I've read that when building a basic 1/4-wave antenna on VHF, the radials should be about 1/4-wavelength, or about 19.5", depending upon the exact frequency you're using. If we think of the radials as playing the role of a dipole's bottom-half, that makes sense to me.
But I've also read that if you're adding radials to a dual-band antenna (VHF and UHF), you can just use one set of radials, which are trimmed for the length of the larger/longer wavelength. So in this case the 19.5" radials would work fine for the UHF performance of the dual-band antenna.
Is this true? Does that mean that radials have a minimum length, but not maximum length? Or is it just a trade-off, and you get better performance when the radials are trimmed to match the length of whatever wavelength you're transmitting?
But I've also read that if you're adding radials to a dual-band antenna (VHF and UHF), you can just use one set of radials, which are trimmed for the length of the larger/longer wavelength. So in this case the 19.5" radials would work fine for the UHF performance of the dual-band antenna.
Is this true? Does that mean that radials have a minimum length, but not maximum length? Or is it just a trade-off, and you get better performance when the radials are trimmed to match the length of whatever wavelength you're transmitting?