Showing papers on "Metamaterial antenna published in 2015"
TL;DR: In this paper, a metamaterial-based broadband low-profile grid-slotted patch antenna is presented, where a periodic array of series capacitor-loaded patch cells is formed, and excited through the coupling aperture in a ground plane right underneath and parallel to the slot at the center of the patch.
Abstract: A metamaterial-based broadband low-profile grid-slotted patch antenna is presented. By slotting the radiating patch, a periodic array of series capacitor loaded metamaterial patch cells is formed, and excited through the coupling aperture in a ground plane right underneath and parallel to the slot at the center of the patch. By exciting two adjacent resonant modes simultaneously, broadband impedance matching and consistent radiation are achieved. The dispersion relation of the capacitor-loaded patch cell is applied in the mode analysis. The proposed grid-slotted patch antenna with a low profile of $0.06 \lambda_{0}$ ( $\lambda_{0}$ is the center operating wavelength in free space) achieves a measured bandwidth of 28% for the $\vert{\text{S}_{{11}}}\vert$ less than $-{10}\;\text{dB}$ and maximum gain of 9.8 dBi.
239 citations
TL;DR: In this paper, a metamaterial medium for electromagnetic energy harvesting based on the full absorption concept is proposed, where the power absorption is mostly dissipated across a resistive load instead of the dielectric substrate.
Abstract: We present the design of a metamaterial medium for electromagnetic energy harvesting based on the full absorption concept. A metamaterial slab was designed comprising 13 × 13 electrically small cells, each loaded with an 82 Ω resistor which mimics the input impedance of a rectification circuitry. Unlike earlier designs of metamaterial absorbers, here the power absorption is mostly dissipated across a resistive load instead of the dielectric substrate. This implies that effective electromagnetic energy harvesting can be achieved. The power is channeled through a via connected to each cell. For a design optimized at 3 GHz, simulation and experimental results show power absorption efficiency of 97% and 93%, respectively.
195 citations
TL;DR: In this article, a dynamic metamaterial aperture was proposed for use in computational imaging schemes at microwave frequencies, which consists of an array of complementary, resonant metammaterial elements patterned into the upper conductor of a microstrip line.
Abstract: We present a dynamic metamaterial aperture for use in computational imaging schemes at microwave frequencies. The aperture consists of an array of complementary, resonant metamaterial elements patterned into the upper conductor of a microstrip line. Each metamaterial element contains two diodes connected to an external control circuit such that the resonance of the metamaterial element can be damped by application of a bias voltage. Through applying different voltages to the control circuit, select subsets of the elements can be switched on to create unique radiation patterns that illuminate the scene. Spatial information of an imaging domain can thus be encoded onto this set of radiation patterns, or measurements, which can be processed to reconstruct the targets in the scene using compressive sensing algorithms. We discuss the design and operation of a metamaterial imaging system and demonstrate reconstructed images with a 10:1 compression ratio. Dynamic metamaterial apertures can potentially be of benefit in microwave or millimeter wave systems such as those used in security screening and through-wall imaging. In addition, feature-specific or adaptive imaging can be facilitated through the use of the dynamic aperture.
152 citations
TL;DR: The method provides an effective technique for antenna pattern optimization for a holographic antenna, which significantly suppresses sidelobes and is demonstrated both on a computational model of the antenna and experimentally.
Abstract: Accurate and efficient methods for beam-steering of holographic metamaterial antennas is of critical importance for enabling consumer usage of satellite data capacities. We develop an algorithm capable of optimizing the beam pattern of the holographic antenna through software, reconfigurable controls. Our method provides an effective technique for antenna pattern optimization for a holographic antenna, which significantly suppresses sidelobes. The efficacy of the algorithm is demonstrated both on a computational model of the antenna and experimentally. Due to their exceptional portability, low-power consumption, and lack of moving parts, holographic antennas are an attractive and viable technology when combined with proven software-based strategies to optimize performance.
