Originally Posted by
EDLB
For the GPS frequencies from 1175 to 1575MHz those single cones do not yield much directivity. Because they are not much larger than the wavelength. I would guess that directivity/gain is less than 10dB for a single cone, so given the necessary power of a jammer you an neglect the directivity.
Since they don't know the direction of the incoming threat, they do have to cover a very wide beamwidth in total.