Multi-beam antenna using higher-order modes

An array antenna comprising:

• a first array structure including a plurality of first array elements consisting of a first central element and first peripheral elements configured to surround the first central element, each of the first central element and the first peripheral elements being a first waveguide, and the first peripheral elements exciting higher-order modes through first coupling slots to form a beam pattern by electric field distributions of the first central element and the first peripheral elements;
• a second array structure including a plurality of second array elements consisting of a second central element and second peripheral elements configured to surround the second central element, each of the second central element and the second peripheral elements being a second waveguide, and the second peripheral elements exciting higher-order modes through second coupling slots to form a beam pattern by electric field distributions of the second central element and the second peripheral elements,
• wherein:
• half of an aperture of each of the first peripheral elements proximal to the first central element has a same phase as an electric field of the first central element;
• and
• half of an aperture of each of the first peripheral elements farther away from the first central element has an opposite phase to the electric field of the first central element,
• wherein:
• half of an aperture of each of the second peripheral elements proximal to the second central element has a same phase as an electric field of the second central element;
• and
• half of an aperture of each of the second peripheral elements farther away from the second central element has an opposite phase to the electric field of the second central element, and
• wherein a zero point is generated at a center of each of the apertures of each first and second peripheral elements.