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A deterministic method for the design of direct radiating arrays for multibeam satellite applications is presented in the current work. The method embodies the following steps: First, we consider the problem of continuous aperture synthesis, subject to directivity-pattern mask constraints. We succeed in stating the problem as a convex magnitude antenna design that exhibits a second-order cone program form. The solution provides the optimum continuous aperture current-density distribution. Second, exploiting the optimum solution, analytical formulas, in the form of the Pareto front, are presented through which the proposed method determines the minimum number of radiating elements that must be used in the process of transforming the continuous aperture to an antenna array. Third, an effective deterministic sampling approach is contributed to produce a discrete array with the desired characteristics. Armed with the above, the current work provides a generalized framework for the design of direct radiating arrays for multibeam satellite applications. The method is validated by the provided design examples.

In this article, the design of a cylindrical beamforming array (CBA) is presented. The array is conformed over a ring of a conducting circular cylinder. From the total number of elements, M, of the array, a subset of N successive elements is enabled each time. The selection of the subset is based on the minimization of the angle between its broadside direction and the direction of arrival (DOA) of the signal of interest (SOI). Furthermore, by adaptively combining the outputs of the active subarray, the gain of the system is maximized. The cylindrical beamforming array is integrated into the CDMA acquisition phase, where a joint process of code acquisition and smart-antenna adaptation is applied. The array is implemented for the uplink of a base-station receiver of a wireless communications system. A detailed justification and a performance evaluation under various simulation scenarios, which include integration into spatial and two-dimensional rake receivers, are also presented.

A Butler matrix (BM) for UMTS applications is presented. The Butler matrix was fabricated by conventional photolithography on a single laminate. The design is compact and complies with the required bandwidth. The design is based on the use of an elliptical coupler with certain geometrical characteristics, and a Lange coupler as a crossover. Furthermore, a design-scaling procedure that produces an N times N Butler matrix by using two (N/2)times(N/2) Butler matrices is given. The presented performance extrapolations clarify the potential and scalability of our approach