Asymmetric-circular shaped slotted microstrip antennas for circular polarization and RFID applications

Nasimuddin*, Zhi Ning Chen, Xianming Qing

*Corresponding author for this work

Research output: Contribution to journalArticle

214 Citations (Scopus)


Novel asymmetric-circular shaped slotted microstrip patch antennas with slits are proposed for circularly polarized (CP) radiation and radio frequency identification (RFID) reader applications. A single-feed configuration based asymmetric-circular shaped slotted square microstrip patches are adopted to realize the compact circularly polarized microstrip antennas. The asymmetric-circular shaped slot(s) along the diagonal directions are embedded symmetrically onto a square microstrip patch for CP radiation and small antenna size. The CP radiation can be achieved by slightly asymmetric (unbalanced) patch along the diagonal directions by slot areas. Four symmetric-slits are also embedded symmetrically along the orthogonal directions of the asymmetric-circular shaped slotted patch to further reduce antenna size. The operating frequency of the antenna can be tuned by varying the slit length while keeping the CP radiation unchanged. The measured 3-dB axial-ratio (AR) bandwidth of around 6.0 MHz with 17.0 MHz impedance bandwidth is achieved for the antenna on a RO4003C substrate. The overall antenna size is 0.27λo×0.27λo× 0.0137λo at 900 MHz.

Original languageEnglish
Article number5582249
Pages (from-to)3821-3828
Number of pages8
JournalIEEE Transactions on Antennas and Propagation
Issue number12
Publication statusPublished - Dec 2010
Externally publishedYes


  • Circular polarization (CP)
  • circularly polarized antenna
  • microstrip antenna
  • radio frequency identification (RFID)
  • slotted patch
  • UHF

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