Improving the helical antenna performance by changing the pitch angle and the shape of reflector

The modification of the conventional helical antenna by two pitch angles and a truncated cone reflector was analyzed. Limits of the axial radiation mode were examined by criteria defined with axial ratio, HPBW and SLL of the antenna. Gain increase was achieved but the bandwidth of the axial radiation mode remained almost the same. The practical adjustment was made on helical antenna with dielectric cylinder and measured in a laboratory. The measurement results confirmed the improvement of the conventional antenna in terms of gain increase.