Abstract: A conical microstrip antenna carried by a frustum of a cone with a half-angle at the apex .alpha., height H.sub.0 and a circular reference line of radius R, includes an annular succession of N radiating patches disposed on the frustum and divided into at least one sub-array of radiating patches connected with equal phase by a respective tree-structure feed array to the same common point, the N radiating patches being made on a dielectric material to resonate in a predetermined frequency band having a center frequency Fo. The tree-structure array is formed of n stages each including dividers of the same order, either the second order or the third order. When developed onto a flat surface, the dividers within the same stage i are made up of an integer number of substantially identical straight line segments with equal angles .gamma.

Abstract: An array antenna embodying on a dielectric support, a periodic succession parallel to an alignment direction of rectangular patches having alternating active patches and parasitic patches. The active patches are identical, fed with electromagnetic energy in areas such that their sides parallel to the alignment direction are radiating sides, sized to have the same resonant frequency and disposed so that their phase centers are at a distance apart less than the wavelength in air associated with the resonant frequency. The parasitic patches are separated from the active patches by slots of constant non-null width extending transversely to the alignment direction and sized to have resonant frequencies near the resonant frequency of the active patches.

Abstract: An elementary antenna embodies a constant thickness dielectric substrate having on one side a conductive metal layer forming a ground plane and on its other side a radiating patch electrically connected to a feed line. The patch is formed by a conductive loop of constant width l surrounding an inner parasitic patch which is not fed and is separated from the inner parasitic patch by a closed continuous slot of constant width e adapted to bring about coupling between the loop and the inner parasitic patch.