Zeroth-order Resonant Antenna Research Articles

Investigation of Microwave Negative Refractive Index (NRI) Transmission Lines Incorporating Tunnel Diodes

We investigate microwave active metamaterial transmission lines incorporating gain devices to provide effective negative resistance. Our simulation and experimental results show that by inserting semiconductor tunnel diode at the unit-cell level, the negative phase constant of this kind of transmission line is maintained (i.e., left-handedness kept) while gain can be obtained (negative attenuation constant of transmission line) simultaneously. Important design aspects of the active metamaterial transmission lines are discussed. As a potential application, the performances of passive and active versions of a single unit-cell zeroth-order resonator antenna based on composite right-handed/left-handed transmission line (CRLH-TL) is also compared.

Zeroth-Order Resonator Antennas Using Inductor-Loaded and Capacitor-Loaded CPWs

Two compact zeroth-order resonator (ZOR) antennas designed with inductor-loaded (IL) and capacitor-loaded (CL) coplanar waveguides (CPWs) are proposed. A generalized definition of the zeroth-order resonance is also presented, taking into account the losses of the host transmission lines. Analytic formulas are also derived to predict the reactance values needed to sustain a specified zeroth-order resonant frequency in a lossy host line. With these formulas, one may predict the input reflection coefficients for the proposed ZOR antennas. These antennas, using only two unit cells, are designed, fabricated, and tested, and they have a very compact size and a via-free uniplanar structure. The measured results agree very well with those acquired from the proposed method and full-wave simulations, thus verifying the accuracy of the proposed formulation. It is also demonstrated that the ZOR antenna using the CL CPW exhibits higher radiation efficiency.

Compact epsilon negative zeroth‐order resonator antenna with higher radiation efficiency

AbstractA novel zeroth‐order resonator (ZOR) antenna is presented, which comprises one unit cell of epsilon negative (ENG) structure.Its Q‐factor is decreased by introducing a series capacitor to the shunt branch of the unit cell and reducing the shunt capacitive effect of the ENG structure as well, thus higher radiation efficiency is obtained with very small size of only 9.8 mm × 14.75 mm (0.058λ0 × 0.087λ0 at 1.78 GHz). A prototype is fabricated and measured, and the experimental results show that the novel ZOR antenna can achieve a bandwidth of 25 MHz, monopole‐like radiation pattern, gain of 1.30 dBi, and efficiency up to 78%. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:897–900, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25857

Compact Coplanar Waveguide (CPW)-Fed Zeroth-Order Resonant Antennas With Extended Bandwidth and High Efficiency on Vialess Single Layer

This paper presents the design and analysis of compact coplanar waveguide (CPW)-fed zeroth-order resonant (ZOR) antennas. They are designed on a CPW single layer where vias are not required. The ZOR phenomenon is employed to reduce the antenna size. The novel composite right/left-handed (CRLH) unit cell on a vialess single layer simplifies the fabrication process. In addition, the CPW geometry provides high design freedom, so that bandwidth-extended ZOR antennas can be designed. The antenna's bandwidth is characterized by the circuit parameters. Based on the proposed bandwidth extension technique, symmetric, asymmetric, and chip-loaded antennas are designed. The ZOR characteristic and bandwidth extension are verified by a commercial EM simulator. Their performances are compared with those of previously reported metamaterial resonant antennas. They provide further size reduction, higher efficiency, easier manufacturing, and extended bandwidth.

Co-Planar Waveguide(CPW) 급전 영차 공진 안테나의 방사효율 개선

Abstract In this paper, a co-planar waveguide(CPW)-fed zeroth-order resonant(ZOR) antenna with an improved radiation efficiency was built and tested. The unit cell of the proposed antenna consists of a series metal-insulator-metal(MIM) capacitor and a shorted shunt stub inductor. In order to reduce the antenna size and to achieve the high radiation efficiency two shorted shunt stub arms bent by 90 degree were connected to the ground plane through the via. The proposed antenna consisting of two unit cells has an open ended composite right/left-handed(CRLH) transmission line structure. As a result the dominantly radiating parts of the antenna comes from shunt stub arms and vertical vias. The total size of the fabricated zeroth-order resonant antenna is 0.22   ×0.22   . The measured gain and efficiency of the fabricated antenna have been enhanced by 3.07 dBi and 75 %, respectively, at the zeroth-order resonant frequency of 2.97 GHz.Key words : ZOR(Zeroth-Order Resonant) Antenna, CPW(Co-Planar Waveguide), MIM(Metal-Insulator-Metal), An-tenna Efficiency

