A major drive in modem RF and microwave circuits design is miniaturisation and performance enhancement through new design and fabrication techniques. Left-handed (LH) metamaterials have sparked the interest of RF and microwave engineers due to their unique electromagnetic properties which not only can enhance circuit performance, but also significantly reduce circuit size. The work in this thesis focuses on the one-dimensional (1-D) circuit approach of LH. metamaterials termed LH transmission line (TL) in developing LH nonlinear and tunable circuits. Two important characteristics of LH TLs are phase advance and anomalous dispersion. The propagation of steady-state pulses, termed envelope solitons, has been investigated theoretically and numerically in a LH nonlinear transmission line (NLTL), where pulse broadening due to anomalous dispersion was balanced by pulse compression due to nonlinearity provided by pn varactor diodes. Additionally, under large-signal conditions, a LH NLTL behaves as a broadband frequency multiplier. A LH NLTL tripler was fabricated and measured and direct comparison was made with a conventional NLTL multiplier. Comprehensive results show that short LH NLTLs are more efficient in power conversion than their conventional counterparts, at least at low and moderate power levels.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:496239 |
| Date | January 2008 |
| Creators | Kafaratzis, Andreas |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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