129 citations
TL;DR: In this article, a stub-loaded microstrip patch antenna with reconfigurable operation in both frequency and polarization is presented, using 12 varactors with two independent voltages, achieving a fractional bandwidth of around 40% while allowing selection between circular polarization with both rotating senses and linear polarization (LP).
Abstract: A stub-loaded microstrip patch antenna with reconfigurability in both frequency and polarization is presented. Using 12 varactors with two independent voltages, reconfigurability is achieved in a fractional bandwidth of around 40% while allowing selection between circular polarization (CP) with both rotating senses and linear polarization (LP). The design is optimized based on an analytical model, which significantly speeds up the process while yielding reasonably accurate predictions. For illustration of the concept, an antenna is designed, optimized, and manufactured for reconfigurable operation in the 2.4–3.6 GHz frequency range. A good agreement between simulations and measurements is obtained which validates the proposed method. A full reconfigurability is demonstrated in the operation band with the ability to both tune the antenna to a given frequency and select a polarization state among left-hand or right-hand CP or various states of LP.
124 citations
TL;DR: In this paper, a dual-band, wearable metamaterial-loaded antenna is proposed for 2.4/5.2 GHz WLAN applications, which features a low backward radiation in both bands.
Abstract: A dual-band, wearable metamaterial-loaded antenna is proposed for 2.4/5.2-GHz WLAN applications. The loading is with a composite right/left-handed transmission line (CRLH-TL) metamaterial, resulting in a significant miniaturization down to ${\lambda _0}/6 \times {\lambda _0}/6 \times {\lambda _0}/20$ . Similar radiation patterns are obtained by simultaneously exciting the first-order positive ( ${ n}=+1$ ) and negative ( ${ n}=-1$ ) modes. The antenna features a low backward radiation in both bands, which is highly desirable in minimizing electromagnetic coupling to the body. The antenna is fabricated fully using textiles except for the connector and is evaluated in free space and on body, under both planar and bent conditions. Besides a good agreement between simulations and measurements, results indicate that the proposed topology is reasonably immune to body coupling and robust with respect to mechanical changes. The specific absorption rate (SAR) level is numerically investigated to determine the on-body safety level.
116 citations
TL;DR: In this paper, a multi-layer periodic array design is proposed for sub-wavelength Fabry-Perot cavity type antennas with enhanced bandwidth performance, achieving 16.9 dBi directivity with 10.7% 3 dB bandwidth.
Abstract: A method for designing sub-wavelength-profile and broadband high-gain planar antennas is presented. A novel multi-layer periodic array design is proposed for sub-wavelength Fabry-Perot cavity type antennas with enhanced bandwidth performance. Three double-sided periodic arrays are designed and optimized, each double-sided array consisting of a capacitive artificial impedance surface (AIS) and an inductive partially reflective surface (PRS) printed on either side of a dielectric substrate. They are placed at about sixth of a wavelength from a ground plane and from each other. Thus, three air cavities are created with a total profile of $\lambda/2$ . The proposed antenna has been simulated using CST Microwave Studio and measured achieving 16.9 dBi directivity with 10.7% 3 dB bandwidth. The gain-bandwidth product of the proposed designs outperforms any previous Fabry-Perot antenna design with this profile.
114 citations
TL;DR: The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.
Abstract: A miniaturized antenna employing a negative index metamaterial with modified split-ring resonator (SRR) and capacitance-loaded strip (CLS) unit cells is presented for Ultra wideband (UWB) microwave imaging applications. Four left-handed (LH) metamaterial (MTM) unit cells are located along one axis of the antenna as the radiating element. Each left-handed metamaterial unit cell combines a modified split-ring resonator (SRR) with a capacitance-loaded strip (CLS) to obtain a design architecture that simultaneously exhibits both negative permittivity and negative permeability, which ensures a stable negative refractive index to improve the antenna performance for microwave imaging. The antenna structure, with dimension of 16 × 21 × 1.6 mm³, is printed on a low dielectric FR4 material with a slotted ground plane and a microstrip feed. The measured reflection coefficient demonstrates that this antenna attains 114.5% bandwidth covering the frequency band of 3.4-12.5 GHz for a voltage standing wave ratio of less than 2 with a maximum gain of 5.16 dBi at 10.15 GHz. There is a stable harmony between the simulated and measured results that indicate improved nearly omni-directional radiation characteristics within the operational frequency band. The stable surface current distribution, negative refractive index characteristic, considerable gain and radiation properties make this proposed negative index metamaterial antenna optimal for UWB microwave imaging applications.
