Showing papers in "Aeu-international Journal of Electronics and Communications in 2017"

FPGA implementation of two fractional order chaotic systems

Abstract: This paper discusses the FPGA implementation of the fractional-order derivative as well as two fractional-order chaotic systems where one of them has controllable multi-scroll attractors. The complete hardware architecture of the Grunwald-Letnikov (GL) differ-integral is realized with different memory window sizes. As an application of the proposed circuit, a complete fractional-order FPGA implementation of Liu chaotic system is introduced with different fractional-orders. Moreover, a fractional-order controllable heart and V-shape multi-scrolls chaotic systems are verified in the case of symmetric and asymmetric cases. Different interesting attractors are realized under various parametric changes with distinct step sizes for different fractional-orders. To verify the chaotic behavior of many generating attractors, the Maximum Lyapunov Exponent (MLE) is calculated for such systems. The designs have been simulated using Xilinx ISE 14.5 and realized on Xilinx FPGA Virtex 5 XC 5 VLX 50 T . The achieved throughputs are: 4.4 Gbit/s for GL, 1.986 Gbit/s for Liu system, and 2.921 Gbit/s for V-Shape multi-scroll attractor.

A blind DCT based color watermarking algorithm for embedding multiple watermarks

Abstract: Multiple watermarking based techniques are receiving more attention in recent times for its wide variety of applications in different fields. To protect the copyright ownership and validate the authenticity of multiple owners, in this paper a color multiple watermarking method based on DCT (Discrete Cosine Transform) and repetition code is proposed and simulated. Initially, green and blue components of color host image are selected for inserting multiple watermarks. Then, each green and blue component of the image is decomposed into non overlapping blocks and subsequently DCT is employed on each block. In this technique, a binary bit of watermark is embedded into green/blue component’s transformed block by modifying some middle significant AC coefficients using repetition code. During multiple watermarks embedding in green and blue components of the proposed method, DC and some higher AC coefficients are kept intact after zigzag scanning of each DCT block to ensure the imperceptibility of the watermarked host image. The proposed scheme is experimented to establish the validity by extracting adequate multiple watermark data from the restructured cover image after applying common geometric transformation attacks (like rotation, cropping, scaling and deletion of lines/columns etc.), common enhancement technique attacks (like lowpass filtering, histogram equalization, sharpening, gamma correction, noise addition etc.) and JPEG compression attacks.

A compact double-sided MIMO antenna with an improved isolation for UWB applications

Abstract: This paper presents compact size 4 × 4 cm 2 MIMO antenna for UWB applications. The proposed antenna consists of four symmetric circular elements printed on low cost FR4 substrate with partial slotted ground plane. The two sides of the substrate are symmetric and each side is consisting of two radiators with the partial ground planes associated to the two other elements mounted on the other side. The two elements of the front side are orthogonal to the two other elements of the back side in order to increase the isolation between elements. For further reduction in the mutual coupling between elements, decoupling structures are presented in the top and bottom layers of the substrate. The simulated and measured results are investigated to study the effectiveness of the MIMO-UWB antenna. The results demonstrate the satisfactory performance of MIMO-UWB antenna, which has a return loss less than −10 dB from approximately 3.1 GHz to more than 11 GHz with an insertion loss lower than −20 dB through the achieved frequency band, and a correlation less than 0.002. Moreover, the proposed MIMO model exhibits a nearly omni-directional radiation pattern with almost constant gain of average value 3.28 dBi.

Energy efficient path selection for mobile sink and data gathering in wireless sensor networks

Abstract: Mobile sink (MS) has drawn significant attention for solving hot spot problem (also known as energy hole problem) that results from multihop data collection using static sink in wireless sensor networks (WSNs). MS is regarded as a potential solution towards this problem as it significantly reduces energy consumption of the sensor nodes and thus enhances network lifetime. In this paper, we first propose an algorithm for designing efficient trajectory for MS, based on rendezvous points (RPs). We next propose another algorithm for the same problem which considers delay bound path formation of the MS. Both the algorithms use k -means clustering and a weight function by considering several network parameters for efficient selection of the RPs by ensuring the coverage of the entire network. We also propose an MS scheduling technique for effective data gathering. The effectiveness of the proposed algorithms is demonstrated through rigorous simulations and comparisons with some of the existing algorithms over several performance metrics.

