[1] A method for ensuring polarization agility in conjunction with beam steering in planar array antennas is proposed. It relies on interleaving two subarrays with orthogonal, linear polarizations that, together, can generate arbitrary polarization states: adjustable linear, elliptical, and left-or right-handed circular. The complexity of the resulting system is comparable with that of standard, fully populated array antennas consisting of identical, linearly polarized elements. By dynamically controlling the amplitude and the phase of the signals fed to the subarrays, a stable polarization state can be maintained during beam steering. The concept is validated by numerically investigating an architecture obtained by interleaving nonuniform subarrays designed by means of a deterministic placement strategy. The effects of the mutual coupling between the different radiating elements are modeled and discussed.Citation: Simeoni, M., I. E. Lager, C. I. Coman, and A. G. Roederer (2009), Implementation of polarization agility in planar phased-array antennas by means of interleaved subarrays, Radio Sci., 44, RS5013,

Abstract-A consistent strategy for the design of finite array antennas consisting of differently sized radiating elements is discussed. In view of increasing the total bandwidth of the antenna system, while maintaining a low mutual coupling between the elementary radiators, sparse subarrays, operating at adjacent frequency ranges, are interleaved on a common (shared) aperture. The sparse architectures are designed using a combinatorial method that ensures an acceptable behavior in the side-lobes region in conjunction with a narrow beamwidth. The effect of the mutual coupling between identical and differently sized elements is accurately evaluated and is accounted for in predicting the performance of each individual radiator. The concept is illustrated by designing a shared aperture antenna consisting of two interwoven subarrays that jointly cover a fractional bandwidth of 14% in the X-band. Cavity-backed, stacked-patches antennas with coaxial feeding are used as elementary radiators.Index Terms-Mode-matching methods, shared aperture, sparse array antennas.

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Abstract-A new family of structures launching the fundamental mode in rectangular waveguides is proposed. Individual or stacked cavity-backed patch antennas radiate into a rectangular waveguide, providing a good matching with a coaxial input over a wide frequency range. The configuration results in a very compact, colinear transition from a standard coaxial connector to a rectangular waveguide. The components have applications as general-purpose coaxial-to-rectangular waveguide transitions and are well suited for low-profile, phased-array antennas. Experimental results confirm the computational estimations of the proposed components' performance.

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