Three-Dimensional Helical Antenna Array with Circular Polarization.

In this paper, a 4 × 4 planar helical antenna (PHA) array fed by a three-dimensional substrate integrated waveguide (SIW) power splitter is presented. The 4 × 4 array is composed of four 1 × 4 PHA subarrays, and each subarray is fed by the SIW power splitter. Since the helical antenna is end-fire, it could not be integrated into a 4 × 4 array in a 2-D plane. In order to realize a 4 × 4 array, a SIW twist vertical transition structure is designed to connect the subarray with the SIW power splitter. Finally, the proposed 4 × 4 helical antenna array is implemented and fabricated for measurement. The center frequency of the PHA is 11 GHz, the impedance bandwidth (IBW) is 10.16-11.99 GHz (16.64%), and the axial ratio bandwidth (ARBW) is 10.53-11.47 GHz with the peak gain of 18.44 dBi. The simulation and measurement results match each other well; therefore, the effectiveness of the proposed design is verified.