Abstract: The multiple beam, short wave planar antenna array system, which simultaneously exhibits low loss, low side lobe levels, high efficiency, and low volume in a design affording independent control of the E and H plane radiation pattern shapes is particularly applicable in microwave radiometric systems such as airborne mapping systems. The antenna system generates symmetrical, matching narrow pencil beam sensitivity patterns by using symmetrically spaced sectorial receiver horns fed energy through a hyperbolic dielectric lens, the horn array and lens residing in a TE.sub.01 mode parallel plate guide, the lens being illuminated by signals collected by a broad wall slotted wave guide array supplied with a thin, planar sheet radome mounted on the energy receiving face of the array.