Three-dimensional profiling of collimated radio-frequency orbital angular momentum beams

Joshua K. Hamilton, Simon J. Berry, Joseph H. Spencer, Christopher R. Lawrence, Francis C. Smith, Timothy D. Drysdale

Research output: Contribution to journalArticlepeer-review


The use of orbital angular momentum (OAM) modes in radio communication is thought to enhance capacity. This work focuses on using the l = +1 mode transmitted from a 180 mm diameter, 8-element circular antenna array. The transmitted OAM beam was collimated by using a spherical mirror and the intensity and phase were investigated. A xyz scanning stage was used to profile the propagating OAM beam in three dimensions, resulting in a detailed investigation into the effects of collimation on the OAM beam. The proposed system was shown to reduce the beam divergence from 36.6° to 1.2°, without affecting the OAM mode purity of the beam for a frequency range of 4–6 GHz. This investigation showed a step towards realising practical control over the divergence of OAM-carrying beams.
Original languageEnglish
Pages (from-to)547-550
Number of pages4
JournalIET Microwaves, Antennas & Propagation
Issue number6
Early online date28 Feb 2020
Publication statusPublished - 20 May 2020


  • optical vortices
  • optical variables measurement
  • antenna arrays
  • laser beams
  • angular momentum
  • optical links
  • optical design techniques
  • dimensional profiling
  • collimated radio-frequency orbital angular momentum beams
  • orbital angular momentum modes
  • radio communication
  • 180 mm diameter
  • 8-element circular antenna array
  • transmitted OAM beam
  • xyz scanning stage
  • propagating OAM beam
  • beam divergence
  • OAM mode purity
  • OAM-carrying beams
  • size 180
  • 0 mm
  • frequency 4
  • 0 GHz to 6
  • 0 GHz


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