Generalized modal expansion and reduced modal representation of 3-D electromagnetic fields

Qi I. Dai, Yat Hei Lo, Weng Cho Chew, Yang G. Liu, Li Jun Jiang

Research output: Contribution to journalArticlepeer-review


A generalized modal expansion theory for investigating arbitrary 3-D bounded and unbounded electromagnetic fields is presented. When an inhomogeneity is enclosed with impenetrable boundaries, the field excited by arbitrary sources is expanded with a complete set of eigenmodes, which are classified into trapped modes and radiation modes. As the boundaries tend to infinity, trapped modes remain unchanged, while radiation modes form a continuum. To illustrate the theory, several real-life structures are investigated with a conformal finite-difference technique in the frequency domain. Perfectly matched layers (PMLs) are imposed at finite extent to emulate the unbounded problems. Numerical examples show that, only a few system modes are prominent in expanding an excited field, leading to a reduced modal picture which provides a quick guidance as well as useful physical insight for engineering design and optimization of electromagnetic devices and components.

Original languageEnglish (US)
Article number6671429
Pages (from-to)783-793
Number of pages11
JournalIEEE Transactions on Antennas and Propagation
Issue number2
StatePublished - Feb 2014


  • Generalized modal expansion
  • Microwave antenna design
  • Nano-optics
  • Radiation mode
  • Reduced modal representation
  • Trapped mode

ASJC Scopus subject areas

  • Electrical and Electronic Engineering


Dive into the research topics of 'Generalized modal expansion and reduced modal representation of 3-D electromagnetic fields'. Together they form a unique fingerprint.

Cite this