Microwave receiving antenna array having adjustable null direction

A microwave receiving antenna array for providing maximum response to incident microwave radiation arriving from a primary receiving direction while rejecting incident microwave radiation arriving from a null-reception direction which differs from said primary receiving direction by only a small angle, comprising:

• identical first and second parabolic reflector antenna elements individually directed in said primary receiving direction and collectively disposed in a plane perpendicular to said primary receiving direction, each one of said first and second parabolic reflector antenna elements having a polarization direction and each one of said first and second parabolic reflector antenna elements including a low-noise amplifier means providing an electrical output signal representative of the amplified component of said microwave radiation received by the associated one of said first and second parabolic reflector antenna elements;
• first and second phase-shifting transmission line means having input and output ends, respective ones of said input ends operably connected to a respective one of said antenna elements to accept one of said electrical output signals for presenting phase-shifted output signals at said output ends, the phase-shifts introduced to said respective electrical output signals by their associated transmission line means being equal;
• means for additively combining said phase-shifted output signals at said output ends of said first and second phase-shifting transmission line means to produce a composite output signal therefrom and for delivering said composite output signal to an output transmission line means, said means for additively combining and delivering including impedance-matching means operably interposed between said first and second phase-shifting transmission line means and said output transmission line means to effect an impedance match therebetween;
• means for individually rotating said polarization direction of said first and second parabolic reflector antenna elements about an axis parallel to said primary receiving direction to maximize response to incident microwave radiation arriving from said primary receiving direction;
• and
• means for collectively rotating said first and second parabolic reflector antenna elements about an axis through a point half-way between said elements and parallel to said primary receiving direction to adjustably vary said null-reception direction therewith.

A method for receiving incident microwave radiation from a primary receiving direction while rejecting incident microwave radiation from an adjustable null-reception direction differing from said primary receiving direction by a small angle comprising the steps of:

• symmetrically arranging a plurality of directional antenna elements about a geometric center point in a common plane perpendicular to said primary receiving direction, each individual one of said plurality of directional antenna elements providing an output signal at a particular impedance level;
• directing each individual one of said plurality of directional antenna elements in said primary receiving direction;
• phase-shifting each said output signal by an equal amount to provide a plurality of equally phase-shifted output signals having a common impedance level;
• combining said plurality of equally phase-shifted output signals and transforming said common impedance level to form a single composite output signal at an output impedance level;
• coupling said single composite output signal to an output transmission line having a characteristic impedance which matches said output impedance level;
• and
• collectively rotating said plurality of directional antenna elements about an axis through said geometric center point and parallel to said primary receiving direction to adjust said adjustable null direction thereby.