A millimeter wave circular polarized microstrip antenna based on linear polarized subarrays

A millimeter wave circular polarized microstrip antenna based on linear polarized subarrays is presented in this paper. The subarrays provide orthogonal vertical linear polarized component and horizontal linear polarized component. LHCP and RHCP waves can be obtained by configuring amplitudes and phases of the feeds. This microstrip antenna has relatively simple feed structure. In this microstrip circular polarized antenna, the ratio primary polarization to cross polarization change coincident with angle ¿. The cross polarization of this antenna is less than -15 dB in ±2°. The axial ratio is better than 3 dB in ±2° beam width.