Simultaneously fixed/tunable multi-band modulated-width transmission line with varactor loading

G. N. Milford*, Ladislau Matekovits

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

1 Citation (Scopus)


A novel type of reconfigurable microstrip circuit is presented. Because of the periodic modulation of the basic geometry, electromagnetic band-gaps are present in the frequency response of the circuit as verified by numerical and experimental data. Insertion of active elements (varactors) allows modification of the position of the first two band-gaps. Equivalent circuit modeling of the varactor diodes in conjunction with a mixed full-wave/circuit simulation is used to characterise the effects of the varactor bias voltage tuning. The dispersion characteristics are deduced from scattering parameters obtained from the circuit model. The relatively simple bias network in this design makes implementation simple and low cost. In the example presented here, a fixed low-pass response extends from DC to 4.3 GHz, with tunable band-pass responses from 5.7/1.3 to 10.0/2.9 (center frequency/bandwidth, GHz) for bias voltages from 1 to 10 V. Multiple higher pass-band responses are also observed.

Original languageEnglish
Title of host publicationProceedings of the Asia-Pacific Microwave Conference 2011 (APMC)
Place of PublicationPiscataway, NJ
PublisherInstitute of Electrical and Electronics Engineers (IEEE)
Number of pages4
ISBN (Electronic)9780858259744
Publication statusPublished - 2011
Externally publishedYes
EventAsia-Pacific Microwave Conference, APMC 2011 - Melbourne, VIC, Australia
Duration: 5 Dec 20118 Dec 2011


OtherAsia-Pacific Microwave Conference, APMC 2011
CityMelbourne, VIC


  • Active circuits
  • Dispersion
  • Microstrip
  • Periodic structure
  • Tunable circuits and devices


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