It all depends^TM, mostly on the wavelength and the size and shape of the gap and the phase of the moon. dB is a logarithmic scale, so this kind of back-of-the

It all depends^TM, mostly on the wavelength and the size and shape of the gap and the phase of the moon. dB is a logarithmic scale, so this kind of back-of-the-envelope reasoning is sometimes made easier and sometimes counterintuitive.