Tapered-element array antenna with plural octave bandwidth

An antenna for radiating electromagnetic power with plural octave bandwith is formed of an array of microstrip radiating elements each of which includes a microstrip conductor element spaced apart from a ground-plane element. A common ground-plane element is employed by all of the radiators in a row of the antenna, there being a plurality of the rows disposed parallel to each other. In each radiator, the microstrip conductor element is formed of an input section which is coupled to a feed, and an output section extending to an output end of the radiator for forming a radiating aperture of the radiator. In each output section, there is a two-dimensional enlargement of a cross-section of the radiator, one dimension of enlargement being parallel to the ground-plane element, and the other direction of enlargement being perpendicular to the ground-plane element. Enlargement in the direction parallel to the ground-plane element is accomplished by increasing the width of the conductor element. Enlargement in the direction perpendicular to the ground-plane element is accomplished by bending a portion of the conductor element away from the ground-plane element to provide for an inclination of the conductor element relative to the ground-plane element. Enlargement of the width may occur prior to or concurrently with enlargement of the dimension perpendicular to the ground-plane element.