A compact dual‐band zeroth‐order resonator antenna loaded with meander line inductor

A novel zeroth‐order resonator (ZOR) meta‐material (MTM) antenna with dual‐band is suggested using compound right/left handed transmission line as MTM. In this article, suggested antenna consists of patch through series gap, two meander line inductors, and two circular stubs. The MTM antenna is compact in size which shows dual‐band properties with first band centered at 2.47 GHz (2.05‐2.89 GHz) and second band is centered at 5.9 GHz (3.70‐8.10 GHz) with impedance bandwidth of (S₁₁ < ? 10 dB) 34.69% and 72.45%, respectively. At ZOR mode (2.35 GHz), the suggested antenna has overall dimension of 0.197λ_o × 0.07λ_o × 0.011λ_o with gain of 1.65 dB for ZOR band and 3.35 dB for first positive order resonator band which covers the applications like Bluetooth (2.4 GHZ), TV/Radio/Data (3.700‐6.425 GHz), WLAN (5‐5.16 GHz), C band frequencies (5.15‐5.35, 5.47‐5.725, or 5.725‐5.875 GHz) and satellite communication (7.25‐7.9 GHz). The radiation patterns of suggested structure are steady during the operating band for which sample antenna has been fabricated and confirmed experimentally. It exhibits novel omnidirectional radiation characteristics in phi = 0° plane with lower cross‐polarization values.     

Novel electrically small meander line RFID tag antenna

This article introduces a new RFID tag antenna designed for operation at 915 MHz. The proposed antenna is electrically small with dimensions (λ₀/15) × (λ₀/15). It features two vivaldi‐like apertures flipped with respect to each other around an axis parallel to their slotted edges. Each aperture is loaded with a meander line with multiple loops. The two sides of the proposed antenna are fed via a common slot line that is coupled electromagnetically to a perpendicular microstrip line at the other side of a dielectric substrate. The new antenna are fabricated using printed circuit board technology and the fabricated prototype is experimentally characterized. The optimization and theoretical investigation of the proposed antenna are performed via both HFSS and CST. The two simulators agree very well with each other and with measurements. The characteristics of the new RFID antenna are generally good, such as: small size (22 mm²), low profile (0.8 mm), flexible impedance matching, reasonable impedance bandwidth (8%), omni‐directional radiation, low cross‐polarization level (?20 dB at broadside), acceptable radiation efficiency (76%), and gain (?0.3 dBi). © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 23: 639–645, 2013.     

Miniaturized dual‐band metamaterial inspired antenna with modified SRR loading

A miniaturized dual‐band CPW‐fed Metamaterial antenna with modified split ring resonator (SRR) loading has been presented in this paper. Proposed antenna comprises a tapered rectangular patch with a slot in which an elliptically SRR has been loaded to achieve miniaturization. Proposed antenna shows dual band operations in the operating band 3.25‐3.42 and 3.83‐6.63 GHz, respectively. It has been observed that lower mode (at 3.36 GHz) is originated by means of modified SRR. SRR is being modified by small meandered line inductor which is placed instead of strip. This provides an extra inductance to SRR resulting miniaturization. Overall electrical size of the proposed antenna is 0.222 × 0.277 × 0.017 λ₀ at 3.36 GHz. Second band is due to coupling between feed and ground planes. The antenna offers an average peak gain of 1.72 and 3.41 dB throughout the first and second band respectively. In addition to that this antenna exhibits perfect omnidirectional and dipolar radiation patterns at xz‐ and yz‐ plane respectively. Due to consistent radiation pattern, ease of fabrication, and compact nature this antenna can be used for wireless applications such as worldwide interoperability for microwave access (WiMAX), industrial, scientific and medical (ISM) band, WLAN/Wi‐Fi bands.     