91 citations
TL;DR: In this paper, a broadband elastic metamaterial with single negativity (negative mass density or Young's modulus) is proposed by mimicking lattice systems, which has two stop bands and the bandwidth of the second one is infinite theoretically.
Abstract: The narrow bandwidth is a significant limitation of elastic metamaterials for practical engineering applications In this paper, a broadband elastic metamaterial with single negativity (negative mass density or Young's modulus) is proposed by mimicking lattice systems It has two stop bands and the bandwidth of the second one is infinite theoretically The effect of the relevant parameters on band gaps is discussed A continuum model is proposed and the selection of materials is discussed in detail It shows that continuum metamaterials can be described accurately by using the lattice model, and the second stopband can be ultra-broad but not infinite This discrepancy is investigated and a method is provided to calculate the upper limit of the second stopband for a continuum metamaterial As a verification, the proposed metamaterial is used for wave mitigation over broadband frequency ranges Moreover, the present method is extended to design 2D anisotropic elastic metamaterials, and a device to control the direction of elastic wave transmission is proposed as an example
91 citations
TL;DR: In this paper, an efficient decoupling feeding network is proposed, which is composed of two directional couplers and two sections of transmission line for connection use, which can be used to cancel out the direct coupling caused by space waves and surface waves between array elements.
Abstract: An efficient decoupling feeding network is proposed in this letter. It is composed of two directional couplers and two sections of transmission line for connection use. By connecting the two couplers, an indirect coupling with controlled magnitude and phase is introduced, which can be used to cancel out the direct coupling caused by space waves and surface waves between array elements. To demonstrate the method, a two-element microstrip antenna array with the proposed network has been designed, fabricated and measured. Both simulated and measured results have simultaneously proved that the proposed method presents excellent decoupling performance. The measured mutual coupling can be reduced to below $-58 ~\hbox{dB}$ at center frequency. Meanwhile it has little influence on return loss and radiation patterns. The decoupling mechanism is simple and straightforward which can be easily applied in phased array antennas and MIMO systems.
78 citations
TL;DR: High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors.
Abstract: This paper presents a negative index metamaterial incorporated UWB antenna with an integration of complementary SRR (split-ring resonator) and CLS (capacitive loaded strip) unit cells for microwave imaging sensor applications This metamaterial UWB antenna sensor consists of four unit cells along one axis, where each unit cell incorporates a complementary SRR and CLS pair This integration enables a design layout that allows both a negative value of permittivity and a negative value of permeability simultaneous, resulting in a durable negative index to enhance the antenna sensor performance for microwave imaging sensor applications The proposed MTM antenna sensor was designed and fabricated on an FR4 substrate having a thickness of 16 mm and a dielectric constant of 46 The electrical dimensions of this antenna sensor are 020 λ × 029 λ at a lower frequency of 31 GHz This antenna sensor achieves a 1315% bandwidth (VSWR < 2) covering the frequency bands from 31 GHz to more than 15 GHz with a maximum gain of 657 dBi High fidelity factor and gain, smooth surface-current distribution and nearly omni-directional radiation patterns with low cross-polarization confirm that the proposed negative index UWB antenna is a promising entrant in the field of microwave imaging sensors
TL;DR: In this article, a low radar cross section (RCS) microstrip antenna is proposed and investigated based on implementation of frequency-selective surfaces (FSSs) and microstrip resonators.
