Compact Planar Ultrawideband Antennas with Continuously Tunable, Independent Band-Notched Filters

Ming Chun Tang, Hao Wang, Tianwei Deng, Richard W. Ziolkowski

Research output: Contribution to journalArticlepeer-review

75 Scopus citations


A compact planar ultrawideband antenna with continuously tunable, independent band notches for cognitive radio applications is presented. The antenna is fabricated using a copper-cladded substrate. A radiating patch with an inverted rectangular T-slot is etched on the top side of the substrate. A straight rectangular strip with a complete gap is embedded into the T-slot. By placing a single varactor diode across this gap, a frequency-agile band-notch function below 5 GHz is realized. On the bottom side of the substrate, a U-shaped parasitic element having an interdigitated-structure is placed beneath the radiating patch. The second narrow band notch is created by inserting a second varactor diode into the gap on one leg of the parasitic element. It has a frequency-agile performance above 5 GHz. The presence of the interdigitated structure suppresses higher order resonant modes and enhances the tunability of the notched bandwidth. Because these antenna structures naturally block dc, a very small number of lumped elements are required. The experimental results, which are in good agreement with their simulated values, demonstrate that both band notches can be independently controlled and the entire frequency-agile fractional bandwidth is as high as 74.5%, demonstrating a very wide notched frequency-agile coverage.

Original languageEnglish (US)
Article number7471453
Pages (from-to)3292-3301
Number of pages10
JournalIEEE Transactions on Antennas and Propagation
Issue number8
StatePublished - Aug 2016


  • Band-notch filters
  • frequency agile
  • frequency tunable
  • planar antennas
  • ultrawideband (UWB) antennas

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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