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Abstract

A satellite based signal transmission and reception system which generates multiple beams with low side lobes and minimal crossover losses. The system includes a focusing device and an array of signal generator elements coupled to feed radiator elements. The feed radiator elements are assigned into overlapping beam sub-arrays characterized by a frequency and radiated beam polarization. Each overlapping sub-array generates a transmission beam signal which is orthogonally polarized with respect to the beam generated by the other overlapping sub-array. The use of beam orthogonality provides for physically overlapping beam sub-arrays without the use of analog combining networks which are inherently lossy structures. This allows beams to be generated having a highly tapered amplitude distribution to simultaneously achieve low side lobe levels and low beam cross over losses. By employing multiple signal generators driving the transmission elements of the beam sub-arrays, the transmission system is able to step the transmit signals along the feed radiator array to compensate for satellite motion without the use of complex RF switching networks. In an analogous fashion, antenna elements in an array receive multiple transmission beam signals which are incident upon a focusing device. The antenna elements are dynamically assigned to overlapping receive beam sub-arrays which are orthogonally polarized. The multiple beam receiving system is able to step the received signal sub-arrays along the array to compensate for satellite motion.

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First Claim