A High Gain Omnidirectional Antenna Using Negative Permeability Metamaterial

본 논문은 CRLH-TL(composite right left handed transmission line) 메타물질을 이용하여 2.45GHz 무선랜용 ZOR(zeroth order resonance) 안테나를 설계하는 것이다. 일반적으로 안테나는 파장에 대비한 선로의 길이에 따라 공진주파수가 결정되지만 ZOR 안테나는 파장의 길이와 상관없이 안테나의 공진주파수를 결정한다. 그러므로 소형화 할 수 있는 장점이 있으며 방사패턴 또한 등방성의 방사패턴을 가지는 장점이 있다. ZOR 안테나를 설계하기 위해 먼저 단위 셀 길이를 <TEX>${\lambda}/4$</TEX>의 길이보다 작도록 조정하여 균질한 매질 특성을 가질 수 있도록 하였다. 제안된 안테나는 공진 주파수의 감소와 대역폭의 증가를 위하여 CPW 급전을 사용하였고, 기존의 mush-room 형태의 CRLH-TL 보다 높은 인덕턴스와 낮은 캐패시턴스를 얻기 위하여 방사패치와 접지면 사이에 단락 스터브가 사용 되었다. ZOR(zeroth order resonance) antenna for 2.45GHz WLAN(wireless local area network) is designed by use of CRLH-TL(composite right left handed transmission line) meta-material. The electrical length of conventional antennas is determined generally according to the resonant frequency, whereas that of ZOR antenna can be determined without reference to the resonant frequency. Therefore ZOR antenna has advantage in miniaturization of antenna in comparison with conventional antennas. In order to design such ZOR antenna, first unit cell with electrical length shorter than a quarter wavelength at 2.45GHz is designed to the some characteristics of homogeneous medium. In order to decrease resonant frequency and enhance frequency bandwidth, the proposed antenna is fed by CPW(co-planar waveguide) and short stub between radiation patch and ground plane is used for obtaining both higher inductance and smaller capacitance than previous mush-room type of CRLH-TL.

A single layer, low profile, compact metamaterial zeroth-order resonator (ZOR) antenna has been proposed in this paper. A composite right/left-handed (CRLH) transmission line structure that is comprised of a single unit cell makes up the complete antenna. The design complexity of the proposed antenna is very low, since it does not involve any vias. A symmetric coplanar waveguide (CPW) structure is chosen to have design flexibility and to satisfy the design constraints. The main aim of incorporating the left handed behaviour into the design is to achieve compactness. The resonant frequency of zeroth-order mode is around 5.8GHz. A prototype of the proposed antenna has been fabricated and it has the dimensions of 0.348λo × 0.309λo × 0.033λo. The simulated peak gain of the antenna is found to be 0.65dBi. A significant amount of size reduction is observed in the patch area of proposed structure when compared to a regular patch antenna operating at the same frequency. The metamaterial behaviour has been verified with the help of dispersion diagram and vector electric field plot. Simulation is done so as to plot the reflection coefficient of the presented CPW ZOR antenna and it is also observed on the vector network analyzer (VNA). Simulation results show that the proposed ZOR antenna achieves −10dB impedance bandwidth of 7.76% and has a radiation efficiency of about 81.27% at the ZOR mode.

In this paper, multiband dual zeroth order resonator (ZOR) antenna using band-stop filter is proposed for enhanced bandwidth. The ZOR antenna is designed to modified mushroom-like structures having extended ground line on a non-ground region to obtain good efficiency and broad bandwidth. The modified mushroom-like structure is confirmed as double negative (DNG) transmission line by full wave simulated dispersion relation. Moreover, we have presented a bended patch and band-stop filter (BSF) to increase efficiency and bandwidth, respectively. The lengths of each antenna are about λ0/10 at the resonant frequencies of 900MHz and 1800MHz, respectively, and overall dimension of the proposed antenna is 54.4mm (Length) × 4mm (Width) × 5mm (Height). The radiation efficiencies in low and high band are simulated more than 60% and 90%, respectively.

