Metamaterial Superstrate Research Articles

Gain Enhancement of Microstrip Patch Antenna Loaded with Split Ring Resonator Based Relative Permeability Near Zero as Superstrate

In this presented work, Split Ring Resonator (SRR) is arranged in 7X7X4 form to create a metamaterial superstrate which is incorporate on patch antenna. The SRR based metamaterial slab is analysed with Nicolson–Ross–Wier approach to extract the effective parameters of the medium. The Extracted parameters Shows that the relative permeability of the slab is near zero in the vicinity of the resonant frequency of the designed antenna. The experimental results clearly reflect that the gain of the superstrate loaded patch improves by 7.6 dB with variation less than 1 dB in the vicinity of resonant frequency. Structures are simulated on Ansoft HFSS v14 and experimentally verified.

High-Gain and High-Aperture-Efficiency Cavity Resonator Antenna Using Metamaterial Superstrate

In this letter, a high-gain, aperture-efficient cavity resonator antenna using metamaterial superstrate is reported. Highly reflective compact metamaterial surface resonating at 10.15 GHz with measured 3-dB bandwidth stopband characteristic of 4.10 GHz from 8.1 to 12.2 GHz is proposed. Material property of the metasurface is studied by using the free-space technique. Next, the metasurface is used as a superstrate to a patch antenna operating at 10.09 GHz, forming Fabry-Perot cavity. Gain enhancement of 11.85 dB in H-plane and 12.5 dB in E-plane with improved cross-polarization level and front-to-back ratio is observed. The prototype cavity antenna shows calculated gain of 16.35 dB achieving 92.42% of maximum gain due to effective aperture area in H-plane.

Gain enhancement of slot antenna using zero-index metamaterial superstrate

This article presents a technique to enhance the broadside gain of a CPW fed slot antenna using a single layer metamaterial (MTM) superstrate. A finite array of 3 3 ring unit cell has been designed on both sides of a dielectric substrate to form the MTM superstrate. The gain enhancement is obtained using the zero-index property of the metamaterial. The broadside gain enhancement for the proposed antenna is 7.4 dB more in comparison to that of the reference slot antenna. The proposed MTM superstrate loaded antenna provides a minimum overall thickness in the context of using ZIM superstrate for gain enhancement of antennas reported in earlier literatures. The overall thickness of the MTM loaded antenna is 0.13λ0, where λ0 is the free-space wavelength at the resonance frequency of the antenna. Also, a high efficiency of about 93.2% is obtained in this case. The loading of the MTM superstrate produces a minimal effect on the cross polarization performance of the proposed slot antenna.

Programmable omega-based complex medium for beam steering applications

Purpose Metamaterials have been utilised in several exciting configurations such as tuneable reflectors, reconfigurable absorbers, and programmable modulators, triggering intense research efforts. Among them, the ability to steer the radiation pattern of a single antenna component by employing a metamaterial-based superstrate is considered crucial for the development of advanced beam forming applications. The purpose of this paper is to introduce an adjustable omega-inspired metamaterial module to facilitate the design of beam steering implementations, involving beam forming capabilities, as well. Design/methodology/approach A variable capacitive diode is properly positioned at the novel omega element, hence advancing the controllability of its electromagnetic performance and circumventing the requirement of extra bias networks. When an array of these particles is placed in front of an antenna, several negative refractive index profiles can be realised, allowing the manipulation of the beam direction. Furthermore, a pyramidal horn antenna, loaded with this complex medium superstrate, is thoroughly investigated in terms of programmable beam steering and beam forming attributes. Several numerical data derived via the finite element method unveil the merits of the featured configuration. Findings The proposed structure allows programmability of the electromagnetic behaviour, but also circumvents the necessity of complicated bias networks, while minimising interference. The numerical assessment of a standard gain pyramidal horn antenna, associated to the featured metamaterial superstrate, sufficiently proves the controllable beam steering and beam forming attributes. Several parametric studies clarify the principal characteristics of the proposed setup, facilitating the design of high-end systems. Originality/value Development of tuneable metamaterial, which utilises variable capacitive diodes to enable controllability. Incorporation of reconfigurable metamaterials into antenna technology. Design of a pyramidal horn antenna, loaded with a complex medium superstrate exhibiting programmable beam steering and beam forming attributes. The proposed device circumvents the necessity of complicated bias networks, while minimising interference.

