Design of circularly polarized irregular octagonal-shaped and dumbbell slotted planar and conformal patch antennas.

High gains with highly efficient Circularly Polarized (CP) microstrip planar and conformal cylindrical patch antennas are designed for the Industrial Scientific Medical (ISM) band. A dumbbell-shaped slot is incorporated in the centre of an irregular hexagonal radiator to produce circular polarisation with high gain. The simulation results yielded the impedance mismatch loss (S11) bandwidth of 78.8 MHz and axial ratio bandwidth (AR) of 10.3 MHz for the planar patch. In this study, the values of the impedance mismatch loss and AR bandwidths of the conformal cylindrical patch antenna were obtained as 46.2 MHz and 10.6 MHz, respectively, indicating that the return loss bandwidth in this case decreased by almost 42% while the axial ratio bandwidth remained almost the same. The axial ratio of the beam-width for Phi = 0° was 83° and for planar patch and conformal patch, it was 61°. Consequently, in the planar patch, the gain was obtained as 8.79 dBic with 96.33% efficiency while in the conformal patch, the gain was measured as 4.16 dBic with 95% efficiency. [ABSTRACT FROM AUTHOR]