Abstract: A low radar cross section (RCS) microstrip antenna is proposed and investigated in this letter. This design is based on implementation of frequency-selective surfaces (FSSs) and microstrip resonators. By using the FSS ground instead of the solid metal ground, out-of-band RCS reduction can be realized. Moreover, in-band RCS reduction can be obtained by loading microstrip resonators. Significant RCS reduction has been accomplished in the frequency ranges of 3-10 GHz. Compared with the reference antenna, the simulation results show that RCS reduction of the proposed antenna in and out of the operation band is as much as 13 and 17 dB, respectively. Measured results satisfactorily agree with the simulated ones. Radiation performance of the proposed antenna is preserved compared with the reference antenna.
TL;DR: In this article, a multiband microstrip antenna with a proximity-coupled feed for operating in the LTE-2300 (2300-2400 MHz), Bluetooth (2400 -2485 MHz), WiMAX (3.3-3.7-GHz), and WLAN (5.15-5.35 GHz, 5.725 -5.825 GHz) bands is presented.
Abstract: This letter presents a new design of a multiband microstrip antenna with a proximity-coupled feed for operating in the LTE2300 (2300–2400 MHz), Bluetooth (2400–2485 MHz), WiMAX (3.3–3.7 GHz), and WLAN (5.15–5.35 GHz, 5.725–5.825 GHz) bands. In addition, it also covers 6-dB impedance bandwidth across the UMTS (1920–2170 MHz) band. The proposed antenna consists of a corner-truncated rectangular patch with a rectangular slot, meandered microstrip feed, and defected ground plane. The antenna is fabricated using 0.8-mm-thick FR4 substrate with a dielectric constant of 4.4 and has a small size of only $27\times 24~\hbox{mm}^{2}$ . The antenna shows a stable gain over the operating bands and good radiation characteristics. The simulated and measured results are shown to have good agreements.
TL;DR: The results provide the basis for the design of new ultrasensitive chemical and biosensors outperforming both surface plasmon polaritons and localised surface plasmons based transducers.
Abstract: Metamaterials with hyperbolic dispersion based on metallic nanorod arrays provide a flexible platform for the design of bio- and chemical sensors and nonlinear devices, allowing the incorporation of functional materials into and onto the plasmonic metamaterial. Here, we have investigated, both analytically and numerically, the dependence of the optical response of these metamaterials on refractive index variations in commonly used experimental sensing configurations, including transmission, reflection, and total internal reflection. The strategy for maximising refractive index sensitivity for different configurations has been considered, taking into account contributions from the superstrate, embedding matrix, and the metal itself. It is shown that the sensitivity to the refractive index variations of the host medium is at least 2 orders of magnitude higher than to the ones originating from the superstrate. It is also shown that the refractive index sensitivity increases for higher-order unbound and leaky modes of the metamaterial sensor. The impact of the transducer’s thickness was also analysed showing significant increase of the sensitivity for the thinner metamaterial layers (down to few 0.01 fraction of wavelength and, thus, requiring less analyte) as long as modes are supported by the structure. In certain configurations, both TE and TM-modes of the metamaterial transducer have comparable sensitivities. The results provide the basis for the design of new ultrasensitive chemical and biosensors outperforming both surface plasmon polaritons and localised surface plasmons based transducers.
TL;DR: In this article, a planar-patterned metamaterial structure was proposed for ultra-wideband applications, which has a wide bandwidth from 3.07 to 19.91 GHz for voltage standing wave ratio (VSWR) <2 and an average gain of 5.62 dBi with a peak of 8.57 dBi.
Abstract: A compact antenna is proposed using planar-patterned metamaterial structures for ultra-wideband applications. This antenna consists of four metamaterial unit cells that simultaneously show both negative permeability and negative permittivity on the triangular patch and three rectangular slots on the partial ground plane fed with a microstrip line. It has a wide bandwidth from 3.07 to 19.91 GHz for voltage standing wave ratio (VSWR) <2 and an average gain of 5.62 dBi with a peak of 8.57 dBi because of using planar-patterned metamaterial structures. Good agreement between computations and experiments is realised convincing that the antenna can operate over a wide bandwidth with planar-patterned metamaterial structures and compact size (0.28λ × 0.19λ × 0.02λ).
