Millimeter-Wave Endfire Circularly Polarized Phased Array with Wideband Wide-Angle Scanning

An endfire circularly polarized (CP) phased array with wideband wide-angle scanning capability in the millimeter-wave band is proposed. The array elements consist of notched substrate integrated waveguide (SIW) dipole antennas with two metal plates, specifically designed for endfire radiation. The metal plates and two patches are employed to achieve wideband CP radiation. In addition, by incorporating a subtracted section and slotting the metal plates, the CP wide-angle scanning performance of the proposed antenna is significantly improved. To validate the design, a 1×16 array prototype is simulated, fabricated and measured. The measured results demonstrate that the proposed antenna can achieve ±45° scanning in 25–32.5GHz (26.1%) and ±60° scanning in 26.2–30.5GHz (15.2%), while maintaining active voltage standing wave ratios (VSWRs) below 3 and axial ratios (ARs) below 3dB. Moreover, the maximum scanning loss is approximately 4dB. The simulated and measured results show a good agreement.