Log – Periodic Terahertz Antenna with CSRR Metamaterial Superstrate

Log – Periodic Terahertz Antenna with CSRR Metamaterial Superstrate

Log – Periodic Terahertz Antenna with Square Srr Metamaterial Superstrate

Log – Periodic Terahertz Antenna with Square Srr Metamaterial Superstrate

Analysis and Design of High Gain NRI Superstrate Based Antenna for RF Energy Harvesting System

<p>A high gain patch antenna inspired by 4 layers of negative refractive index (NRI) metamaterial superstrate is proposed to operate at downlink radio frequency (RF) band (935 MHz to 960 MHz of GSM 900). The metamaterial unit cell consists of a nested split ring resonator (SRR) and strip line laminated on other side of FR4 substrate. The effective permittivity and permeability of the proposed unit cell are designed synchronously to approach zero, which leads the NRI superstrate to have impedance match with zero and negative refractive index.The NRI superstrate is studied using Fabry-Perot (F-P) resonant cavity. The gain is improved by 82.48% at the air gap of 55 mm in the desired frequency band.Therefore, the gain of the antenna is effectively enhanced based on the negative refractive index metamaterial. The measured radiation pattern and S parameter results also showed that it has good agreement with the simulation results.</p>

Mutual Coupling Reduction for High-Performance Densely Packed Patch Antenna Arrays on Finite Substrate

This paper reports on an effective mutual coupling suppression technique in which a metamaterial superstrate is placed in between the elements of densely packed microstrip phased array. Modified complementary split ring resonators are printed on the decoupling superstrate slab which caters for both surface and space wave effects. A detailed analysis of this proposed scheme is carried out on a low as well as on a high-permittivity substrate. Coupling suppression of 27 and 11 dB is achieved experimentally on the low- and high-permittivity substrates, respectively, with an element separation of $\lambda_{o}/8$ . The design is compact and easy to realize and it removes drawback of poor front-to-back ratio previously reported in other decoupling techniques. In addition to high-coupling suppression, the decoupling slab can be added or removed in real time which makes this technique versatile for various applications having stringent performance requirements.

Gain enhancement of transmitting antenna incorporated with double-cross-shaped electromagnetic metamaterial for wireless power transmission

This paper proposes a novel approach to enhance the aperture efficiency of the transmitting microstrip patch antenna (MPA) by designing a new inclusion of double-cross-shaped metamaterial (DCSM) superstrate applied in microwave wireless power transmission(WPT). Overall WPT model and transmitting antenna selection are briefly introduced and numerical simulation is conducted in HFSS. Homogenization retrieval method based on transmission and reflection coefficients is utilized to calculate the effective parameters of the DCSM unit cell, electric field and surface current distribution are displayed to qualitatively explain the occurrence of negative permittivity and permeability. The Matlab2008a script is also presented to calculate the geometry dimensions of the corresponding conventional patch antenna operating at desired resonant frequency. Simulation results indicate that the gain of the transmitting antenna increases from 7.46dB to 12.35dB after loading with the 6×3×1 array DCSM MTM as the superstrate, the measured gain increases from 7.1dB to 12.21dB thus an enhancement of 184% for the transmitting antenna's aperture efficiency is obtained which is of significant value for the whole WPT system. For the last section of our paper, electric field of the transmitting MPA before and after loading with DCSM superstrate are illustrated to gain insight physical mechanism of the gain enhancement.