Design of meander line inductors on printed circuit boards

A partial‐element circuit model for meander line inductors printed on circuit boards is proposed and its relation with the physical layout is derived. A procedure for the design is presented allowing to obtain inductances between 8 and 50 nH in the range from 30 to 1000 MHz with a 5% mean error. © 2001 John Wiley & Sons, Inc. Int J RF and Microwave CAE 11: 219–230, 2001.     

A novel meander line integrated E‐shaped rectenna for energy harvesting applications

In this article, design of a novel meander integrated E‐shaped rectenna is presented. The designed rectenna operates at ISM frequency range from 2.2 to 2.5 GHz with acceptable reflection coefficients, gain and VSWR values. The designed rectenna is simulated using HFSS 15 (High Frequency Electromagnetic Field Simulation) and FR4 epoxy material is used in rectenna design for low cost having dielectric constant of 4.4 and thickness of 1.6 mm. In the rectifying stage full wave voltage doubler circuit is designed for DC power generation with SMS7630 Schottky diode and lumped circuit elements. The impedance matching circuit between the antenna and the rectifier is designed and simulated using advanced design system (ADS) software for efficient power transmission from the antenna to the load. The simulation and measurement results with different load and input power levels prove that the designed and implemented system can be used for low power energy harvesting applications in order to feed electronic components and battery free sensor networks.     

A miniaturized ultra‐wideband planar monopole antenna with L‐shaped ground plane stubs

This article presents a miniaturized ultra‐wideband planar monopole antenna with an oval radiator. The proposed antenna is fed by a coplanar waveguide (CPW), and two L‐shaped stubs are extended from the ground plane of the CPW. This presented antenna is able to produce resonances in the lower frequency band and realize better impedance matching performance in the middle and higher frequency bands with the aid of the L‐shaped stubs. The antenna was built and tested. The total size of the proposed antenna is only 26 × 20 × 1.6 mm³. Its measured –10 dB impedance bandwidth is 10.1 GHz (3.1‐13.2 GHz). The measured far‐field radiation patterns are stable in the whole operating frequency band.     

High performance resonant cavity antenna with non‐uniform metamaterial inspired superstrate

The resonant cavity antenna (RCA) is a class of widely used high gain antennas, but usually suffers from narrow impedance bandwidth owing to its strong resonant property, as well as relatively low aperture efficiency because of its non‐uniform electromagnetic (EM) field distribution on the aperture. This article explores enhancing the RCA's impedance bandwidth and aperture efficiency by designing a non‐uniform metamaterial inspired superstrate, on which the metal patches vary their sizes with respect to their distances to the superstrate's center. After optimized by the Genetic Algorithm, the proposed RCA is designed, fabricated and tested. Measured results agree well with simulated ones and show that in comparison with a RCA with a uniform metamaterial inspired superstrate, this work significantly improves the |S ₁₁| < ?10 dB impedance bandwidth from 2.1% to 6.1%, the gain at the working frequency 10 GHz from 19.07 dBi to 20.55 dBi, and correspondingly the aperture efficiency from 50.5% to 71%. A further analysis estimates that due to the non‐uniform metamaterial inspired superstrate, a more homogeneous distribution for both the amplitude and phase of the EM field is observed on the superstrate's aperture.     

Compact meander T‐shaped monopole antenna for dual‐band WLAN applications

A compact coplanar waveguide‐feed monopole antenna with dual‐band characteristics is proposed in this article. The proposed antenna mainly consists of meander T‐shaped monopole and small ground plane embedded with a pair of L‐shaped couple slots and two pairs of I‐shaped notched slots symmetrically. By elongating the meander T‐shaped arms and carefully selecting the positions and lengths of L‐shaped slot and I‐shaped slot, the antenna excites four resonant frequencies at 2.42, 2.52, 4.75, and 5.54 GHz which are formed into two wide bands to cover all the 2.4/5.2/5.8 GHz wireless local area network (WLAN) operating bands, and is with miniaturization structure. Moreover, the antenna can provide nearly dipole‐like radiation patterns and good gains across the dual operating bands. These results prove that the proposed dual‐band antenna is very suitable for WLAN applications. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.     

