Vanishing Point
Well-Known Member
- Thread starter
- #1
So I think my math is okay but when I go to look for circular ground planes for sale for GMRS I see that folks (including some radio selling sites that I think are not in the consumer's best interest) selling 6" diameter discs as GMRS ground planes. I've even seen that mentioned on this site as being the correct size. That all you need is a 6" diameter disc. After doing the calculations I come up with needing about a 14" diameter disc.
GMRS frequency ~ 462 mhz
GMRS wavelength ~ 70cm
1/4 wavelength ~18cm
18 cm ~ 7 inches
So 7" should be the radius of the groundplane disc. I believe that you want the radius and not the diameter of your groundplane to be 1/4 wavelength. I kind of rounded up. I think if you do the math proper you can use a 6.5" radius disc.
Are my numbers wrong? I keep seeing the 6" diameter advice/disc for sale and keep wondering where I went wrong.
Sorry for posting this here, I don't belong to any of the HAM radio sites.
GMRS frequency ~ 462 mhz
GMRS wavelength ~ 70cm
1/4 wavelength ~18cm
18 cm ~ 7 inches
So 7" should be the radius of the groundplane disc. I believe that you want the radius and not the diameter of your groundplane to be 1/4 wavelength. I kind of rounded up. I think if you do the math proper you can use a 6.5" radius disc.
Are my numbers wrong? I keep seeing the 6" diameter advice/disc for sale and keep wondering where I went wrong.
Sorry for posting this here, I don't belong to any of the HAM radio sites.
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