Patent ID: 6218985
Filing Date: 2001-04-17
Classification: H01Q

Abstract:
A method for steering a beam for an antenna array comprising the following steps:calculating for each antenna element of an active sector of an antenna array an amplitude weight and a phase shift angle of a transmit signal that minimizes an error function of a desired beam pattern of the antenna array relative to a calculated beam pattern,wherein the error function is calculated as follows: ##EQU5##wherein:I.tbd.mean square beam pattern error;M.tbd.number of azimuth angles for which the electric field values of the antenna elements are known;F.tbd.desired electric field of the antenna array;.phi..sub.m.tbd.one of M azimuth angles for which the electric field values of the antenna elements are known;n1.tbd.first element of the active sector;n2.tbd.last element of the active sector;B.sub.n.tbd.complex current input to the n.sup.th antenna element;Z(n,m)=e.sub.n (.phi..sub.m -.phi..sub.n)exp(2.pi.jf{x.sub.n cos(.phi..sub.m)+y.sub.n sin(.phi..sub.m)}/c);e.sub.n (.phi..sub.n).tbd.a normalized electric field of the n.sup.th antenna element;x.sub.n,y.sub.n.tbd.location of the n.sup.th antenna element;j.tbd.-1;f.tbd.transmit signal frequency; andc.tbd.speed of light;weighting the transmit signal for each antenna element by a selected amplitude weight approximating the calculated amplitude weight; andphase shifting the weighted transmit signal for each antenna element by a selected phase shift angle approximating the calculated phase shift angle.