Dual-Spiral Microstrip Bandpass Filter with Two Transmission Zeros

A microstrip bandpass filter using a dual-spiral configuration is proposed. Unlike conventional filter topology, this filter is integrated directly within 50Ω microstrip lines. The filter has a simple configuration, and compact size, and is easy to fabricate. Two transmission zeros close to the passband improve the selectivity of the filter. A demonstration filter is designed and examined, and the theoretical and experimental results are presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 45: 331–332, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20814