No abstract

No abstract

No abstract

No abstract

A circularly-polarized (CP) 4×4 array antenna based on substrate integrated waveguide (SIW) technology is presented. Circular polarization is achieved by applying the sequential rotation technique (SRT) with a well designed sequential feed network and linear-polarized array elements. The proposed 4×4 array has a wide axial ratio (AR) bandwidth of 14% from 18.3 GHz to 21.1 GHz with gain >13 dBic. Then the array is expanded to achieve higher gains. A 16×16-element array is designed, fabricated, and tested. Test results show that the 16×16 array has an AR bandwidth of 13.8% from 18.5 GHz to 21.25 GHz and a peak gain of 25.9 dBic at 20.5 GHz.