Behaviour of characteristic modes on patch antennas in multilayered media

A design methodology is described supported by Characteristic Mode Analysis (CMA) to enhance the radiation gain from a patch antenna using multiple dielectric superstrates. Analytic expressions for the radiation field patterns and impedance match are derived for the patch eigenmodes. An equivalent commercial simulation model is used to determine the associated characteristic modes. Eigenmode and CMA behaviour are studied as low cost planar dielectric sheets are stacked above the antenna to affect an increase in the radiated field gain. Numerical results are compared with laboratory measurements made on several prototype dielectric radome antenna configurations and demonstrate an impedance bandwidth of 3.6% and radiated field pattern gain of 11.5dBi for a double layer superstrate antenna.