CPW fed miniaturized dual‐band short‐ended metamaterial antenna using modified split‐ring resonator for wireless application

A miniaturized dual‐band metamaterial (MTM) antenna has been designed in this article. The designed coplanar waveguide fed antenna has composed of inner split‐ring resonator and an outer open ring resonator with rectangular stub. The series parameter of the antenna is used to determine the zeroth order resonance frequency due to short‐ended boundary condition. The whole size of proposed structure is 20 × 25.5 mm². This MTM antenna exhibits dual‐band operation at 3.17 GHz (3.1–3.22 GHz) and 5.39 GHz (5.27–5.47 GHz). The proposed MTM structure achieves measured peak gain of 0.71 and 1.89 dB at 3.17 and 5.39 GHz, respectively. The proposed antenna can be used for recent radio communication in form of S‐band application and Wi‐MAX.     

Modeling double‐side printed meander‐line inductors on printed circuit boards

A lumped element model for a double‐side printed meander‐line inductor with closed‐ form expressions for the electrical model parameters L, C, R_l, and R_c is presented. These structures are cheaper than coils and need less area per unit of inductance than single‐side printed meander‐line inductors. The model has been validated with measurements from 30 to 1000 MHz, finding a mean error in the inductance parameter of about 1%. © 2003 Wiley Periodicals, Inc. Int J RF and Microwave CAE 13: 105–112, 2003.     

Complementary meander‐line‐inspired dielectric resonator multiple‐input‐multiple‐output antenna for dual‐band applications

The communication presents a simple dielectric resonator (DR) multiple‐input‐multiple‐output (MIMO) dual‐band antenna. It utilizes two “I”‐shaped DR elements to construct an “I”‐shaped DR array antenna (IDRAA) for MIMO applications. The ground plane of the antenna is defected by two spiral complementary meander lines and two circular ground slots. In the configuration, two “I”‐shaped DR elements are placed with a separation of 0.098λ. The antenna covers dual‐band frequency spectra from 3.46 to 5.37 GHz (43.26%) and from 5.89 to 6.49 GHz (9.7%). It ensures the C‐band downlink (3.7‐4.2 GHz), uplink (5.925‐6.425 GHz), and WiMAX (5.15‐5.35 GHz) frequency bands. Each DR element is excited with a 50‐Ω microstrip line feed with aperture‐coupling mechanism. The antenna offers very high port isolation of around 18.5 and 20 dB in the lower band and upper band, respectively. The proposed structure is suitable to operate in the MIMO system because of its very nominal envelope correlation coefficient (<0.015) and high diversity gain (>9.8). The MIMO antenna provides very good mean effective gain value (±0.35 dB) and low channel capacity loss (<0.35 bit/s/Hz) throughout the entire operating bands. Simulated and measured results are in good agreement and they approve the suitability of the proposed IDRAA for C‐band uplink and downlink applications and WiMAX band applications.     

Design and application of composite right/left‐handed transmission line based on complementary meander archimedean spiral resonator

A novel composite right/left‐handed transmission line based on the complementary meander Archimedean spiral resonator (CMASR) is proposed and investigated in detail. The composite property of the proposed structure is demonstrated and the right‐handed frequency band is initially pointed out for the structure derived from the complementary Archimedean spiral resonator (CASR). One modified method of extracting the lumped elements based on the analytical analysis is proposed to investigate the equivalent circuit model. The results indicate that this method can accelerate the extracting process effectively and the circuit model using the extracted elements can predict the property of the given structure excellently. Then, the influence of primary geometrical parameters is investigated through the parametric analysis, which provides the directive guideline. When compared with CASR, CMASR can lower the operating frequency further with keeping the effective area roughly constant. To explore and validate the composite property, one broadband bandpass filter is designed through tuning the left‐ and right‐handed frequency bands into the quasi‐balance condition. The measured results indicate that the fractional bandwidth is about 88.3%. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE , 2012.     

