Theory and Design of a 3D Antenna with Wideband Radiation Isotropy

Research output: Contribution to journalArticlepeer-review


Internet of Things (IoT) applications require compact antennas with quasi-isotropic radiation patterns to maintain orientation-insensitive communication. Moreover, IoT devices have operational bandwidth requirements and they operate at multiple frequency bands. Therefore, an antenna that can maintain radiation isotropy for a wide bandwidth is promising for IoT applications. In this paper, we present the theory of two orthogonal annular currents with first azimuthal harmonics to obtain wideband quasi-isotropic radiation patterns. Based on the proposed synthesis approach, we determine the optimal phases and magnitude ratios between the currents. This optimized model provides 0.73 dB gain variation at the center frequency and 60% of -7 dB radiation isotropy bandwidth. The sensitivity of the radiation isotropy bandwidth to deviations of the model&#x2019;s parameters is investigated. Inspired by the proposed theoretical model, we also present an antenna design consisting of four dipoles bent around a sphere with an electrical size (<italic>ka</italic>) equal to 1. The fabricated prototype, which is fully printed, demonstrates a measured impedance bandwidth of 70%, a radiation isotropy bandwidth of 33.6%, and an average radiation efficiency of 90.7%. This is the largest reported radiation isotropy bandwidth in the literature.

Original languageEnglish (US)
Pages (from-to)1
Number of pages1
JournalIEEE Transactions on Antennas and Propagation
Issue number1
StateAccepted/In press - 2023

Bibliographical note

Publisher Copyright:


  • Antenna radiation patterns
  • Antenna synthesis theory
  • azimuthal current rings
  • Broadband antennas
  • compact
  • Gain
  • Harmonic analysis
  • Impedance
  • Internet of Things
  • printing
  • quasi-isotropic radiation patterns
  • Wideband
  • wideband antennas

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


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