Parametric Study of a Bidirectional Antenna using a Probe Excited Rectangular Ring

The parametric study of a bidirectional antenna using a probe excited rectangular ring by using dyadic Green function approach is presented. The antenna characteristics depend on the probe length, ring width, ring height and ring length. The maximum elevation beam peak in E-plane is tilt a bit from z-axis as the reason of probe position is not symmetry between the upper and lower side of the ring. The radiation pattern in H-plane is inclined a bit, because the probe is not located at the center of the ring. In addition, the antenna was fabricated. The experiments were set up to verify the theoretical predictions. The ring width and ring height are selected based on the dominant mode propagation. The ring length is optimized to achieve the optimum radiation pattern. The antenna produces the linear polarization. Furthermore, it is found that the shorter ring length provide the higher level of cross-polarized field. The experimental results have the same trend with the theoretical predictions. However, the actual current distributions, mutual coupling, reflection at the edge are not taken into consideration; these are left for further study