Using huygens multipole arrays to realize unidirectional needle-like radiation

Richard W. Ziolkowski

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


For nearly a century, the concept of needle radiation has captured the attention of the electromagnetics communities in both physics and engineering, with various types of contributions reoccurring every decade. With the near-term needs for highly directive, electrically small radiators and scatterers for a variety of communications and sensor applications, superdirectivity has again become a topic of interest. While it is well known that superdirective solutions exist and suffer ill-posedness issues in principle, a detailed needle solution has not been reported previously. We demonstrate explicitly, for the first time, how needle radiation can be obtained theoretically from currents driven on an arbitrary spherical surface, and we explain why such a result can only be attained in practice with electrically large spheres. On the other hand, we also demonstrate, more practically, how broadside radiating Huygens source multipoles can be combined into an end-fire array configuration to achieve needle-like radiation performance without suffering the traditional problems that have previously plagued superdirectivity.

Original languageEnglish (US)
Article number031017
JournalPhysical Review X
Issue number3
StatePublished - Jul 26 2017

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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