Supergain antennas and the Yagi and circular arrays

The characteristics of endfire, Yagi, and circular arrays of dipoles are reviewed with special reference to their directional properties and the possibility of supergain. The quantum-mechanical analog that suggested the investigation is described. The critical newly emphasized feature is the high-Q property of a correctly designed closed loop of coplanar dipoles when only one element is driven and all dimensions (the length of the elements, their cross-sectional size and shape, the number of elements, and the circumference of the closed loop array) are correctly chosen so that the entire array is adjusted to resonance. An immediate application to beam scanning is described.<
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