New analog implementation technique for fractional-order controller: A DC motor control

Abstract: This paper deals with a new method for analog implementation of the fractional-order controller using an active element in form of the Operational Transconductance Amplifier. Transfer function of such controller is performed by the Inverse-Follow-the-Leader-Feedback topology. Presented implementation is resistorless, energy effective and suitable for realization in integrated form. Proposed and implemented fractional-order controller is used for a DC motor control. Obtained simulation results in frequency and time domains are presented as well.

A 860 kHz grounded memristor emulator circuit

Abstract: A grounded memristor emulator circuit operating from 16 Hz to 860 kHz is proposed. The emulator circuit is built around a plus-type second generation current conveyor, a four quadrant analog multiplier, a capacitor and a resistor. Two DC voltage sources are used for controlling the zero crossing of the frequency-dependent pinched hysteresis loop over a broad range of amplitude A m of the input signal, and principally when the memristor emulator circuit is operating at high-frequency. It describes in detail the derivation of the behavioral model of the proposed emulator circuit, including parasitic elements and showing that the charge-controlled memductance is a first-order function. Furthermore, a design guide to choose the numerical value of each discrete element in function of the operating frequency and A m is also given. The emulator circuit is built with off-the-shelf devices, and numerical results obtained by means of the behavioral model are compared with HSPICE simulations and experimental tests, showing good agreement among all them in a wide range of frequencies. This is against with some memristor emulator circuit available in the literature which present a good behavior at low-frequency and however, the zero crossing of the pinched hysteresis loop is deviated when the operating frequency increases. It is worth to stress that for the best knowledge of the authors, this is the first memristor emulator circuit that is operating to high-frequency. Moreover, the proposed emulator circuit can be configured as decremental or incremental memristor in order to be used in future applications such as cellular neural networks, modulators, sensors, chaotic systems, relaxation oscillators, nonvolatile memory devices and programmable analog circuits.

Memristor emulator with tunable characteristic and its experimental results

Abstract: In this study, operational transconductance amplifier (OTA) based simple and practical TiO2 memristor emulator is presented. The proposed memristor emulator employs a multi-outputs OTA, an analog multiplier and a resistor and a capacitor. The parameters of the proposed memristor emulator can be tuned electronically by changing the biasing current of the OTA. Change of the transconductance gain of the OTA provides an advantage: “externally controllable memristor”. Non-volatile resistive switching characteristics and an application of this proposed memristor are given. Also, the memristor emulator is implemented using the commonly available OPA860. The effectiveness of the proposed memristor emulator is verified by the experimental results, which show good agreement with the theoretical and simulation results.

Synchronization and chaos in coupled memristor-based FitzHugh-Nagumo circuits with memristor synapse

Abstract: The memristor has drawn a significant interest in the fields of neuromorphic circuits because the nanoscale memristor is a strong candidate to become the critical element of novel ultra-high density low-power non-volatile memories. In the present paper, we focus on networks of FitzHugh-Nagumo neuron circuits employing memristor. First, we build the memristor-based circuit of FitzHugh-Nagumo model. The details of the chaotic phenomena of the memristor-based FitzHugh-Nagumo circuit under external stimuli have been found with use of computer simulations, i.e., we have numerically calculated waveform diagrams, phase portraits, Lyapunov exponents and bifurcation diagram. And we also confirm these results of theoretical analyses and numerical calculations by circuit simulation experiments of the actual analog circuit realization using Multisim modeling. Then the synchronization of coupled memristor-based chaotic neurons with memristor synapse is discussed, and synchronization mechanism is also found. Finally, we have also derived the sufficient conditions of chaotic synchronization in unidirectional coupled neuron circuits and bidirectional coupled neuron circuits respectively, which are that the parameter of memristor synapse must meet certain conditions. These results of theoretical analyses have been confirmed by numerical simulation.

