Design of Monopulse Antenna Difference Patterns with Low Sidelobes

Monopulse radar systems have, in recent years, achieved a high degree of flexibility in their antenna patterns. This flexibility is the result of development of multihorn feed structures and array antennas. It now appears feasible to optimize independently the sum and difference patterns of the monopulse system. A good deal of work has been done to improve the sidelobe performance for sum beam pat* This work was supported by the Army Materiel Command under Contract DA-30-069-AMC-333(Y) through the Nike-X Project Office, Redstone Arsenal, Alabama. 623 624 T H E BELL SYSTEM TECHNICAL JOURNAL, M A Y - J U N E 1 ! ) ( 5 8 terns. 1 However, less attention has been paid to improving the angle sensitivity and sidelobe performance of the circular aperture difference pattern. The objective of this investigation was to develop a difference pattern which possesses characteristics that are compatible with those of the Taylor sum pattern. Specifically, the goal was to obtain the maximum angle sensitivity commensurate with a given sidelobe level. Low sidelobes are desirable in both sum and difference patterns for the suppression of near-target clutter, ground clutter, and jammers. Requiring large angle sensitivity and low sidelobes for the difference pattern is analogous to requiring a narrow beamwidth and low sidelobes in the case of the sum beam. The pattern that meets these requirements must be produced by a reasonably well behaved aperture illumination. This paper solves the problem of generating difference patterns by using a technique that parallels Taylor's approach to the sum pattern design.