Resonant properties of the Sierpinski‐based fractal resonator and its application on low‐loss miniaturized dual‐mode bandpass filter

In this article, resonant characteristics of novel microstrip resonators based on the Sierpinski carpet fractal geometries are proposed in detail. With increasing the iteration order of the Sierpinski-based fractal resonators, the resonant frequency is decreased but the unloaded quality factor is slightly enhanced. The resonant properties are discussed using the RLC equivalent circuit. Additional, the design guide for bandpass filter using the nth order resonator is also developed. Using these fractal resonators, several dual-mode bandpass filters using different order resonators can be designed and fabricated to verify the advantages of the size and insertion loss reduction. It is also found good agreement between the simulation and measurement is achieved. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 1358–1361, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24321