Energy efficient cross layer based adaptive threshold routing protocol for WSN

Abstract: Wireless Sensor Networks (WSNs) perform an important part in modern day communication as it can sense the various physical and environmental parameters by employing low cost sensor devices. The growth of the networks due to scientific advancements have altogether made it possible to create an energy efficient cross layer network that can improve its lifespan. In this paper, a routing protocol is proposed for the networks which are heterogeneous and are based on the adaptive threshold sensitive distributed energy efficient cross layer routing protocol. The concept of weighted probability is used to assign the CH (Cluster Head) of the network cluster. The proposed algorithm is simulated, tested and compared with previously established routing protocols and has shown enhanced results and prolonged network lifespan. In the proposed protocol, a combination of the proactive and reactive network is considered for effective data transmission.

A systematic procedure for deriving RC networks of fractional-order elements emulators using MATLAB

Abstract: The behavior of a fractional-order capacitors can be approximated using appropriately configured RC networks, which implement an integer-order impedance/admittance function. In this paper, the Foster I and II as well as the Cauer I and II structures are systematically derived using the MATLAB software. In addition, the emulation of fractional-order inductors using RC emulators of fractional-order capacitors and Generalized Impedance Converter is performed. The behavior of the derived RC networks is evaluated and compared through a design example, using the OrCAD PSpice software, in order to choose the most appropriate among them.

A miniaturized metamaterial slot antenna for wireless applications

Abstract: A novel miniaturized five band metamaterial inspired slot antenna is reported. The proposed design consists of a ring monopole and metamaterial Rectangular Complementary Split Ring Resonator (RCSRR) as the radiating part, two L and one T–shaped slot as the ground plane, respectively. Miniaturization in the proposed design is accomplished by metamaterial RCSRR, and also, it helps the antenna to operate at 2.9 and 5.2 GHz frequency bands. The aforementioned miniaturization process leads to about 46.8% reduction in volume of the proposed design, as compared to the conventional antenna. The pass band characteristics of the metamaterial RCSRR through waveguide medium are discussed in detail. In order to enhance the operating abilities of the miniaturized antenna, slots are etched out in the ground plane, thereby making the miniaturized antenna further operate at 2.4, 5.6 and 8.8 GHz, respectively. The proposed design has an active patch area of only , with dB bandwidth of about 4.16% (2.35–2.45 GHz), 5.71% (2.63–2.76 GHz), 10.25% (4.44–4.92 GHz), 6.25% (5.42–5.77 GHz) and 2.39% (8.68–8.89 GHz) in simulation, and about 6.86% (2.25–2.41 GHz), 5.01% (2.55–2.7 GHz), 9.16% (4.58–5.02 GHz), 5.38% (5.79–6.11 GHz) and 5.42% (8.44–8.91 GHz) in measurement. The antenna has good impedance matching, acceptable gain and stable radiation characteristics across the operational bandwidths.

A simple three-dimensional fractional-order chaotic system without equilibrium: Dynamics, circuitry implementation, chaos control and synchronization

Abstract: Chaotic systems without equilibrium points have been investigated and received significant attention recently. In this work, we propose a new three-dimensional fractional-order chaotic system without equilibrium. Dynamics of the fractional-order system are investigated and a circuit implementation of the system by using electronic components is presented. Interestingly, bistable chaotic attractors of such fractional system are discovered. In addition, we are able to control and synchronize the system by using active control and unidirectional coupling.