TL;DR: In this paper, a planar magneto-electro-dielectric wave-guided metamaterials (MED-WG-MTM) was proposed to manipulate the effective permeability and the effective permittivity.
Abstract: A new concept of planar magneto-electro-dielectric waveguided metamaterials (MED-WG-MTM) is proposed to manipulate the effective permeability ${\mu_{\mathrm {eff}}}$ and the effective permittivity ${\varepsilon_{\mathrm {eff}}}$ . The MED-WG-MTM cell consists of an electric complementary spiral ring resonator (CSR) in the upper metallic plane and a magnetic embedded Hilbert-line (EHL) in the ground plane. The characterizations and working mechanisms are investigated in depth through eletromagnetic (EM) simulation, circuit model calculation and effective material parameters analysis. Numerical results show that the MED-WG-MTM can be manipulated with a larger refractive index for miniaturization and a larger wave impedance for bandwidth (BW) enhancement. For demonstration and potential applications, a microstrip patch antenna working at 3.5 GHz and occupying an area of only ${0.20 \lambda _0 \times 0.20 \lambda _0}$ is designed by using the derived flexible three-step frequency tuning method. A good agreement of results between the simulations and measurements suggests that the designed antenna advances in many aspects such as compact dimensions with a 42.53% miniaturization, broad operation band with a 207% impedance BW enhancement, and comparable radiation performances relative to its conventional counterparts.
TL;DR: In this paper, a novel metamaterial superstrate with S-shaped elements is implemented to improve the gain characteristics of the microstrip patch antenna, a prototype of the designed antenna structure is manufactured and measured.
Abstract: The procedure of gain enhancement for a microstrip patch antenna by employment of metamaterial superstrates and forming Fabry-Perot (FP) antennas is presented and discussed in this paper. In order to improve the gain characteristic of the microstrip patch antenna, a novel metamaterial superstrate with S-shaped elements is implemented. The main advantage of the presented S-shaped elements structure is that, it leads to achieve simultaneous enhancement on antenna gain and bandwidth. The microstrip patch antenna and its reflective surface are designed and modified for ISM-band, which operates at 5.725–5.875 GHz. A prototype of the designed antenna structure is manufactured and measured. The designed and fabricated antenna has a simple structure and does not include undesirable complexity of the recently reported FP antennas. The antenna has a good radiation behavior in the improved desired bandwidth of 5.65–5.935 GHz with more than 0.92% impedance bandwidth and 8 dBi gain improvement at maximum radiation direction.
TL;DR: A methodology for the time-domain characterization and evaluation of graphene-based plasmonic miniaturized antennas is presented, which aims to build a bridge between technological aspects, antenna design, and communications.
Abstract: Graphene is enabling a plethora of applications in a wide range of fields due to its unique electrical, mechanical, and optical properties. Among them, graphene-based plasmonic miniaturized antennas (or shortly named, graphennas ) are garnering growing interest in the field of communications. In light of their reduced size, in the micrometric range, and an expected radiation frequency of a few terahertz, graphennas offer means for the implementation of ultra-short-range wireless communications. Motivated by their high radiation frequency and potentially wideband nature, this paper presents a methodology for the time-domain characterization and evaluation of graphennas. The proposed framework is highly vertical, as it aims to build a bridge between technological aspects, antenna design, and communications. Using this approach, qualitative and quantitative analyses of a particular case of graphenna are carried out as a function of two critical design parameters, namely, chemical potential and carrier mobility. The results are then compared to the performance of equivalent metallic antennas. Finally, the suitability of graphennas for ultra-short-range communications is briefly discussed.
