Antenna offset principal plane sidelobes for enhanced ground clutter suppression
An electromechanically steered passive directional arrays and ESA antenna with the rectangular apertures' mathematically separable radiation pattern array lattice rotated to rotate the higher cardinal plane side lobes to ±45° relative to the vertical plane. Rotation minimizes clutter returns that mask weaker power returns and generates larger mean side lobe path loss. The higher sidelobe power levels are directed away from the critical area along the runway during approach. Individual array elements may be counter rotated to maintain desired antenna polarization state.
1 . An ESA antenna apparatus comprising a plurality of radiating element, wherein:
the plurality of radiating elements are disposed in an array within a rectangular array lattice;
the rectangular array is configured to produce a first set of sidelobes along a cardinal plane and a second set of sidelobes along an intercardinal plane;
the first set of side lobes having a higher relative amplitude than the second set of side lobes; and
the array being disposed to direct the intercardinal plane at a runway during a landing procedure.
2 . The ESA antenna apparatus of claim 1 , wherein the array lattice is rotated by ±45°.
3 . The ESA antenna apparatus of claim 2 , wherein the radiating elements are electronically rotated to produce a polarization state corresponding to a polarization state of an unrotated co-polarized array lattice.
4 . The ESA antenna apparatus of claim 2 , wherein the radiating elements are electronically rotated to produce an arbitrary polarization state.
5 . The ESA antenna apparatus of claim 1 , wherein the radiating element's polarization states are electronically rotated to produce a polarization corresponding to a polarization state of an unrotated array lattice.
6 . The ESA antenna apparatus of claim 5 , wherein the radiating elements are electronically rotated to produce an arbitrary polarization state.
7 . A radar system comprising an ESA antenna comprising a plurality of radiating elements, wherein:
the plurality of radiating elements are disposed in an array;
the rectangular array is configured to produce a first set of sidelobes along a cardinal plane and a second set of sidelobes along an intercardinal plane;
the first set of side lobes having a higher relative amplitude than the second set of side lobes; and
the array being disposed to direct the intercardinal plane at a runway during a landing procedure.
8 . The radar system of claim 7 , wherein the array lattice is rotated by +45°.
9 . The radar system of claim 8 , wherein the radiating elements are electronically rotated to produce a polarization state corresponding to a polarization of an unrotated array.
10 . The radar system of claim 8 , wherein the radiating elements are electronically rotated to produce an arbitrary polarization state.
11 . The radar system of claim 7 , wherein the radiating elements are electronically rotated to produce a polarization state corresponding to a polarization state of an unrotated array.
12 . The radar system of claim 11 , wherein the radiating elements are electronically rotated to produce an arbitrary polarization state.
13 . The radar system of claim 7 , wherein the array is configured to rotate from a first orientation of 0° polarization state to a second orientation of ±45° polarization state.
14 . An aircraft comprising an ESA antenna comprising a plurality of radiating elements, wherein:
the plurality of radiating elements are disposed in an array;
the rectangular array is configured to produce a first set of sidelobes along a cardinal plane and a second set of sidelobes along an intercardinal plane;
the first set of side lobes having a higher relative amplitude than the second set of side lobes; and
the array being disposed to direct the intercardinal plane at a runway during a landing procedure.
15 . The aircraft of claim 14 , wherein the array lattice is rotated by ±45°.
16 . The aircraft of claim 15 , wherein the radiating elements are electronically rotated to produce a polarization corresponding to a polarization of an unrotated array lattice.
17 . The aircraft of claim 15 , wherein the radiating elements are electronically rotated to produce an arbitrary polarization state.
18 . The aircraft of claim 14 , wherein the radiating elements are electronically rotated to produce a polarization state corresponding to a polarization of an unrotated array lattice.
19 . The aircraft of claim 18 , wherein the radiating elements are electronically rotated to produce an arbitrary polarization state.
20 . The aircraft of claim 14 , wherein the array is configured to rotate from a first orientation of 0° polarization state to a second orientation of ±45° polarization state.