Experimental comparison of integer/fractional-order electrical models of plant

Abstract: In this paper, different integer and fractional-order models are studied from electrical point of view, these models are used to fit the measured impedance data for different types of fruits and vegetables. Experimental work is done on eight different models for six types of fruits to verify the best fitting model. Electric impedance is measured in the range of frequencies (200 mHz–200 Khz) using a non-destructive method, where the tissues are not damaged by electrode insertion. Moreover, two integer order models have been extended to the fractional order domain where data analysis and fitting are applied. The extra degrees of freedom of the fractional order models have enhanced the fitting parameters showing better accuracy. The double Cole Model has been found to be the best fit among different integer and fractional models based on root mean square error (RMSE).

Memristor emulator circuits using single CBTA

Abstract: In this paper, new analog memristor emulator circuits based on current backward transconductance amplifier (CBTA) and passive elements are proposed. They emulate both types of memristor (incremental and decremental) just by interchanging the CBTA output terminals. It uses only one CBTA, two resistors, one capacitor and one multiplier emulating grounded memristor. They consist of less CMOS transistors and have wider output ranges compared to other designed emulator circuits. The CMOS implementation of the CBTA using 0.18 μm level-7 TSMC CMOS technology parameters is also proposed. It uses 23 CMOS transistors operating with the ±0.9 V DC supply voltage. Theoretical derivations and related results are validated using SPICE simulations.

Generalized fractional logistic map encryption system based on FPGA

Abstract: This paper introduces the design of a generalized fractional order logistic map suitable for pseudorandom number key generators and its application in an encryption system based on FPGA. The map is generalized through two parameters ( a , b ) where complete analysis of their effect on the map is detailed, which gives more control on the map chaotic regions. The vertical map and the zooming map presented in this paper are two special maps extracted from the generalized map with their detailed analysis. Not only the positive bifurcation, but also the negative side is discussed through this paper, covering the complete diagram. The specifications of the introduced special logistic maps are proved to be completely controlled through eight design problems with their Lyapunov exponent. As an application, these eight designs are used for the key generation to encrypt different images through a simple algorithm. The correlation coefficients (horizontal, vertical, and diagonal) of the encryption system proposed, as well as the response to differential attacks are calculated. The sensitivity analysis proves that the encryption algorithm develops high sensitivity to the fractional-order key, which appears from the wrong decryption with 0.001% change of any system parameter. The encryption system is implemented on a Virtex-5 FPGA, XC5VLX50T, with a maximum clock frequency equal to 58.358 MHz.

Dynamics and circuit realization of a no-equilibrium chaotic system with a boostable variable

Abstract: Recent evidence suggests that there exists chaos in a few no-equilibrium systems A chaotic system without equilibrium is proposed and studied in this work It is worth noting that due to the absence of equilibrium, such a system belongs to a class of systems with hidden attractor Dynamics properties and the feasibility of the system are investigated by using numerical simulations and circuit implementation Interestingly, this no-equilibrium system has one variable with the freedom of offset boosting

A survey on fault diagnosis of analog circuits: Taxonomy and state of the art

Abstract: Due to the wide range of applications of electronic circuits in the recent years, the fault diagnosis in electronic circuits is a foremost problem. The main purpose of the fault diagnosis technique is isolating the faults present in the electronic circuits and also, detecting the fault which affects the safety and performance of the system. For various real-time applications of fault diagnosis, literature presents several techniques for detecting the faults in electronic circuits. In this paper, reviews on the research based on the fault diagnosis techniques which are all gained much attention are comprehended. Accordingly, 114 research papers related to the fault diagnosis are reviewed and analyzed based on the various objectives. In this review, we present the taxonomy of the fault detection in analog circuits and discuss the state of the art algorithms with various advantages and major drawbacks. The comprehensive analysis is carried out on finding the coverage of the publishers, faults, circuits, methods, simulation tools, and metrics. This critical review finally discusses the research challenges that are still available in the existing techniques and the way to extend the current research is also examined.

Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications

Abstract: This article presents a small, low-profile planar microstrip antenna that is applicable for both WLAN and WiMAX applications. The goal of this paper is to design an antenna which can excite triple-band operation with appreciable impedance bandwidth to combine WLAN/WiMAX communication specifications simultaneously in one device. The designed antenna has a compact size of 10 × 26 mm 2 . The proposed antenna consists of an inverted U-shaped slot radiator and a defected ground plane. Overall the design method and parametric study found appropriate dimensions, which provides three distinct bands I from 2.40 to 2.52, II from 3.40 to 3.60 and III from 5.00 to 6.00 GHz that covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. Finally, a prototype antenna was fabricated and experimentally characterized to verify the design concept as well as to validate the simulation results. Thus the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN and WiMAX frequency bands.

Single DVCCTA based high frequency incremental/decremental memristor emulator and its application

Abstract: Memristor emulator based on TiO 2 model is introduced. The proposed circuit uses current mode building block DVCCTA (Differential Voltage Current Conveyor Transconductance Amplifier) using 0.25 µm CMOS technology. The presented circuit uses single CMOS based DVCCTA, three resistors and one capacitor. It can operate up to 1 MHz in both the incremental and decremental configuration by interchanging the connections. Theoretical analysis of the proposed circuit resulting in the equivalent memristance equation is done and non-ideal analysis is also included. PSPICE simulations are performed. Simulation results agree well with theoretical assumption. To verify the practicability of the circuit, PCB prototype has been made using AD844AN and CA3080. The experimental demonstration is carried out for 50 kHz and 100 kHz. Moreover, the circuit has also been tested for non-volatility features. It is observed from the experimental test result and using 0.25 µm CMOS technology that maximum frequency is 10 kHz and 50 kHz respectively. To check the functionality of the circuit two combinations of memristor are connected in serial and parallel and desired results are obtained. Memristor based high pass filter is also discussed so as to study the memristor behavior in comparison to the resistor.

Biological Inspired Optimization Algorithms for Cole-Impedance Parameters Identification

Abstract: This paper introduces new meta-heuristic optimization algorithms for extracting the parameters of the Cole-impedance model. It is one of the most important models providing best fitting with the measured data. The proposed algorithms inspired by nature are known as Flower Pollination Algorithm (FPA) and Moth-Flame Optimizer (MFO). The algorithms are tested over sets of both simulated and experimental data. The results are compared with other fitting algorithms such as the Non-linear least square (NLS) and Bacterial Foraging Optimization (BFO). The comparison showed a better fit in the sum of absolute error sense (SAE) which consolidate the effectiveness of these new algorithms in the extraction process.

Real time implementation of fractional order PID controllers for a magnetic levitation plant

Abstract: Fractional calculus has been a topic of great interest for the last few decades The applications of fractional calculus can be found in the area of viscoelastic and chaotic systems, whose dynamics is expressed in the form of fractional differential equations The ongoing research work is based on the design of 1-Degree of Freedom (1-DOF) and 2-Degrees of Freedom (2-DOF) Fractional Order PID (FOPID) controllers for a Magnetic levitation (Maglev) plant and the performance has been compared with that of 1-DOF and 2-DOF Integer Order PID (IOPID) controllers in both simulation and real time The Degree of Freedom (DOF) represents the number of feed-forward control loops in a closed loop system A 2-DOF controller configuration comprises of a serial compensator and a feed-forward compensator in a closed loop structure An FOPID controller has a structure similar to that of a conventional IOPID controller, except that its derivative and integral orders are fractional numbers The design of such a controller requires the determination of five parameters: Kp, Ki, Kd, α and β, where α and β are the derivative and integral orders of the FOPID controller The controller design problem has been framed as an optimization problem, in which the cost function is formulated from the characteristic equation of the closed loop system at dominant poles that are identified from the given performance specifications The closed loop response shows that the proposed2-DOF FOPID controller exhibits superior response and robustness with respect to its integer order counterpart

