavors!

73 AI7OW

$\endgroup$
1
  • $\begingroup$ Excellent, thanks! I knew I was overlooking something (body interference) if I thread it through my plate carrier it will be pretty close, so I'll definitely try longer than needed. Fortunately the radios I have are all 5w,with one or two that get as high as 8. Thanks again! $\endgroup$ May 12, 2023 at 20:41

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .