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: A microwave phase discriminator is shown to include a microwave bridge network having two pairs of input ports and two pairs of output ports, the phase shift of signals passing through such network being dependent upon which one of the input ports is actuated, a diode detector connected to each one of the output ports, a difference amplifier connected to each pair of diode detectors, a single-pole double-throw switch connected to each input port and commutating switches at the inputs to the corresponding difference amplifiers.

Abstract: A matching section for a spiral antenna used in a monopulse receiver is shown to receive a plurality of coaxial cables at equally spaced points along the circumference of a first circle and to guide the center conductors of such cables to arms of a multi-arm spiral antenna at equally spaced points along the circumference of a second circle, the characteristic impedance along the length of the matching section changing smoothly for the sum and difference modes and impedance matching closely to the antenna sum and difference modes.

Abstract: A broadband antenna element capable of operating over greater than an octave band of frequencies is disclosed. The element comprises an open-ended rectangular waveguide section having a loop radiator, formed by shorting an insulated probe to one of the broad walls of the waveguide section, disposed therein. Notches are provided in the narrow walls and flanges are provided on the broad walls of the waveguide section for matching purposes. The insulated probe extends through a hole formed in the rear wall of the waveguide section to connect with a stripline feed network.