I'm curious as to the ability of an antenna designed for a specific wavelength, to work on another wavelength. For example, I have a half wave antenna that is 1.5m long, which would be ideal for a 100MHz signal. Now would that same 1.5m antenna work well on a 150MHz signal, or an even higher frequency? At what point would it no longer work? Are there any quantities that are minimized?
An antenna that resonates at one frequency (e.g., 100 MHz) will also resonate at odd multiples of that frequency (e.g., 300, 500, MHz, etc.). However, the radiation pattern will be different on each of those frequencies. At the lowest frequency, the maximum sensitivity will be broadside to the wire. At higher frequencies, it will shift toward the ends of the wire.