Ground-based satellite communications nulling antenna

A method for directing a ground-based antenna having a radiation pattern comprising a plurality of nulls and a plurality of lobes generated from a uniformly illuminated aperture having a horizontal dimension and a vertical dimension, on a plurality of geosynchronous earth orbit satellites equally spaced by an angle subtended by the center of the earth, comprising the steps of:

• calculating the horizontal dimension of the aperture so that the plurality of nulls of the radiation pattern align with the plurality of geosynchronous satellites;
• determining a location of the ground-based antenna on an earth surface, that causes the nulls of the radiation pattern to fall out of alignment with the plurality of geosynchronous satellites;
• calculating an angle of rotation about a transmission axis extending normally from the aperture to at least one geosynchronous earth orbit satellite to realign the plurality of nulls of the radiation pattern with the plurality of geosynchronous satellites, wherein the angle of rotation is dependent upon the location of the ground-based antenna on the earth surface;
• and
• rotating the aperture about the transmission axis by the angle of rotation to realign the nulls of the radiation pattern with the plurality of geosynchronous satellites.

A satellite communications system, comprising:

• a plurality of geosynchronous earth orbit satellites equally spaced in an equatorial arc around the earth;
• and
• a ground-based antenna having a radiation pattern transmitting a first frequency at a first polarization, the radiation pattern comprising a plurality of lobes separated by a plurality of equally spaced nulls, wherein at least one lobe is directed along a transmission axis from the antenna to a first satellite of a plurality of geosynchronous earth orbit satellites,
• wherein the ground-based antenna has a first dimension proportional to the separation between each equally-spaced null, such that each of the plurality of equally-spaced nulls are directed on at least one of the plurality of geosynchronous earth orbit satellites adjacent to the first satellite.