Broadband cloaking with transmission‐line networks and metamaterial

Cloaking objects by transmission line and metamaterial is presented. Simulation results reveal that the bandwidth of this method is increased by embedding the transmission networks in a medium whose refractive index is smaller than unity. The low refractive index medium is realized by embedding thin wires in a host medium. © 2012 Wiley Periodicals, Inc. Int J RF and Microwave CAE 22: 663–668, 2012.     

Metamaterial inspired CPW‐fed compact antenna for ultrawide band applications

A small size, planar and co‐planar waveguide fed metamaterial inspired antenna is proposed for ultra‐wideband (UWB) application. The main radiating element consists of three split‐ring resonators (SRR) and placed along one axis. Moreover, coplanar waveguide (CPW)‐fed line along with modified ground plane is used to improve the impedance matching. The physical size of proposed antenna is 25(W) × 22 (L) × 1.6 (H) mm³. The CPW‐fed metamaterial inspired antenna provides bandwidth of 10.4 GHz from 3.1 to 13.5 GHz based on the 3:1 (voltage standing wave ratio [VSWR] <2). Over the range of UWB frequency, peak realized gain varies from 2.5 to 4 dBi. The proposed antenna provides omnidrectional radiation patterns. Further, fidelity factor of the proposed antenna is also calculated and measured. The calculated fidelity factor is suitable for UWB applications. Finally, prototype of the antenna is developed and tested using network analyzer. The simulated and measured results are in good agreement.     

A Multiband antenna using plus‐shaped fractal‐like elements and stepped ground plane

A multiband planar symmetrical plus‐shaped fractal monopole antenna with stepped ground plane is presented in this study. Measured results show that the proposed antenna operates with 10 dB return loss bandwidths from 1.630 to 1.88 GHz and from 4.5 to 8.5 GHz covering The Global System for Mobile Communications (GSM) 1800 MHz 2G spectrum band, 4400 to 4900 MHz 5G spectrum band adopted by Japan and China for future 5G communication in sub‐6 GHz band, 5.15 to 5.925 GHz LTE band 46, WLAN IEEE 802.11 y/a/h/j/n/P bands, and 5.8 to 7.707 GHz military band. The antenna gain varies between 1.73 and 1.97 dB in lower band and 3.6 to 5.05 dBi in upper band with radiation efficiencies more than 90% in lower band and more than 80% in upper band. The antenna has more than 64 and 28 dB isolations between the copolar and cross‐polar radiation patterns in the lower and upper bands, respectively.     

Wideband microstrip‐based wearable antenna backed with full ground plane

A wideband microstrip‐based wearable antenna with a fractional bandwidth of 51% is designed using textile materials for wearable applications. The antenna operates between 2 and 3 GHz with low back‐radiation to ensure minimum coupling to the body and reduced electromagnetic power absorption in the human tissue. The behavior microstrip antenna topology, which is narrowband in nature, is altered via the combinations of various broadbanding techniques, while maintaining the existence of the full ground plane backing. This ensures that the antenna radiation is directed outward form the body to efficiently propagate wireless signals toward other off‐body nodes and base stations. Simulation and measurement results indicated that the use of this microstrip topology with multiple broadbanding techniques is capable of reducing the back lobe, resulting in a front‐to‐back ratio of about 17 dB and a 3.5 dBi of average gain.     