Modelling and design of resonant one-dimensional metamaterial-based transmission lines for antenna applications

Various methods of extracting circuit parameters related to radiation effects and closed-form design equations based on them are provided for a one-dimensional (1D) resonant right-/left-handed transmission line (RLH-TL) with open and short terminations. The radiation properties of the RLH-TL have been characterised by simple parameters such as series resistance and shunt conductance in a unit cell using transmission line theory. In order to demonstrate the effectiveness of the modelling and to validate the design equations, two types of zeroth-order antennas based on low- and high-radiation structures have been designed, fabricated and measured. The low-radiation zeroth-order resonant (ZOR) antenna structure at 2 GHz is shown to have a very compact size (0.05λ 0 ×0.1λ 0 ×0.01λ 0 ) with a limited bandwidth, whereas the high-radiation ZOR antenna structure at 10 GHz is shown to have a much wider bandwidth of about 25 , as compared with any reported ZOR antennas in currently available research publications. The modelling of the 1D resonant RLH-TL, in consideration of the radiation effects, considerably narrowed the gap between the RLH-TL characteristics based on circuit simulations and those based on electromagnetic simulations and measurements.

Compact zeroth-order resonance antenna for implantable biomedical service applications

An implantable zeroth-order resonance (ZOR) antenna is proposed. By using chip inductors, an epsilon negative ZOR was generated, while achieving an extremely compact antenna size. The antenna has the overall dimensions of 0.021λ0×0.017λ0×0.002λ0 at the Medical Implantable Communication Service (MICS) band (402–405 MHz) and the 10 dB return loss bandwidth is 2.2% ranging from 400 to 409 MHz. Furthermore, the performance of the proposed antenna is insensitive to the electrical properties of the human body by virtue of the ZOR phenomenon.

Miniaturisation of ε-negative transmission line based zeroth-order resonator antenna

A previously presented epsis-negative transmission line-based zeroth-order resonator antenna structure rescaled to operate at the 2.45 GHz ISM band. The antenna structure is investigated and its feeding network is minimised by using a properly located coaxial. Additionally, a design parameter capable of influencing the radiation pattern is explored. Moreover, this parameter can also reduce the size of the structure. The final antenna structure appears to be better or at least competitive to the best metamaterial-based antennas in terms of size-bandwidth performance.

Wrist-wearable zeroth-order resonant antenna for wireless body area network applications

Proposed is a zeroth-order resonant antenna placed on a wrist for wireless body area network (WBAN) applications. The proposed antenna is insensitive to human body effects and its curvature shape, owing to a bottom ground plate and zero phase constant features. The antenna's performance is simulated and measured through body equivalent liquid and the human body. The radiation patterns and reflection coefficient are constant when the antenna is placed on the body equivalent liquid and the wrist.

A Compact Planar Negative Permittivity ZOR Antenna

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 Compact Zeroth-Order Resonant Antenna Employing Novel Composite Right/Left-Handed Transmission-Line Unit-Cells Structure

This letter presents a compact zeroth-order resonance (ZOR) antenna based on a new type of composite right/left-handed (CRLH) transmission-line unit-cells structure. It has a coplanar waveguide (CPW)-fed input port with modified common ground plane. The unit cell of the proposed antenna consists of a series metal-insulator-metal (MIM) parallel-plate capacitor and a shunt stub inductor shorted by a via-hole. In order to improve its efficiency and to reduce the zeroth-order resonant frequency of the antenna, two straight metal-strip lines and asymmetrical unit cell structures were used for the shunt inductors instead of meander lines. As a result, the total electrical size of the fabricated ZOR antenna employing two unit cells was 0.20 λ0×0.14λ0. The measured gain and efficiency of the fabricated antenna have been improved to 2.3 dBi and 79%, respectively, at the zeroth-order resonant frequency of 2.3 GHz.

