eprintid: 10074068 rev_number: 16 eprint_status: archive userid: 608 dir: disk0/10/07/40/68 datestamp: 2019-05-21 12:36:41 lastmod: 2021-11-08 00:17:13 status_changed: 2019-05-21 12:36:41 type: article metadata_visibility: show creators_name: Nagar, J creators_name: Chaky, RJ creators_name: Pantoja, MF creators_name: McKinley, AF creators_name: Werner, DH title: Optimization of Far-Field Radiation From Impedance-Loaded Nanoloops Accelerated by an Exact Analytical Formulation ispublished: pub divisions: UCL divisions: B04 divisions: C05 divisions: F46 keywords: Antenna theory, Loop antennas, Optimization, Nanotechnology, Submillimeter wave technology. note: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. abstract: Impedance loading is a common technique traditionally used in the RF to enhance the performance of an antenna, but its application in the optical regime is not as rigorously studied. This is mainly due to a lack of exact analytical expressions that can be used to rapidly predict the radiation properties of loaded nanoantennas. This paper will derive a set of useful analytical expressions for the far-field radiation properties of loop antennas loaded with an arbitrary number of lumped impedances that are valid from the RF to optical regimes. The analytical expressions will be validated with full-wave solvers and can be evaluated more than 100x faster. The ability to perform such rapid evaluations enables, for the first time, large-scale single- and multi-objective optimizations. A series of optimizations reveal that electrically small super-directive antennas can be achieved at a variety of far field angles through capacitive loading, paving the way for a pattern reconfigurable antenna. In addition, gains of greater than 3 dB can be achieved for electrically small antennas over a fractional bandwidth of 28%. Finally, it is shown that impedance loading can be used to achieve circularly polarized radiation from a single loop. date: 2019-03 date_type: published publisher: IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC official_url: https://doi.org/10.1109/TAP.2018.2888727 oa_status: green full_text_type: other language: eng primo: open primo_central: open_green article_type_text: Article verified: verified_manual elements_id: 1642481 doi: 10.1109/TAP.2018.2888727 lyricists_name: McKinley, Arnold lyricists_id: AFMCK30 actors_name: McKinley, Arnold actors_id: AFMCK30 actors_role: owner full_text_status: public publication: IEEE Transactions on Antennas and Propagation volume: 67 number: 3 pagerange: 1448-1458 pages: 11 issn: 1558-2221 citation: Nagar, J; Chaky, RJ; Pantoja, MF; McKinley, AF; Werner, DH; (2019) Optimization of Far-Field Radiation From Impedance-Loaded Nanoloops Accelerated by an Exact Analytical Formulation. IEEE Transactions on Antennas and Propagation , 67 (3) pp. 1448-1458. 10.1109/TAP.2018.2888727 <https://doi.org/10.1109/TAP.2018.2888727>. Green open access document_url: https://discovery.ucl.ac.uk/id/eprint/10074068/1/nanoloop_impedanceLoaded_vFinal_clean.pdf