A dual mode radar seeker comprising a wide-band passive anti-radar antenna system ( 3 ) at the rear of a radome ( 1 ), operating at relatively low radar frequencies in an amplitude comparison tracking mode, and a high-frequency (W-band) active amplitude-comparison antenna system ( 5 ) in the nose of the radome ( 1 ) and having a common boresight with the anti-radar system. The active system employs coarse phase shift steering ( 31, 41 ) of the antenna ‘beam’ for the transmit and, optionally, also, the receive ‘beam’. The high frequency and the use of phase shift steering both help to keep down the size of the active radar thus enabling it ( 5, 7, 9 ) to be positioned far forward in the nose of the radome ( 1 ) so as not to obscure the field of the anti-radar system ( 3 ).
1. A dual mode seeker comprising a missile radome having a longitudinal axis, a wide-band amplitude-comparison passive radar and a high-frequency phased-array active radar, said passive radar and said active radar having a common boresight aligned with said longitudinal axis and said active radar having an antenna mounted in the nose of said radome forward of said passive radar and being of small size commensurate with its high operating frequency such as to present negligible obstruction in the field of said passive radar.
2. A dual mode seeker according to claim 1 , wherein said active radar incorporates means for phasing both the transmitted and the received signals.
3. A dual mode seeker according to claim 1 , wherein said active radar incorporates phase shifting means operative at radar frequency to effect phasing of the received signals.
4. A dual mode seeker according to claim 1 , wherein said active radar incorporates phase shifting means operative at intermediate frequency to effect phasing of the received signals.
5. A dual mode seeker according to claim 4 , wherein said phase shifting means is constituted by electronic angle tracking circuitry.
6. A dual mode seeker according to claim 1 , wherein said active radar comprises transmitting and receiving circuitry and said antenna is connected to said transmitting and receiving circuitry by an axial feed extending through an antenna of said passive radar.
7. A dual mode seeker according to claim 1 , wherein the portions of said radome employed by the respective radars are constructed according to the frequency of operation and the physical and aerodynamic requirements of the respective locations on the radome.
8. A dual mode seeker according to claim 1 , wherein said active radar operates at millimetric wavelengths.