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Milligan T.,8204 W Polk Pl | Kaifas T.N.,Aristotle University of Thessaloniki
IEEE Antennas and Propagation Magazine | Year: 2014

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. © 1990-2011 IEEE. Source


Milligan T.,8204 W Polk Pl | Granet C.,BAE Systems | Kot J.S.,BAE Systems | Davis I.M.,BAE Systems
IEEE Antennas and Propagation Magazine | Year: 2013

Direct spillover from the feed past the edge of the subreflector can create sidelobes that exceed the sidelobe template requirements for typical SATCOM ground-terminal dual-reflector antennas. Some ¿rules of thumb¿ are given to the antenna designer for choosing the subreflector edge-illumination taper, to ensure that the design of the dual-reflector optics shaping does not create spillover past the subreflector that would be above the required sidelobe mask for transmitting operations. © 2013 IEEE. Source


Milligan T.,8204 W Polk Pl | Lopez A.R.,ARL Assoc.
IEEE Antennas and Propagation Magazine | Year: 2014

There are two antenna-bandwidth def nitions that are sometimes confused. These def nitions are for the antenna half-power bandwidth (HPBW) and the antenna impedance-matching bandwidth (IMBW). These are def ned below. © 1990-2011 IEEE. Source


Milligan T.,8204 W Polk Pl | Jones T.O.,System Center Pacific
IEEE Antennas and Propagation Magazine | Year: 2014

Arrays of two and four horizontal dipoles were used to achieve higher efficiency and vertical gain for several conductivities. These designs were compared to a single horizontal dipole. The four-horizontal-dipole array could be pointed 34° away from the vertical. The efficiency was reduced by only 1 dB. The groundwave was computed for all of the designs. The peak magnitude of the groundwave did explain the improved antenna efficiency. The antenna efficiency could be dramatically improved by increasing the antenna's height or operating frequency. © 1990-2011 IEEE. Source

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