Analysis of circularly polarized E-shaped microstrip antenna

Circular polarized response is realized when two orthogonal closely spaced resonant modes are excited in the patch. An E-shaped patch design using unequal lengths rectangular slots to give circular polarized response was reported. In the reported paper, proper analysis on resonant mode excited in the patch that gives circularly polarization is not explained. An extensive analysis explaining the effects of unequal length slots that gives circularly polarized response is presented in the present paper. The rectangular slots realizes tuning of higher order TM02 mode with respect to fundamental TM10 mode. Further, unequal lengths of two slots and feed point location optimizes the surface current contributions in orthogonal directions inside the patch which yields circularly polarized response. Thus, proposed study gives an insight into the functioning of circular polarized antenna that will help in designing similar configuration at other required frequencies.