Bandwidth enhancement of epsilon negative zeroth‐order resonator antennas using a Co2Y hexagonal ferrite helical loading

AbstractA method to extend the bandwidth of epsilon negative (ENG) zeroth‐order resonator (ZOR) antennas using a Co2Y hexagonal ferrite (Ba2Co1Zn0.7Cu0.3Fe12O22) is presented.It is accomplished by using the ferrite helical loading for shunt inductance of ENG ZOR unit cell. The Co2Y hexagonal ferrite has been developed for performance improvement of mobile handset antennas. The permittivity of the developed Co2Y hexagonal ferrite is about 9.3, and the permeability is about 4. An ENG ZOR antenna based on simplified planar mushroom structure unit cell was fabricated, and bandwidth enhancement and good radiation performance were achieved. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:87–90, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25650

메타 물질을 이용하여 소형화와 주파수 가변이 가능한 영차 공진 안테나

In this paper, a frequency tunable zeroth-order resonant(ZOR) antenna has been implemented. The ZOR characteristics of the proposed antenna is realized by using a composite right-and left-handed(CRLH) transmission line which consists of a rectangular slot on the ground plane of a mushroom structured antenna in order to minimize the antenna size. In addition, the tunable devices are introduced on the slotted ground plane for frequency tuning capability. Depending on the on and off states of the tunable device on the slotted ground plane, a shunt inductance value of the CRLH transmission line is changed and its resonant frequency becomes tunable. From the experimental results, the resonant frequency of the proposed antenna is changed from 4.92 GHz to 2.96 GHz. Additionally, the proposed antenna`s size is reduced by 94.24 % compared with the half-wavelength patch antenna.

A Compact Zeroth-Order Resonant Antenna on Vialess CPW Single Layer

In this letter, a novel zeroth-order resonant (ZOR) antenna on vialess co-planar waveguide (CPW) is proposed. It is based on a composite right/left-handed CPW transmission line. To achieve a compact size, this antenna utilizes the ZOR condition, and its reactive parameters determine the resonant frequency. Each unit cell is composed of a metallic top patch and meander lines. Since it is realized on the CPW single layer, the proposed antenna has the benefits of being a compact size and easy to fabricate. The bandwidth of 6.8% and efficiency of 62% are experimentally achieved. Its bandwidth is enhanced compared with other ZOR antennas.

직각 링과 용량성 결합된 마이크로스트립 패치 구조의 새로운 2차원 메타 재질 구조 CRLH 0차 공진 안테나의 설계

본 논문에서는 Metamaterial CRLH 구조 기반의 0차 공진현상이 발생되는 새로운 직각 패치 안테나가 제안된다. 일반 마이크로스트립 패치 구조의 기본 공진 모드인 반파장 공진이나 반파장 공진의 양의 정수배가 아닌 구조 전체에 전계가 같은 위상을 갖게 하면서, 기존에 발표된 다수의 금속 쎌들이 일렬 연결된 1차원 0차 공진 안테나의 구조와 달리 금속 패치 주위에 하나의 용량성 결합 직각 링만을 부착하는 구조를 제안하는 것이다. 2.4 GHz에서 0차 공진 특성을 갖도록 설계된 등가회로에 따른 물리 구조의 치수들이 입력된 3차원 전자장 분석기에서 안테나의 성능에 대한 모의시험을 수행한다. 설계 결과 2.4 GHz에서 공진점을, 그리고 이득과 효율은 각각 5 dB와 98%를 얻었다. 또한 본 논문이 제안하는 안테나가 마이크로스트립 패치 안테나의 장점인 low-profile과 모노폴 안테나의 장점인 전방향 패턴을 동시에 가지는 특징이 논의된다. In this paper, a novel rectangular patch antenna is proposed to have Zeroth Order Resonance(ZOR) generated based on the Metamaterial Complosite Right- and Left-Handed(CRLH) structure. Making the in-phase electric field over the entire antenna other than a half-wavelength as the fundamental resonance mode of a standard microstrip patch or its positive multiple, the metallic patch is suggested to be capacitively coupled with only one surrounding rectangular ring, different from the previous 1D ZOR antennas commonly having several metal cells in line. The performance of the proposed antenna is simulated by a 3D field solver that inputs the sizes of the physical structure corresponding to the equivalent circuit designed to have ZOR at 2.4 GHz. Consequently, the resonance frequency, the gain and the antenna efficiency are observed 2.4 GHz, 5 dB and 98%, respectively. Besides, the important property of the proposed antenna is addressed as the combination of the low profile as an advantage of microstrip patch antennas, and the omni-directional field pattern typical of monopole antennas.