TL;DR: The potential of a hyperbolic medium in the design of an efficient metamaterial antenna enabling detection and tracking of a nonlinear object, with an otherwise hidden second-harmonic signature, is numerically demonstrated.
Abstract: The detection and processing of information carried by evanescent field components are key elements for subwavelength optical microscopy as well as single molecule sensing applications. Here, we numerically demonstrate the potential of a hyperbolic medium in the design of an efficient metamaterial antenna enabling detection and tracking of a nonlinear object, with an otherwise hidden second-harmonic signature. The presence of the antenna provides 103-fold intensity enhancement of the second harmonic generation (SHG) from a nanoparticle through a metamaterial-assisted access to evanescent second-harmonic fields. Alternatively, the observation of SHG from the metamaterial itself can be used to detect and track a nanoparticle without a nonlinear response. The antenna allows an optical resolution of several nanometers in tracking the nanoparticle’s location via observations of the far-field second-harmonic radiation pattern.
TL;DR: Based on the equivalence principle of Huygens surface, this paper proposed a transparent metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics.
Abstract: Metasurface, as a planar version of artificial metamaterial, provide an effective way to manipulate electromagnetic wave propagation. Here, we present a transparent metasurface for compensating the out-of-phase radiation from a microstrip patch antenna to improve its radiation gain and bandwidth. Based on the equivalence principle of Huygens’ surface, we propose metasurface composed of both inductive and capacitive resonant elements which could produce high transmission with variable phase characteristics. Such metasurface mounted on a patch antenna can transform the spherical-like phase profile generated from the patch into an in-phase planar one. A prototype antenna has been fabricated and validated the squeezed radiation pattern with suppressed sidelobes as well as enhanced impedance bandwidth due to strong near-field coupling. As operating at around 5.7 GHz, the proposed antenna may have potential application in wireless communication systems especially for point-to-point data transmission. It is believed that the design methodology could also be scaled to other frequency bands such as millimeter or terahertz wave.
TL;DR: A new approach to control the amplitude and phase distributions of electromagnetic fields over the aperture of a horn antenna is proposed, by loading a metamaterial lens inside the horn antenna, which can suppress the side-lobe radiations of the antenna.
Abstract: We propose a new approach to control the amplitude and phase distributions of electromagnetic fields over the aperture of a horn antenna. By loading a metamaterial lens inside the horn antenna, a tapered amplitude distribution of the aperture field is achieved, which can suppress the side-lobe radiations of the antenna. The metamaterial is further manipulated to achieve a flat phase distribution on the horn aperture to avoid the gain reduction that usually suffers in the conventional low-sidelobe antenna designs. A prototype of the metamaterial-loaded horn antenna is designed and fabricated. Both numerical simulations and measured results demonstrate the tapered aperture-field distribution and significant reduction of side-lobe and back-lobe radiations in the operating frequency band.
TL;DR: In this paper, a dual-band miniaturized planar antennas loaded with 4-cell metamaterials is presented, which consists of a coplanar waveguide at input, microstrip line, patch, metammaterial loaded substrate under patch, and back conductor.
Abstract: New dual band miniaturized planar antennas loaded with 4-cell metamaterial is presented. The structure of the antenna consists of a coplanar waveguide at input, microstrip line, patch, metamaterial loaded substrate under patch, and back conductor. For simpler construction procedure, U-shaped and inverted U-shaped metamaterial loaded substrate under the patch is made in two layers. At the first band, these antennas work as a wideband monopole antenna with about 35% miniaturization compared to the folded monopole antenna, and at the second band as a wideband patch antenna with about 77% miniaturization compared to the conventional patch antenna.
TL;DR: In this article, a dual-band metamaterial antenna is proposed for wireless body centric communications, which is composed of a zeroth-order loop loaded periodically with mu-negative transmission line (MNG-TL) for a lower frequency band and a circular patch located in the center of loop for an upper frequency band.
