Reconfigurable radiation pattern of microstrip antenna using shorting post

Shorting post is generally used to control operating frequency or polarization of microstrip antenna, but it can be applied to reconfigure radiation pattern of microstrip antenna if properly located on the antenna. In this paper, the shifting angle of electric field pattern and the backlobe pattern of rectangular microstrip antenna are investigated as parameters of radiation pattern affected by the presence of shorting post. By changing the number and location of shorting posts, it shows that the shifting angle of electric field pattern can be achieved over 2.25°-15.5°. Meanwhile to keep parameter and VSWR at considerable values, location of the feeding point is varied alternately. Furthermore, it is found that the presence of shorting post can be used to reduce and smoothen backlobe pattern of rectangular microstrip antenna. In the current work the backlobe alternation is measured only by qualitative observation.