False track discrimination in the sidelobe region of a monopulse antenna

In a monopulse radar system comprising a monopulse antenna array developing a main sum beam, a main difference beam, at least one sidelobe sum beam and at least one sidelobe difference beam, and wherein said main sum beam is wider than said sidelobe sum beam, a method for discriminating against false sidelobe tracking, comprising a sequence of the following steps:

• forming first monopulse sum and difference beams pointing at a first beam pointing angle;
• processing said first monopulse beams to detect a potential target track at an approximate potential target angle relative to said first beam pointing angle;
• calculating a first ratio of said first difference beam and said first sum beam at said first beam target angle;
• forming second and third monopulse sum and difference beams at respective second and third beam pointing angles offset from said first pointing angle;
• processing said second and third monopulse beams to detect second and third beam potential target tracks corresponding to said first beam target track;
• calculating a second ratio of said second difference beam and said second sum beam;
• calculating a third ratio of said third difference beam and said third sum beam;
• and
• accepting or rejecting said potential target track as a true target track in dependence on characteristics of said first, second and third ratios to exploit the difference in widths of the respective main sum and sidelobe sum beams.

In a monopulse radar system comprising a monopulse antenna array developing a main sum beam, a main difference beam, at least one sidelobe sum beam and at least one sidelobe difference beam, and wherein said main sum beam is wider than said sidelobe sum beam, a method for discriminating against false sidelobe tracking, comprising a sequence of the following steps:

• forming first monopulse sum and difference beams pointing at a first beam pointing angle;
• processing said first monopulse beams to detect a potential target track at an approximate potential target angle relative to said first beam pointing angle;
• calculating a first ratio of said first difference beam and said first sum beam at said first beam target angle;
• forming second and third monopulse sum and difference beams at respective second and third beam pointing angles offset from said first pointing angle;
• processing said second and third monopulse beams to detect second and third beam potential target tracks corresponding to said first beam target track;
• calculating a second ratio of said second difference beam and said second sum beam;
• calculating a third ratio of said third difference beam and said third sum beam;
• and
• processing said first, second and third ratios to accept or reject said potential target track as a true target track in dependence on characteristics of said ratios to exploit the difference in widths of the respective main sum and sidelobe sum beams, said processing comprising rejecting said potential track if said ratios are not of the same sign, and rejecting said potential track if respective magnitudes of said first, second and third ratios do not monotonically increase or decrease.