Abstract: A compact low profile dual band metamaterial antenna is presented for wireless body centric communications. It is composed of a zeroth-order loop loaded periodically with mu-negative transmission line (MNG-TL) for a lower frequency band and a circular patch located in the center of loop for an upper frequency band. The MNG-TL loop based on the fundamental infinite wavelength property allows current along the loop to remain the same magnitude and phase to create omnidirectional radiation pattern in azimuth plane at the lower band for on-body communications. On the other hand, a unidirectional radiation pattern is generated by a circular patch in direction normal to a human body at the upper frequency band for off-body communications simultaneously. In order to feed the MNG-TL conveniently, a transition based on a CPW transmission line is proposed. Finally, the proposed antenna is fabricated and measured. It is demonstrated that the measurement has good agreement with simulation.
TL;DR: In this article, the S-parameters method for bi-anisotropic metamaterials effective constitutive parameters extraction is extended to oblique incidence, which enables to extract all unknown parameters using Sparameters measured over a single metammaterial slab.
Abstract: The S-parameters method for bi-anisotropic metamaterials effective constitutive parameters extraction is extended to oblique incidence. The proposed method enables to extract all unknown parameters using S-parameters measured over a single metamaterial slab. The bi-anisotropic metamaterial is a pseudochiral omega medium and assumed to have diagonal permittivity and permeability tensors. The extraction process suggested involves both analytical extraction equations and numerical optimization. This method is utilized to show the limited validity of the assumption of absence of spatial dispersion on which the proposed approach is based. The extraction method is demonstrated over bulk and artificial media such as SRR metamaterial and the results are validated with satisfactory agreement published data in the literature.
TL;DR: A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.
Abstract: The design of a compact metamaterial ultra-wideband (UWB) antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR), capacitive loaded strip (CLS) and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR) measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST)) and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.
TL;DR: In this article, a reduced size metamaterial loaded circular microstrip patch antenna is presented, where the complementary split ring resonator is loaded in the ground plane of the antenna.
Abstract: In this paper, the authors have presented a reduced size metamaterial loaded circular microstrip patch antenna. In the present work, complementary split ring resonator is loaded in the ground plane of circular microstrip patch antenna is. The unloaded circular microstrip patch antenna resonates at 6.11 GHz, whereas after loading it with complementary split ring resonator, the same antenna resonates near 6.11 GHz with reduced size. The effective footprint of the antenna is reduced by nearly 64% compared to the conventional patch antenna. The gain of the metamaterial loaded antenna structure is 5.04 dB.
TL;DR: In this article, the authors designed a miniaturized carved planar metamaterial antennas with special configurations for wide band FR, microwave, and wireless communication systems, where the E-shaped slits and the split ring resonator as spiral inductors perform the roles of the series LH capacitors and shunt LH inductors, respectively, so that by optimizing these elements in their numbers and dimensions, the good operational performances of antennas can be achieved.
Abstract: New concepts to designing the miniaturized carved planar metamaterial antennas with special configurations for wide band FR, microwave, and wireless communication systems are presented. To realize the proposed antennas, composite right/left-handed (RH/LH) transmission lines (TLs) as a general TLs possessing both LH) and RH natures are implemented by the standard manufacturing techniques, so the E-shaped slits and the split ring resonator as spiral inductors perform the roles of the series LH capacitors (CL) and shunt LH inductors (LL), respectively, so that by optimizing these elements in their numbers and dimensions, the good operational performances of antennas can be achieved. The proposed antennas are constructed using two and three unit cells with E-shaped layouts having overall dimensions of 0.017λ0 × 0.006λ0 × 0.001λ0 and 0.028λ0 × 0.008λ0 × 0.001λ0, where λ0 is free space wavelength at the operating frequencies of 500 and 650 MHz, respectively. The antennas cover the frequency bandwidths of 500 MHz–1.35 GHz (850 MHz) and 650 MHz–1.85 GHz (1.2 GHz), which correspond to 91.9% and 96.0% fractional bandwidths, respectively. Besides the small dimensions and wide bandwidth characteristics, the measured gains and efficiencies are 5.3 dBi and 85% at 1 GHz for the first antenna, and 5.7 dBi and 90% at 1.4 GHz for the second antenna. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2339–2344, 2015
20 Jun 2015
TL;DR: In this article, an electrically isolated split ring resonator was placed in an interpixelated fashion to form a metamaterial super cell, which can be configured to have only magnetic resonance at 0.59 GHz, only electrical resonance at 1.45 GHz, or both magnetic and electrical resonances at 0.375 GHz.
