It works two ways: one is that you can go lower in frequency (e.g. bigger wavelength) if your dish is bigger, the other is that you just capture more of the sig

It works two ways: one is that you can go lower in frequency (e.g. bigger wavelength) if your dish is bigger, the other is that you just capture more of the signal. If you take light as a metaphor, a bigger lens will just provide more 'signal' at the focal point.