Effect of superstrate thickness on the performance of broadband circularly polarised stacked patch antenna

Electrically thin superstrates have certain effects on the performance of singly fed CP stacked patch antennas. The thicknesses in the range of 0.0127 to 0.026 λ_o can be regarded as the good choices for an X-band CP-EMCP element. The effect of superstrate thickness on the P-plane mutual coupling is more obvious than the C-plane. In the frequency domain, the concave mutual coupling curve of the CP-EMCP elements explains the unexpected behaviour of the nonmonotonic decay in the spatial domain. Moreover, when designing an array using CP elements, an additional bandwidth in which mutual coupling stays at a specific level should also be considered.