Design And Research Of Novel Planar Antenna Based On Electromagnetic Metamaterial

With the rapid development radio communication system toward integration, multi-function, miniaturization, the antenna will be faced with multiple challenges. The antennas must contain a list of features, such as miniaturized, multi-band, low-profile, wide bandwidth, simple structure, low cost and so on in order to integrated with wireless communication systems. The traditional methods and conventional materials can not meet the needs, the metamaterial has been proposed which open a new direction for the development of antenna. Metamaterial, especially its micro-strip realization lines which be called composite right/left-handed transmission line(CRLH) have been widely applied in antenna designing field. The CRLH has some special characteristics, such as lower loss, wider bandwidth, a nonlinear phase constant and so on.This paper analyzes the research status of metamaterial, describe the basic theory of antenna and metamaterial, mainly focuses on the design of miniaturization and multi-band antenna based on metamaterials. The main contents of this dissertation are as follows:1. A compact triple-band asymmetric coplanar waveguide(ACPW)-fed antenna based on simplified metamaterial transmission lines(SMTL) is designed. The asymmetric coplanar strip feed is analogous to the coplanar wave guide feed which is used for reducing the size of the designed antenna. The antenna consists of two SMTL unit cells of the same dimension, reduced the unnecessary left-hand inductance structure. Three operating bands, which cover UMTS in the 1.76 GHz band, WLAN in the 5.2GHz and 5.8GHz, are achieved when the zeroth-order and first-positive-order modes appear. Surface current distributions and equivalent circuit model are used to analysis the effects of the parameters. Simulated and measured results show that the antenna has good impedance match and stable radiation patterns.2. A wideband miniaturizated antenna based on CRLH-TL is designed. The antenna has a compact dimension of 16×23.2×1.6 mm2. A gap capacitor is inserted into the patch for left-hand series capacitance, and the microstrip stub inductor contributes to the left-handed series inductance. By adjusting the structure of left-hand capacitance and left-hand inductance, a wideband can be achieved when the zeroth-order and first-positive-order modes merge. By etching a slot on the ground plane, better impedance matching can be achieved and causes the antenna to produces a third resonance. Consequently, the antenna can cover the 2.5/3.5-GHz WiMAX and 5.8GHz WLAN bands with a very compact size.3. A multi-band antenna which loaded with composite right/left-handed transmission line structures is designed. By loading two units of CRLH structures on the traditional rectangular patch monopole antenna, two additional resonances can be generated with the original resonance which created by the monopole antenna still remain. By adjusting the dimension of CRLH structure, the resonance frequency can be adjusted flexibly. The antenna can operate on the 2.5-3.69 GHz WiMAX and 1.227 GHz GPS bands. The process of antenna design is introduced and the basic principle of the formation of the bands is analyzed.