Effect of Substrate Dimensions on Zeroth-Order Resonator Antennas

This letter focuses on the design of electrically small transmission line zeroth-order resonator antennas (ZORAs). These antennas represent a known concept. However, previous works seem to neglect the size of the substrate. A small antenna that requires a large ground plane loses its competitive advantage. Thus, this letter studies the relation between substrate dimensions and the antenna properties on the example of a ZORA using e-negative transmission line (ENG TL). It was found out that antenna radiation properties deteriorate as the substrate is reduced. Thus, a simple measure based on use of metallic walls to overcome this issue is also introduced in this letter.

Flexible zeroth-order resonant antenna independent of substrate deformation

A novel flexible zeroth-order resonant (ZOR) antenna is proposed. Its zero phase constant ensures that the antenna performance is independent of substrate deformation. A composite right/left-handed transmission line is designed based on coplanar waveguide technology to realise the zeroth-order resonance phenomenon. This provides good performance: reasonable bandwidth (6.5%) and peak gain (0.69–1.39 dBi). Simulated and measured results show that the antenna's resonant frequencies and radiation patterns are almost unchanged at different curvature diameters of 30, 50, 70 mm, as well as for a flat surface. It is belived that this is the first reported ZOR antenna on a flexible substrate.

Electrically Small MNG ZOR Antenna With Multilayered Conductor

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%.

A MICROSTRIP SMALL-SIZED ARRAY ANTENNA BASED ON THE META-MATERIAL ZEROTH-ORDER RESONATOR

A novel microstrip array antenna based on the meta- material zeroth-order resonator (ZOR) is presented in this paper. Considering both zeroth-order resonance and the array theory, a resonant array antenna has been designed and fabricated which has small dimensions both in length and width as well as an acceptable gain. Since the resonant frequency of the zeroth-order resonator is independent of the physical length of the resonator and determined only by LC values loaded in the resonator, therefore, antenna size can be reduced arbitrarily with no changes in the operation frequency and due to the array structure antenna gain can be enhanced. Additional beneflt of the ZOR antennas is lower ohmic losses as compared to the other small antennas and hence the e-ciency of the antenna is higher. The discrepancy between simulation and measurement determined by fabricating some of the simulated design and comparison between the results, has been taken into account for designing the flnal array. A small-sized two-elements ZOR array antenna with 50% reduction in size as compared to the conventional array with a acceptable gain and broad radiation pattern is tested at 4.25GHz. The proposed antenna has application in radio altimeters. The commercial softwares such as CST and HFSS were utilized for design and analysis of the structure.

A Slot-Loaded Composite Right/Left-Handed Transmission Line for a Zeroth-Order Resonant Antenna With Improved Efficiency

In this paper, a new composite right/left-handed transmission line (CRLH-TL) with equilateral slots is proposed for efficiency-improved zeroth-order resonant antennas. A 1-D infinitesimal equivalent transmission line circuit model is derived, and the characteristic impedance and dispersive relation are theoretically computed. Based on the isotropic arranged unit cells of the slot-loaded composite right/left-handed transmission line (SL CRLH-TL), 2-D zeroth-order resonators are designed for planar magnetic monopole antenna applications. The SL CRLH-TL provides the zeroth-order resonance with some degradation of the quality factor. Therefore, a highly efficient radiating resonator can be designed with higher gain at the zeroth-order frequency. The theoretical approach was verified by the experimental results. The radiation efficiency was improved by up to 45.6% for the nine-rectangular zeroth-order resonant antenna and 21.4% for the seven-hexagonal zeroth-order resonant antenna without degrading the radiating performance. Moreover, the antenna gains of these two antennas were enhanced by 7.56 and 6.31 dB, respectively, due to the increase of the radiation efficiency.