Compact ultra-wideband microstrip/coplanar waveguide bandpass filter

Neil Thomson, Jia Sheng Hong

Research output: Contribution to journalArticlepeer-review

140 Citations (Scopus)


A novel ultra wideband (UWB) bandpass filter is presented, using a compact coupled microstrip/coplanar waveguide (CPW) structure. The filter comprises of a single CPW quarter-wavelength resonator which is coupled to two microstrip open-circuited stubs on the other side of a common substrate. The two microstrip open-circuited stubs, which are about a quarter-wave-length long at the center frequency, can function as two resonators with associated coupling arrangement to the CPW. This forms a very compact three-pole filter. The proposed filter also exhibits a quasi-elliptic function response, with one finite-frequency transmission zero closer to each side of the passband. Thus, a high selectivity is achieved using a small number of resonators, which leads to low insertion loss and group delay across the passband. The performance is predicated using EM simulations and verified experimentally. The experimental filter shows a fractional bandwidth of 90% at a center frequency of 6.4 GHz, with two observable transmission zeros (attenuation poles) at 1.95 and 10.36 GHz, respectively. Furthermore, it has a very small size only amounting to 0.25 by 0.08 guided wavelength at the center frequency. © 2007 IEEE.

Original languageEnglish
Pages (from-to)184-186
Number of pages3
JournalIEEE Microwave and Wireless Components Letters
Issue number3
Publication statusPublished - Mar 2007


  • Bandpass filters (BPFs)
  • Coplanar waveguide (CPW)
  • Microstrip
  • Ultra wideband (UWB)


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