Summary form only given. Wireless medical telemetry service is one of the fastest emerging technologies in healthcare industries worldwide. In addition, the proliferation of smartphones is currently serving as a catalyst to the increasing growth in this sector. Based on a secure, close-range wireless body area network (WBAN) which relays the patient's physiological information to a nearby cellular device, a real-time monitoring system for those who require a relatively close medical attention can be realized. Among the physiological parameters, the pulse and the respiration rates are important indicators for wide range of healthcare applications ranging from recreational sports to wireless medical monitoring. Despite the significant advantages, the technical challenges of devising a wearable, sturdy health monitoring device with a reliable radio must be fully resolved. When operating at the industrial, medical and scientific (ISM) radio band, the antenna is expected to be one of the largest components within the device. It is imperative for the antenna to remain low-profile and yet be capable of exhibiting efficient radiation characteristics albeit the detrimental effects of the user's body on the antenna matching and radiation. In this paper, a planar, zeroth-order resonance (ZOR) antenna is proposed for a wearable and detachable electrocardiography (ECG) sensor device. The profile of the proposed antenna topology is minimized using two distinctive techniques: 1.The elimination of vias unlike the conventional mushroom-shaped ZOR topologies. 2. Modeling of the radiator, series capacitance, shunt inductance and the ground on a single printed circuit board (PCB) layer. An air-bridge employed co-planar waveguide (CPW) structure is designed as the antenna feed network between the antenna element and the in-house low power 2.4 GHz RFIC. The overall dimension of the planar ZOR antenna is 15 mm × 9.6 mm × 3 mm when fabricated using a flexible PCB (İr = 2.2, tan = 0.02). The antenna is placed above the main board PCB of the ECG device and subsequently covered with flexible polycarbonate chassis. The radiation properties of the ZOR antenna within the assembled ECG device is studied by placing the device on the surface of the human body model with electrical properties as follows: Skin (ı=1.46 S/m, h=0.5mm), Body fat (ı=0.27 S/m, h=10.5mm), Muscle (ı=1.74 S/m, h=20mm) where h is denoted as the thickness. Simulation and measurements confirm a -10 dB S11 bandwidth of more than 80 MHz and a radiation efficiency of more than 30% in the presence of the human body. Overall, the ZOR antenna is confirmed to feature more than 3.5 m enhanced communication coverage and more than 20% higher antenna radiation efficiency in comparison to that using conventional chip antennas and monopoles under identical measurement conditions.

A wideband epsilon negative (ENG) zeroth-order resonant antenna designed on a microstrip line is presented. It has a mushroom structure and its size is only 0.040λ0×0.235λ0×0.073λ0 at 9.2 GHz owing to zeroth-order resonance. The design procedures with closed-form solutions are provided using transmission line theory. The measured (simulated) antenna bandwidth is about 20.0% (13.0%) and antenna gain is 7.1 dBi (7.2 dBi), at 9.2 GHz, despite the compact size.

A series of termination circuits for unbalanced composite right/left-handed transmission lines (CRLH TLs) are proposed to enable simultaneous excitation of the zeroth-order series and shunt resonances. The proposed termination circuits are very simple and consist merely of a capacitor or inductor in series/parallel with a parallel/series LC tank. Their operational mechanisms are explained in terms of the equivalent circuit models for CRLH TLs at the two zeroth-order resonances, which can also be used to justify the absence of one of the two zeroth-order resonances in conventional open- or short-ended CRLH TLs. Design formulas to estimate the element values of the termination circuits are derived, and some design considerations are discussed as well. Then, the proposed termination circuits are connected to unbalanced CRLH coplanar waveguides (CPWs) to realize two dual-band compact zeroth-order resonator (ZOR) antennas. Unlike conventional dual- or multi-band ZOR antennas formed by open- or short-ended CRLH TLs, in which only one of the zeroth-order resonances can be excited, our proposed ZOR antennas can operate simultaneously at the zeroth-order series and shunt resonances. It is demonstrated that the proposed antennas have similar input impedance responses, slot-like radiation patterns, and peak gains within the two bands. The antenna size is very compact (of about at the upper resonance) since both designs are formed by only two CRLH CPW unit cells.

In this paper, a compact planar zeroth-order resonator (ZOR) antenna based on epsilon negative (ENG) transmission line is presented. Thanks to the zeroth-order resonance with the aid of virtual ground, we accomplish this proposed antenna with the size of only 0.053λ0 × 0.157λ0 × 0.0096λ0 at 3.580 GHz without destroying the overall substrate. The ZOR characteristic has been analyzed using provided Bloch and Floquet theory. The measured (simulated) bandwidth is about 15 MHz (10 MHz), and the measured (simulated) peak gain is about 2.60 dBi (2.68 dBi), respectively.

A new type of low-profile omnidirectional antenna is proposed in this paper. The proposed antenna has the conceptual configuration of the horizontal magnetic loop current on perfect electric conductor plane, which has been realized by the zeroth-order resonator (ZOR) antenna using mushroom structure. The mushroom structure as a transmission line has negative, zero, and positive propagation constant depending on its operation frequency since mushroom structure is artificial composite right-left handed transmission line. Zeroth-order resonance, of which frequency is independent of physical length, is naturally presented. In particular, mushroom ZOR antenna generates a uniform vertical electric field against ground plane, so that it omnidirectionally radiates in a horizontal plane. Operation frequency, absolute gain, and gain variations for omnidirectional radiation of the designed prototype are 7.9 GHz, 2.6dBi, less than 1.5 dBi, respectively

In this paper, a dual-band open-ended zeroth-order resonant (ZOR) antenna is proposed. This ZOR antenna simply consists of one unit cell of the composite right/left-handed transmission structure and two sections of microstrip lines on both sides. Experimental results show that this open-circuited antenna is able to resonate at 2.37 GHz and 5.68 GHz with infinite-wavelength propagation; moreover, the fractional bandwidths of 0.77% and 2.45% and the peak gains of 1.19 dBi and 2.05 dBi were attained in the lower and higher bands, respectively. The antenna occupies a footprint of 0.122λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> × 0.349λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> , where λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the free-space wavelength at 2.37 GHz.

