A multiple-frequency resonator in microstrip technology

It has been previously demonstrated in optical fiber that superimposed chirped gratings can be used to implement multi-frequency transmission filters. In this paper, we propose an equivalent electrical implementation of this structure for use in microstrip technology. In an analogous fashion to an optical fiber grating, we modulate the strip-width of a 50-ohm microstrip according to the sum of two linearly chirped sinusoids (known as a “chirped Moiré” structure). By changing the length and center frequencies of these sinusoids, we demonstrate that the number and position of the transmission peaks can be selected.