There is at least one other antenna technology useful for aiming RF transmissions: NFDAM (Near Field Direct Antenna Modulation). Typically, a continuous carrier is sent to the antenna and there a digital signal is used to select an element from a 1 or 2 dimensional feed array that modulates the far field direction of the signal with the intended data. When properly applied only the signal in the desired direction (to the intended receiver) can be reconstructed (or even detected).

On Thu, Oct 1, 2020 at 6:55 PM jim bell <jdb10987@yahoo.com> wrote:

Yes. Weeks ago, I concluded that Starlink was probably using a "phased-array" IC for the ground station, so that the beam could be electronically steered. (The same IC that is being used for the Walabot sophisticated 'stud-finder'. https://www.amazon.com/Walabot-Imager-Android-Smartphones-Compatible/dp/B06Y29NXKK )

This is important, because they don't want the outputs of millions of such devices to be simultaneously emitted in ALL directions. THAT is a major advance, and it makes what they are trying to do practical.

Jim Bell