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Wide-band spiral filter using microstrip patches to increase external and internal coupling

Roshanmanesh, S ; Sharif University of Technology

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  1. Type of Document: Article
  2. DOI: 10.1080/02726343.2012.662853
  3. Abstract:
  4. Microwave filters have successfully been miniaturized using spiral resonators. One of the typical problems in wideband microwave filters, such as spiral filters, is the need for very small gaps between resonators to accomplish high external and internal coupling. These gaps cause difficulties in the physical implementation of the filter, especially at high frequencies. To avoid this problem and to enable easy fabrication of the filter, a rectangular microstrip patch was used as a coupling capacitor instead of small gaps between resonators. This technique was used both for external and for internal coupling of the filter. Additionally, this approach has another important benefit; it removes the requirement of the via hole in the structure of quarter-wavelength resonators. Two kinds of spiral filters, using microstrip patches instead of small gaps, were designed and fabricated. The first is the Chebyshev filter, and the other is the quasi-elliptic filter that has nonadjacent coupling. Quasi quarter-wavelength spiral resonators are used, which are small and have the desirable property of not resonating at a frequency twice as high as that of the main resonance. The minimum dimension in the both cases of the Chebyshev and quasi-elliptical filters is 0.5 mm, which is suitable for a number of applications. Measurement results of both filters show very good agreement with the simulation results
  5. Keywords:
  6. Nonadjacent coupling ; Quasi quarter-wavelength resonator ; Quasi-elliptic filter ; Chebyshev ; Chebyshev filter ; Coupling capacitor ; Easy fabrication ; High frequency ; Internal coupling ; Main resonance ; Measurement results ; Microstrip patch ; Quarter-wavelength ; Quarter-wavelength resonators ; Quasi-elliptic filters ; Rectangular microstrip patch ; Small gaps ; Spiral filter ; Spiral resonators ; Via hole ; Wide band filter ; Wide-band ; IIR filters ; Microwave filters ; Resonators ; Microstrip devices
  7. Source: Electromagnetics ; Volume 32, Issue 3 , 2012 , Pages 161-172 ; 02726343 (ISSN)
  8. URL: http://www.tandfonline.com/doi/abs/10.1080/02726343.2012.662853#.Vrc3iJeHi-E