Avoiding conductor width discontinuities at the cell borders in width-modulated microstrip line periodic structures

A planar periodic structure obtained by 2D repetition of a unit cell consisting of a width-modulated microstrip line is considered. The variation of the modulation parameters in different regions of the surface can be exploited to locally control the phase velocity of the surface waves and the surface impedance of the structure. In this context, analysis and solutions are presented aiming to guarantee the continuity of the width of the microstrip lines and simultaneously allowing the widest possible variation of the modulation parameters in subsequent cells.