A novel microdisk resonator sensor based on negative permeability metamaterials. The dispersion relationship of the cyllindrical waveguide coated with single negative metamaterials is obtained, and the resonant frequency and Q factor working at whisper-gallery-mode (WGM) is computed using finite element method (FEM), and agreement between theoretical results and simulation results is demonstrated to be good. Results show that the sensitivity of the sensor is significantly enhanced by the negative permeability metamaterials, and the Q factor can be tailored by adjusting the distance between the waveguide and the microdisk.

In this study, a wideband folded mushroom zeroth-order resonance (ZOR) antenna is presented. To obtain a wide bandwidth, the frequency of the TM010 (λ0/2) mode is down-shifted to the frequency of the ZOR mode by folding a mushroom structure without any additional structure. Thus, the folded mushroom antenna operates over two modes, resulting in a wide bandwidth. The antenna has a dimension of 0.365λ0 × 0.247λ0 × 0.182λ0 at the centre frequency. Its 10 dB fractional bandwidth is measured as 68.3%. The maximum gains of 3.32 and 3.41 dBi are measured at the ZOR mode and the TM010 mode, respectively. Finally, the measured results show good agreements with the simulated results.

Achieving a high‐gain omnidirectional patch antenna with low profile is a challenging task. On the basis of improving antennas by metamaterials, a broadband near‐zero‐index metamaterial (NZIM) is designed to enhance the horizontal gain of the omnidirectional patch antenna. The zero‐index metamaterial is loaded on the substrate of three antennas with different working bands (4.99–5.50 GHz). The results show that the horizontal gain of antennas is enhanced by more than 0.6 dB at various frequencies. The roundness of antennas is also optimised. Therefore, using NZIM can increase the horizontal gain with a low profile ( λ /30) structure size. The low profile, high‐gain omnidirectional patch antenna has great potential in the conformal field.

In this letter, an electrically small mu-negative (MNG) zeroth-order resonance (ZOR) antenna with multilayered conductor is presented. To improve the radiation efficiency, the structure of the MNG ZOR antenna is determined to increase radiation resistance by reducing the current cancellation between the conductor strip of the antenna. In particular, the multilayered conductor is employed to enhance the radiation efficiency by reducing ohmic loss. The MNG ZOR antenna using multilayered conductor (kr = 0.182) has a measured 3-dB fractional bandwidth of 0.846% and radiation efficiency of 18.66%.

In this paper, a single-band omni-directionally circularly polarized Zeroth Order Resonance (ZOR) epsilon negative antenna is proposed. The above proposed antenna is designed for the case where the shunt ZOR is higher than series ZOR. Circular Polarization (CP) is achieved using Asymmetric Unit Cells (AUCs) which create orthogonal components. Zeroth order resonator inherently provides 90° phase shift between two orthogonal polarizations. Left Hand Circular Polarization (LHCP) is achieved by adding stubs with two 90° right bends to the unit cells. Electric field distribution is used to verify the excited resonance for zeroth order and it is found that it follows zeroth order characteristics. The simulated and the measured shunt ZOR are 4.21 GHz and 4.26 GHz, with fractional bandwidths of 1.3 % and 0.87 %, respectively. The simulated and measured LHCP gains are 2.05 dBic and 1.9 dBic, respectively.

This paper presents a novel filter-based analysis for the conventional rectangular patch antenna (RPA) using the Composite Right/Left-Handed Transmission Line (CRLH-TL) theory. We introduce two circuit models for RPA, described by lumped components and transmission line (TL) elements. An RPA is considered a Symmetric CRLH-TL (SCRLH-TL). We validated the analysis by comparing the circuit model and full-wave analysis simulation results. The TL circuit model error in the full-wave analysis was less than 5%. A dual-band Zeroth-Order Resonant (ZOR) antenna is designed and manufactured based on the introduced Lumped element circuit model, which exhibits filtering characteristics in both bands. We obtain the antenna circuit model by incorporating the RPA lump circuit model with LC resonators. We implemented the antenna structure by combining the RPA and complementary split-ring resonators (CSRR) modeled by the LC resonators. We initialized the antenna center frequency bands for WiMAX 2.45 GHz and 3.60 GHz. The CSRRs control the configuration of the center frequencies. The simulation and measured results are in good agreement. The proposed antenna dimensions are 0.66×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}0.66×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}0.012 λg\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\lambda _g$$\\end{document} at 2.45 GHz (43.22×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}43.22×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes$$\\end{document}0.81 mm3). The measured gains are 3.47 dB and 4.64 dB for 2.45 GHz and 3.60 GHz, respectively. Two radiation nulls were observed at 2.09 GHz and 2.98 GHz for the 2.45 GHz band and one radiation null at 3.45 GHz for the 3.60 GHz band. Also, the fractional bandwidth is 4.03% and 1.39%, respectively. The radiation pattern is nearly omnidirectional. The simulated efficiency is 90% for 2.45 GHz and 87% for 3.60 GHz frequency bands.