High-Gain Circularly Polarized Array Antenna With Low Grating Lobe Property Based on TM30/TM03 Mode

Abstract

In this letter, a high-gain circularly polarized (CP) array antenna with low profile and low grating lobe property is proposed. The array is composed of high-gain and low sidelobe CP patch elements based on odd high-order modes. By adding perturbation structure, a pair of orthogonal modes (TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">30</sub> /TM <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">03</sub> ) of the patch with 90° phase difference is diagonally excited. Meanwhile, by introducing five circular slots on the patch, four sidelobes of the element radiation pattern in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</i> o <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">y</i> o <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">z</i> plane are effectively reduced. Consequently, the large grating lobes of array antenna can be avoided. Then, a 2 × 2 array prototype is designed and fabricated for verification. The thickness of array is only 0.5 mm (0.027 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ). The peak gain and aperture efficiency reach up to 17.5 dBic and 55.5%, respectively. When the element spacing is more than 1 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">λ</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , the measured maximum grating lobe level at 16.25 GHz is only −15 dB.