Microstrip Slow-Wave Open-Loop Resonator Filters with Reduced Size and Improved Stopband Characteristics

  • Akkaraekthalin, Prayoot (Department of Electrical Engineering, King Mongkut's Institute of Technology) ;
  • Jantree, Jaruek (Department of Electrical Engineering, King Mongkut's Institute of Technology)
  • Received : 2006.01.12
  • Published : 2006.10.31


This paper presents a new class of microstrip slow-wave open-loop resonator filters with reduced size and improved stopband characteristics. A comprehensive treatment of both ends loaded with triangular and rectangular ends is described, leading to the invention of a microstrip slow-wave open-loop resonator. Two-resonator and four-resonator bandpass filters are designed at the operating frequency of about 2 GHz, and a bandwidth of 60 MHz. The size of the slow-wave open-loop resonator is optimized from the standpoint of the unloaded Q-factor. The filters are not only compact in size due to the slow-wave effect, but also have a wider upper stopband resulting from the dispersion effect. The filter designs of this type are described in details. The experimental results are demonstrated and discussed.


Supported by : NECTEC, NSTDA