Triple‐band metamaterial‐inspired antenna using FDTD technique for WLAN/WiMAX applications

In this article, a triple‐band metamaterial (MTM)‐inspired antenna has been designed and analyzed using finite difference time domain technique (FDTD). The proposed MTM consists of two L‐dumbbell‐shaped unit cells, feed, and partial ground plane. The proposed antenna shows triple‐band characteristics with impedance bandwidths of 10.6, 4.67, and 26.8% centered at 2.4, 3, and 5.7 GHz, respectively. The first two bands are working at zeroth‐order resonating mode and first‐order resonating mode while third is due to series slot and coupling between feed and ground plane. It offers compact nature with total antenna size of 30 × 30 × 1.6 mm³. The proposed triple‐band antenna has been designed and analyzed using FDTD code based on convolutional perfectly matched layer boundary conditions and HFSS as well. The prototype antenna has also been fabricated and tested experimentally to validate the simulation results. The proposed antenna exhibits good radiation characteristics throughout the working bands. © 2015 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:688–695, 2015.     

Compact slot‐loaded ultra‐wideband multiple‐input multiple‐output antenna with fractal‐inspired isolator

In this paper, a compact multielement ultra‐wideband (UWB) multiple‐input multiple‐output (MIMO) antenna is presented. The proposed antenna is designed by integrating novel technique of stub‐loaded slot, split square ring (SSR), and fractal‐inspired isolator. The antenna size is effectively miniaturized by implementing three‐sided symmetrical stub‐loaded Koch slot and square split ring. The impedance bandwidth is broadened by using small notched partial ground plane. The mutual coupling between the element is impressively reduced by isolating the structure with a Sierpinski fractal. As a result, the proposed antenna achieves a UWB response with a very broad impedance bandwidth of 3.1 to 19 GHz. Moreover, the proposed antenna obtains high peak stable gain and diversity gain of up to 10 dBi, lower group delay (<1 ns), and lower envelop correlation coefficient of <.01. The proposed antenna has electrically small dimensions of 35 × 53 × 0.8 mm. With this low‐profile configuration, the proposed antenna is especially a good candidate for portable UWB‐MIMO wireless communication system.     

Study of miniaturized E‐patch antenna loaded with novel E‐shape SRR metamaterial for RFID applications

A new design of compact micro strip antenna, based on a newly structure "E"SRR of metamaterial is proposed and designed using CST Microwave Studio. It has been found that the characteristics of new micro strip antenna with novel designed metamaterials placed in the same plane as the radiating element are comparable to the conventional patch antennas, whereas its gain, directivity, and radiating efficiency are remarkably improved. For the design and fabricated antenna, it shows that with the addition of split ring resonator, the frequency has been shifted from 2.38 GHz to 2.4 GHz. The return loss of this antenna increased from ?60 dB to ?70 dB. The realized gain increased from 7.1 dbi for the antenna alone to 7.31 dbi for the meta‐material antenna. Prototype for all antennas are fabricated and measured. Good agreement between the measured and simulated results is achieved.     

A compact dual‐band 2 × 1 metamaterial inspired mimo antenna system with high port isolation for LTE and WiMax applications

This article proposes a compact (43 × 26 × 0.8 mm³) dual‐band two‐element metamaterial‐inspired MIMO antenna system with high port isolation for LTE and WiMAX applications. In this structure, each antenna element consists of a square–ring slot radiator encircling a complementary split ring resonator. A tapered impedance transformer line feeds these radiating apertures and shows good impedance matching. A 2 × 3 array of two‐turn Complementary Spiral Resonator structure between the two antenna elements provides high dual‐band isolation between them. The fabricated prototype system shows two bands 2.34 – 2.47 GHz (suitable for LTE 2300) and 3.35 – 3.64 GHz (suitable for WiMAX). For spacing between two antennas of 10 mm only, the measured isolation between the two antenna elements in the lower band is around ?32 dB while that in the upper band is nearly 18 dB. The system shows a doughnut‐shaped radiation patterns. The peak measured antenna gains for the proposed MIMO system in the lower and higher bands are 3.9 and 4.2 dBi, respectively. The MIMO system figure of merits such as the envelope correlation coefficient, total efficiency are also calculated and shown to provide good diversity performance.