Low-Q, electrically small, efficient near-field resonant parasitic antennas

Peng Jin, Richard W. Ziolkowski

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


Metamaterial-inspired electrically small Z, stub and canopy antennas are reported. They are near-field, resonant parasitic designs. Different Z and stub antenna configurations and the effect on their Q values are studied. Their behavior led to the canopy antenna design. At the size of ka ∼ 0.046, the canopy antenna is an electric-based antenna with high overall efficiency (over 90%) and low Q-ratio value and whose input resistance is almost completely matched to a 50 Ω source. The resonant frequency, ∼300 MHz, in the UHF band is selected for the designs. The canopy antenna is studied extensively to explore the lowest achievable Q values. Various coupling configurations, canopy shapes, and metal-air ratios are investigated. Circuit models are also introduced to explain the radiation mechanism. Numerical simulation results are analyzed and compared with previously derived Q value limits for electrically small antennas that are based on the standard circuit models of spherical wave multipoles. The Q value of the canopy antenna for the lowest order, single electric resonance is shown to reach a fundamental limit of approximately 1.75 times the Chu value.

Original languageEnglish (US)
Pages (from-to)2548-2563
Number of pages16
JournalIEEE Transactions on Antennas and Propagation
Issue number9
StatePublished - 2009
Externally publishedYes


  • Antenna efficiency
  • Antenna input impedance
  • Antenna theory
  • Artificial materials
  • Electrically small antennas
  • Q factor

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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