Patch antenna design on dielectric height variation with tapered structure

In the fabrication process of integrated microwave devices a multilevel or dielectric height variation commonly appears. The substrate height is varied due to, for example, anisotropic etch of semiconductor substrate. The problem that arises is to evaluate which are the overall effects on the impedance and resonance properties of the patch antenna with ramp structures. By simple electromagnetic assumptions and analysis it is shown that there are practical design guidelines to determine the correct parameters for these kinds of structures. Using the TLM (transmission line model) the equivalent admittance of each step is transferred to the input port The model dictates a need to taper the structure when dielectric height variation occurs. Experimental devices were fabricated to test the model applications and there was a good agreement with calculated values.