Open AccessMode diversity of weakly modulated cavity antennas
Author(s) -
Daniel L. Marks,
David R. Smith
Publication year - 2017
Publication title -
journal of the optical society of america. a, optics, image science, and vision./journal of the optical society of america. a, online
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.803
H-Index - 158
eISSN - 1520-8532
pISSN - 1084-7529
DOI - 10.1364/josaa.35.000135
Subject(s) - physics , terahertz radiation , optics , millimeter , perturbation (astronomy) , mode (computer interface) , effective radiated power , antenna (radio) , electromagnetic field , optoelectronics , radiation , telecommunications , computer science , quantum mechanics , operating system
The radiating mode of a cavity antenna at a particular frequency is fixed. However, by actively modulating the permittivity inside the cavity, the radiating mode may be changed. Using time-independent perturbation theory, we derive the modes of a cavity perturbed by many modulating elements. It is found that with a sufficient number of modulators of sufficient strength, the number of unique fields radiated by the cavity may reach a limit determined by the number of unperturbed cavity modes. The number of addressable radiated fields increases exponentially with the number of modulators; however, perturbations involving the interaction of several modulators become progressively weaker. For antennas at millimeter and terahertz frequencies, such cavity antennas can realize a great diversity of radiation patterns using fewer active devices, better exploiting the diversity achieved by each added modulator.