Augmenting a modified egyptian axe dipole antenna with non-foster elements to enlarge its directivity bandwidth

Ming Chun Tang, Ning Zhu, Richard W. Ziolkowski

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


Non-Foster elements are introduced to augment an Egyptian axe dipole (EAD) antenna-based system in order to expand its directivity bandwidth. The frequency-agile properties of the original antenna system are investigated near 300 MHz by linearly and discretely changing the values of its internal reactive element. The curve-fit reactance versus frequency curve is established. It is reproduced approximately by augmenting the antenna system with two non-Foster elements implemented internally in one of its near-field parasitic elements and with negative impedance convertor (NIC) designs. It is demonstrated that the resulting electrically small antenna system is capable of achieving excellent unidirectional radiation performance, including a broadside directivity in the range from 5.78 to 6.24 dB with more than a 20 dB front-to-back ratio (FTBR) over a 13% instantaneous fractional bandwidth. The corresponding half-power beamwidths in the E-and H-planes, respectively, are 78° and 138° the radiation efficiency exceeds 65%.

Original languageEnglish (US)
Article number6484100
Pages (from-to)421-424
Number of pages4
JournalIEEE Antennas and Wireless Propagation Letters
StatePublished - 2013


  • Directivity
  • electrically small antennas (ESAs)
  • front-to-back ratio (FTBR)
  • negative impedance converter (NIC)
  • non-Foster element
  • parasitic element

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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