Abstract: A dual mode R.F./IR seeker suitable for use in an anti-radiation missile is disclosed. The infrared sensor is responsive to radiation within the 4.0 to 4.8 micron band and the radio frequency sensor is responsive to radio frequency signals within a 6.5 to 16.5 GHz band. The infrared sensor comprises a folded Cassegrainian telescope arrangement, including a primary mirror which is transparent to radio frequency energy. The radio frequency sensor comprises an annular array of orthogonally disposed stripline flared notch radiating elements. A broadband microwave receiver, fabricated in a multilayered stripline package, is provided for forming radio frequency monopulse sum (?) and difference (?) signals and for converting such radio frequency monopulse signals to suitable intermediate frequency signals for processing in an I.F. receiver. The infrared and radio frequency sensors share a common aperture and optical axis.

Abstract: An improved slot array antenna with a circular aperture and linear polarization is shown to be made up of a plurality of slotted waveguides having different lengths and different widths. The slots in the waveguides are positioned to optimize amplitude taper in any plane passing through the center of the array normal to the surface thereof and to maximize the number of such slots.