Study Of Microwave Antenna Based On Metamaterials

In order to satisfy the requirements of rapid development of social communicationsystem nowadays, Antenna design with miniaturization, high-gain, multi-band,shared-aperture, wide-band, wide-beamwidth and high-isolation are preferable.However, existing design could not be able to meet the requirement of moderncommunication. Metamaterials open a new way in antenna design. Many issues intraditional antenna design can be well solved by metamaterials, so metamaterials havebeen developed significantly in the past decade. Many antennas with novel structuresand unique features have been proposed.This thesis mainly focuses on the antenna applications based on metamaterials. Itconsists of three parts, including antenna miniaturization based on metamaterial andantennas with multi-band and multi-polarization, metamaterial-based leaky waveantenna and broadband circular polarized antenna loaded with metamaterials.Firstly, the background of metamaterials as well as the development ofmetamaterial-based antennas are introduced. Then the working principle ofmetamaterials is discussed in detail, especially the composite right/left handtransmission line (CRLH TLs), which is the1D form of metamaterials. An efficientmethod of extracting the equivalent circuit parameters is also presented.Secondly, two miniaturized zeroth-order resonant antennas are designed based onCRLH TLs including an epsilon-zero resonance antenna and a mu-zero resonanceantenna. The antenna size can be reduced greatly by this method. What is more, twodual-band antennas based on CRLH TLs are investigated. One is a dual-band EZRantenna, the other is a dua-band dual-polarized EZR/MZR antenna.Due to the exotic dispersion property of the CRLH TLs, combined with itsequivalent cuircuit model analysis, two types of CRLH leaky wave antennascharacterized by singel-side or double-side radiation are proposed and investigated,their backfire-to-endfire beam-steering capabilities through frequency scanning aredemonstrated and discussed in chapter4.At last, a wideband90°phase shifter loaded with one unit cell of the CRLH TL is designed and simulated.On the basis of the wideband phase shifter,a novel widebandcircular-polarized antenna is proposed.Wideband impedance, axial-ratio and gainbandwiths are obtained, and the radiation pattern keeps stable in the widebandfrequency range.