Suspended resonators for filters-reduced λg excitation of evanescent cavities using high dielectric constant feedlines

Richard V. Snyder, Edip Niver, Keehong Um, Sanghoon Shin

Research output: Contribution to journalConference articlepeer-review

1 Scopus citations


A structure consisting of dielectric-loaded feed lines (such as surface wave lines similar to Goubau lines) and below-cutoff air-filled cavities can be used to form essentially L-C sections. The capacitance is due to electric field coupling from the feed line dielectric medium into the below-cutoff section. The inductance results from combining the inductors in the inductive tee-equivalent circuit for such below-cutoff sections. Dielectric loading is used to shorten the guide wavelength at the input to the evanescent section, increasing the effective input inductance. The dielectrically-loaded feed lines can comprise microstrip, CPW, CPS, Goubau lines (surface wave structures), waveguide, etc. The resulting resonant elements are usable at frequencies below 1 GHz, with small dimensions. If connected to the common ground plane, these L-C sections act as a transmission zero. If "floated", i.e. connected in the "hot" line rather than to the ground plane, the sections form bandpass circuits (transmission poles). The air-filled below-cutoff sections (evanescent mode) are placed in a supporting low-dielectric constant medium (air, Teflon or similar), with the open end in proximity to the dielectric portion of the feed line, and are thus termed "suspended". The individual L-C sections can be coupled together using microstrip, surface wave line, CPW, CPS, finline, waveguide, etc. Such combinations can be chosen to implement Chebychev, Butterworth, quasi-elliptic, etc. responses. These applications will be covered later.

Original languageEnglish (US)
Pages (from-to)1597-1600
Number of pages4
JournalIEEE MTT-S International Microwave Symposium Digest
StatePublished - 2002
Externally publishedYes
EventIEEE MTT-S International Microwave Symposium Digest - Seattle, WA, United States
Duration: Jun 2 2002Jun 7 2002

All Science Journal Classification (ASJC) codes

  • Radiation
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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