A metamaterial-inspired wideband high-gain FABRY-Perot resonator microstrip patch antenna

In this article, a wide impedance bandwidth and gain bandwidth Fabry–Perot resonator microstrip patch antenna based on metamaterials was presented. The metamaterial superstrate, which is constructed by a doubly periodic array of complementary cross elements, achieved stable reflection phase response within the wide desired operation frequency range to broaden the bandwidth. This antenna worked at 13 GHz, and the simulated and measured impedance bandwidth (S11 < −10 dB) was 1.56 and 1.33 GHz, respectively. The simulated 3 dB gain bandwidth was about 1.1 GHz, and the measured results verified the design. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:1675–1678, 2016

A Negative Refractive Index Metamaterial Structure for Antenna Gain Enhancement

A microstrip patch antenna over which a 6 layer of metamaterial superstrate with the negative refractive index is proposed for the enhancement of gain over the conventional patch antenna The negative refractive index (NRI) property of superstrate covers the frequency range from 774 MHz to 974 MHz. The superstrate is placed 55 mm above the microstrip patch antenna. The function of the properties of negative refractive index is to gather the EM wave radiated from the antenna and the free space toward the normal direction of the antenna. An electromagnetic simulation software CST is used to study the characteristics of this metamaterial and the designe for the proposed antenna. The simulated result indicates that the gain of the proposed antenna is increased by 87.6% (2.32dB), in the desired frequency band 935 MHz to 960 MHz is also increased. Therefore, the gain of the antenna is effectively enhanced based on the negative refractive index metamaterial.

Gain and directivity enhancement of microstrip antenna loaded with multiple splits octagon-shaped metamaterial superstrate

This paper presents a novel multiple splits octagon-shaped metamaterial which exhibits double left-handed frequency bands roughly from 9.25 GHz to 9.68 GHz and from 15.28 GHz to 15.36 GHz derived from the transmission characteristics by homogenization retrieval method. Two conventional microstrip patch antennas whose resonance frequency bands are located at the first left-handed frequency band and the second one respectively are designed to further investigate the influence by loading the proposed metamaterial as its superstrate. HFSS simulation numerical results indicate that the far field radiation directivity half-power bandwidth(HPBW) of the E-plane and H-plane have reduced by 64%, 63.7% and 59.4%, 59%, and the maximal gain increases from 8.251 dB to 11.024 dB and from 8.5432 dB to 11.9653 dB respectively after loading with the multiple splits octagonal metamaterial superstrate.

Design of a broadband and high-gain shared-aperture fabry-perot resonator magneto-electric microstrip antenna

The demands for highly directive antennas are becoming more stringent, especially in microwave regions. Traditional ways to enhance the antenna gain such as reflectors, dielectric lenses, waveguide horns and microstrip antenna arrays suffer design complexity, high cost and power loss in the feeding network, so it is urgent to find a simple way to solve the problem. Fabry-Perot (F-P) antenna has a high directivity and low sidewall, owing to the resonance of the cavity in a cophasal and tapered field distribution along the lateral direction. However, the disadvantage of F-P antenna is obvious for the inherently narrow gain bandwidth which inhibits their many applications. In this paper, a broadband and high-gain shared-aperture F-P resonator magneto-electric (ME) microstrip antenna working at X band is designed and fabricated. In order to design a wideband metamaterial superstrate unit, the structure with two different frequency selective surface (FSS) layers is presented: the metal pattern at the top of the unit is a square patch and has a high reflection coefficient in the high frequency band, and at the bottom the metal pattern is a cross patch, it has a high reflection coefficient in the low frequency band, therefore, the whole unit should resonate in a broadband frequency range. Theoretical analysis and simulation result indicate that the unit has a linearly increasing phase response and a high reflection coefficient across a broadband range and it has the potential to construct a wideband F-P resonator antenna. In the proposed antenna, a novel wideband ME microstrip antenna is used as the feeding source. For the antenna covers the whole X band, the bandwidth of the F-P resonator superstrate should be further expanded. Simulated calculation results indicate that different sizes of two-layer FSSs have different reflection phases but the same coefficient, therefore a shared-aperture structure with three different sizes of FSSs is obtained. The arrangement utilizes the phase compensation property along different FSSs, and broadens the gain enhancement bandwidth effectively. When the superstrate is set to be approximately 15.5 mm above the ground plane of the ME antenna, the antenna possesses an impedance bandwidth of 44.7% for the reflection coefficient (S11) below -10 dB from 7.8 GHz to 12.3 GHz, covering the whole X band. From 7.9 GHz to 12.1 GHz, the antenna has an obvious gain enhancement, with a peak of 7 dB. Numerical and experimental results indicate that compared with the traditional F-P resonator structure, the shared-aperture metamaterial superstrate can effectively broaden the antenna gain enhancement bandwidth, and it has great application values for designing new broadband metamaterial superstrate high-gain antennas.

