Millimeter-Wave Endfire Wide-Angle Scanning Circularly Polarized Antenna Array

Because the width of antenna elements exceeds half of the air wavelength, resulting in too large element spacing, the scanning angle of traditional endfire circularly polarized (CP) antenna array is usually less than 60°. In order to solve the above problem, a CP quasi-Yagi antenna element is proposed in this letter, whose width is less than half of the air wavelength. Further, an 1 × 8 endfire CP antenna array is designed. Because the element spacing is about half a wavelength, the scanning angle of the proposed endfire CP antenna array can reach 60°. Moreover, the axial ratios of all beams are less than 3 dB in the scanning angle range of (0°, 60°). The final measured results are basically consistent with the simulated results