Multichannel Filters Using Chirped Bandgap Structures in Microstrip Technology

We demonstrate two techniques for creating several narrowband transmission channels within the ultra-wide stopband of a chirped electromagnetic bandgap structure in microstrip technology. In contrast to previous demonstrations which inserted defects into single-frequency-tuned bandgap structures using ground-plane etching, we demonstrate the use of local pi phase-shifts (defects) and "Moire"-type superposition in a sinusoidal chirped bandgap structure having a network topology. We demonstrate the design of 4-to-6-channel filters with lower insertion losses (<5 dB) and broader stopbands than previous approaches in microstrip.