Gain enhancement with near-zero-index metamaterial superstrate

The objective of this paper was to use a near-zero-index (n) metamaterial as a single- or a double-layer superstrate suspended above a microstrip patch antenna, operating at 43 GHz, for the gain enhancement. The single metamaterial layer superstrate consists of a periodic arrangement of Jerusalem cross unit cells and behaves as an homogeneous medium characterized by a refractive index close to zero. This metamaterial property allows gathering radiated waves from the antenna and collimates them toward the superstrate normal direction. The proposed design improves the antenna gain by 5.1 dB with the single-layer superstrate and 7 dB with the double-layer superstrate.

Investigation on Cylindrical Dielectric Resonator Antenna with Metamaterial Superstrate

The simulation and experimental studies of a probe-fed dual segment cylindrical dielectric resonator antenna with metamaterial superstrate are presented in this paper. The antenna consists of a ceramic material (SrLa2Mg2W2O12) of dielectric constant ?r = 22 and loss tangent tan ? = 0.0021 acting as upper segment and commercially available Teflon having dielectric constant of 2.1 acting as lower segment. The infinity-shaped metamaterial has been used as superstrate. The simulation study has been carried out using Ansys's high frequency structure simulator (HFSS) software. The variation of reflection coefficient with frequency, radiation pattern, and gain of the antenna with and without metamaterial superstrate were simulated and measured in X-band. The antenna bandwidth is increased by 94 % through simulation and 52 % experimentally with the use of metamaterial as a superstrate. The directive radiation pattern with narrow beamwidth is obtained with the use of metamaterial. The use of metamaterial superstrate enhances the peak gain of the antenna by 105 % through simulation and 103 % experimentally.

HYBRID BROADBAND 60-GHZ DOUBLE NEGATIVE METAMATERIAL HIGH GAIN ANTENNA

This paper proposes a double negative metamaterial surface as a superstrate for a multilayer cylindrical dielectric resonator antenna (MCDRA). The aim is to achieve a broadband and high gain Electromagnetic Band Gap (EBG) antenna that can be used in harsh propagation areas to satisfy all the requirements for the 60GHz wireless communications offering a bandwidth of 7GHz in the unlicensed ISM band (57–65 GHz), permitting to reach data rates of 10Gbit/s and more. To meet these objectives various techniques are combined. Numerical and experimental results showed satisfactory performances with achievable impedance bandwidth of more than 10.5% (from 58.1 to 64.2GHz) and a 18 dBi gain, an enhancement of 13 dBi compared to a homogenous DRA without metamaterial superstrate. The proposed antenna exhibits directive and stable radiation pattern in the entire operating band.

High Gain Resonant Cavity Antenna with Meta-material Inspired Superstrate

Abstract A high gain planar Resonant Cavity Antenna (RCA) inspired by metamaterial superstrate is proposed operating at C-band. The RCA is modelled using simple ray tracing method. The unit cell metamaterial consists of Artificial Magnetic Conductor (AMC) and square patch laminated on either side of magneto-dielectric material, is used as the superstrate to design RCA. Square patch is capacitive type and that AMC as inductive. Effects of the reflection phase of the substrate decides the gain of the antenna. A cylindrical dielectric resonator antenna (CDRA) has been used as the primary radiator. The metamaterial unit cell structure is characterized and its effective material parameters are extracted through its S-parameters simulation. The proposed antenna achieves 12.5dBi gain with only 2x2 array superstrate.The results of upto 12 x 12 array superstrate with multiple layers can be demonstrated for higher gain over wide frequency range.

