Abstract: An electromagnetic lens for a commutated scanning beam antenna has a plurality of petal-shaped parallel plate segments, connected in series, with the first petal-shaped segment adapted to receiver power at its input edge through an array of input probes connected, in a commutative switching arrangement, to a radio frequency transmitter. The last petal-shaped segment of the lens is formed into a radiating aperture or is connected to a linear array of radiating elements. Various techniques for determining petal shapes and for connecting together the petals are discussed. Stacked and folded lenses are described.