Abstract: Tunability in metamaterials has added a new dimension to the functionality and application scope for light–matter interaction in the subwavelength regime. Microelectromechanical-systems-based microactuators have been reported as the most straightforward and efficient means of achieving tunable metamaterials, but so far can provide tunability of only a single electromagnetic property. This has greatly limited its usage in applications requiring either simultaneous or independent control of multiple parameters, such as linear polarization switching, actively controlled refractive indices, bandwidth tunable filters, and modulators. Here, we place an electrically isolated split ring resonator and an electrical split ring resonator in an interpixelated fashion to form a metamaterial super cell. The proposed metamaterial can be configured to have only magnetic resonance at 0.59 THz, only electrical resonance at 0.45 THz, or both magnetic and electrical resonances at 0.375 THz. The frequency at which magnetic and electrical resonance occurs is selectively changed by appropriately biasing the signaling lines of respective resonators. The proposed approach can be extended to have as many resonators as desired in a single complex metamolecule. Each of the unit cells is independently addressed and can be programmed, thereby enabling multiple functionalities using a single metamaterial in the terahertz spectral region. We believe that our proposed approach will enable the realization of a wide range of actively controlled EM properties, especially for active control of refractive indices and its potential applications. It will also aid in the realization of the ultimate form of tunable metamaterial, the “THz programmable metamaterial,” which will likely be a disruptive technology in the near future.
TL;DR: In this article, two novel metamaterial-inspired antennas applied for 4G mobile communication are proposed, which have the advantages of simple fabrication, miniaturization and compactness, which can be applied to the 4G wireless mobile communication system.
Abstract: Two novel metamaterial-inspired antennas applied for 4G mobile communication are proposed in this letter. Antenna 1 takes a triangular electromagnetic resonator (TER) as its radiator fed by a coplanar waveguide (CPW). After the model building and simulation, three frequency bands of $1.78\sim 1.84~\hbox{GHz}$ , $2.34\sim 3.86~\hbox{GHz}$ and $5.75\sim 5.87~\hbox{GHz}$ are achieved. Each band is well matched except for the band 3. Therefore, Antenna 2 is further developed, which adds a complementary TER (CTER) on the ground, and the improved design has a good impedance matching in band 3 without influencing the first two bands. Both antennas have operational bands covering WiMAX in 1.8/3.5 GHz and WLAN in 5.8 GHz and omnidirectional radiation patterns during the operating bands. The proposed two metamaterials antennas have the advantages of simple fabrication, miniaturization and compactness, which can be applied to the 4G wireless mobile communication system.
TL;DR: In this paper, a spatial coordinate transformation is defined to transform the space containing a radiating element, which is able to change the radiation pattern and to make the radiation location appear outside the latter space.
Abstract: Complex electromagnetic structures can be designed by using the powerful concept of transformation electromagnetics. In this study, we define a spatial coordinate transformation that shows the possibility of designing a device capable of producing an illusion on an antenna radiation pattern. Indeed, by compressing the space containing a radiating element, we show that it is able to change the radiation pattern and to make the radiation location appear outside the latter space. Both continuous and discretized models with calculated electromagnetic parameter values are presented. A reduction of the electromagnetic material parameters is also proposed for a possible physical fabrication of the device with achievable values of permittivity and permeability that can be obtained from existing well-known metamaterials. Following that, the design of the proposed antenna using a layered metamaterial is presented. Full wave numerical simulations using Finite Element Method are performed to demonstrate the performances of such a device.