A novel circularly polarized patch antenna with low radar cross section and high-gain

A novel circularly polarized patch antenna, which can achieve low radar cross section (RCS) and high gain performance simultaneously, is designed on the basis of metamaterial superstrate. The novelty of the design is that this antenna can possess the absorbing characteristic and the partially reflective characteristic simultaneously in an integrated structure. The proposed superstrate is composed of two metallic layers with different periodic patterns on both sides of a dielectric substrate. Through constructing different metallic patterns on the two sides of the superstrate, the upper and bottom surfaces of the superstrate will have different transmission and reflection performances when illuminated by an incident plane wave. The low RCS characteristic is dependent on the upper surface, while the gain enhancement of the resonator antenna relies on the reflection coefficient of the bottom surface. The upper surface consisting of a periodic metallic square loop with four lumped resistances on the four sides of the loop is of low reflection and transmission, and the bottom surface composed of a metallic plane with periodic slots is of high reflection and low transmission. When the superstrate is located at approximately half a wavelength above the ground plane of the circularly polarized patch antenna, the upper surface will absorb most of the incident wave by converting the electromagnetic wave into heat as Ohm loss to reduce the antenna RCS, and the bottom surface will form a Fabry-Perot resonance cavity with the ground plane of the antenna to achieve high gain and high directivity by multiple reflections between the bottom surface and the ground plane. The measured results show that with using the superstrate, the relative axial ratio bandwidth of the circularly polarized patch antenna extends from 5.9% to 7.1%, and the high gain performance is achieved in the whole working frequency band, which can be enhanced by 6.61 dB at most. Meanwhile, the RCS of the proposed antenna is dramatically reduced in a wide angle range and a broad frequency band covering a range from 2 to 14 GHz. The measured results are in good agreement with the simulated ones, which further verifies the correctness and effectiveness of the proposed method.

High-gain composite microstrip patch antenna with the near-zero-refractive-index metamaterial

A high-gain rectangular microstrip patch antenna which is covered by a single layer metamaterial (MTM) superstrate with the near zero refractive index is proposed. The refraction of the metamaterial at frequency 3.51GHz–3.57GHz is very close to zero. The metamaterial with the near zero refractive index is placed 42mm above an ordinary rectangular microstrip patch antenna. The effectively zero refractive index behavior of metamaterial superstrate can gather the wave emitted from the microstrip patch antenna and collimate it toward the normal direction of the antenna. The finite element method (FEM) and the finite difference time domain (FDTD) method are used to study the characteristics of this antenna. The results of the two methods indicate that the realized gain of the proposed antenna is increased by more than 6dB, and the antenna has a flatness high gain in the predicted frequency band, where the proposed MTM is designed to have a near zero index of refraction. Therefore, the high-gain antenna is effectively enhanced based on the near-zero-refractive-index metamaterial.

Gain enhancement and broadband using helical resonating metamaterial superstrate in stacked microstrip patch antenna

ABSTRACTMetamaterial superstrate performs unique electromagnetic properties which are used in antenna design. In this article, a novel design of stacked with parasitic element multilayer rectangular microstrip patch antenna using single layer single turn helical resonator based on metamaterial superstrate is presented. The return loss, smith chart, impedance, radiation pattern, gain, VSWR, and directivity of such an antenna are studied. The possibility of increasing bandwidth, gain and directivity of the printed patch antenna using metamaterial superstrate is examined and verified with the realized antenna. The analysis of reduction in the size of helical resonator is given and it is found that maximum reduction in size is obtained at a metallic fill ratio of 0.2. The stacked antenna is realized and successfully tested and verified measured results with the simulated results. Investigation is performed related to gain enhance using metamaterial. Percentage bandwidth of antenna is approximately 64.84% with constant gain in specified bandwidth with good cross‐polarization. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1978–1982, 2014