Memristor emulator with spike-timing-dependent-plasticity

Abstract: A novel fully floating memristor circuit that accounts for the Spike Timing-Dependent Plasticity (STDP) mechanism is presented in this paper. This proposed circuit does not need any multiplier or extra circuit blocks to provide non-linear characteristics and transistors, which are operated in subthreshold region. We show that memristor circuit exhibits pinched-hysteresis loop in the V-I plane when driven by any sinusoidal voltage source. We demonstrate that the conductance change of the proposed floating memristor exhibits STDP behavior after the application of a pulse-pair train. Finally we present that the time constant of the STDP learning window can be controlled using only one parameter. Proposed memristor emulator circuit that accounts for STDP characteristics is compatible with VLSI systems.

Discrimination of natural images and computer generated graphics based on multi-fractal and regression analysis

Abstract: The aim of the work presented in this paper is to discriminate natural images (NI) and computer generated graphics (CG). The texture differences are analyzed to the residual images of NI and CG. The residual images are first extracted by using multiple linear regressions, and then the fitting degree of the regression model is investigated. Through the analysis of the difference of their residual images, 9 dimensions of histogram features and 9 dimensions of multi-fractal spectrum features are extracted to represent their texture differences. Combined with 6 dimensions of regression model fitness features, natural images and computer generated graphics are discriminated by using a support vector machine (SVM) classifier. Experimental results and analysis show that it can achieve an average identification accuracy of 98.69%, and it is robust against JPEG compression, rotation, additive noise and image resizing. Compared with some existed methods, the selection of features is effective and fewer features are required for representing the differences between NI and CG. Meanwhile, the classification time is significantly reduced and the robustness is maintained. It has great potential to be used in image source pipeline identification.

Hybridized ABC-GA optimized fractional order fuzzy pre-compensated FOPID control design for 2-DOF robot manipulator

Abstract: The robotic manipulator is an extremely nonlinear, multi-input multi-output (MIMO), highly coupled, and complex system wherein the parameter uncertainties and external disturbances adversely affect the performance of this system. From this, it necessitates that the controllers designed for such system must overcome these complexities. In this paper, we develop a novel fractional order fuzzy pre-compensated fractional order PID (FOFP-FOPID) controller for 2-degree of freedom (2-DOF) manipulator dealing with trajectory tracking problem. In order to optimize the controller’s parameters while minimizing integral of time absolute error (ITAE), a metaheuristic optimization technique, viz., artificial bee colony-genetic algorithm (ABC-GA) is presented. The efficacy of our proposed controller is demonstrated by comparing it with some existing controllers, such as integer order fuzzy pre-compensated PID (IOFP-PID), fuzzy PID (FPID), and conventional PID controllers. Furthermore, the robustness analysis for proposed controllers is also investigated for parameter variations and external disturbances. The simulation results indicate that FOFP-FOPID controller can not only guarantee the best trajectory tracking but also ameliorate the system robustness for parameter variations as well as external disturbances.

Design, fabrication and measurement of triple band frequency reconfigurable antennas for portable wireless communications

Abstract: In this paper two triple-band monopole antennas are proposed for portable wireless applications such as WiFi, WiMAX and WLAN. Two different geometrical structures are used for the radiating elements of these antennas, each printed on a low cost FR-4 substrate. Truncated metallic copper ground is used to attain optimum radiation pattern and better radiation efficiency. The frequency of the antennas is reconfigured using a lumped-element switch. The proposed antennas covers three frequency bands 2.45, 3.50 and 5.20 GHz depending upon the switching conditions. Both antennas works with an optimum gain (1.7–3.4 dB), bandwidth (6–35%), VSWR (

Analysis of nanometer-scale InGaAs/InAs/InGaAs composite channel MOSFETs using high-K dielectrics for high speed applications

Abstract: The outstanding electron transport properties of InGaAs and InAs semiconductor materials, makes them attractive candidates for future nano-scale CMOS. In this paper, the ON state and OFF state performance of 30 nm gate length InGaAs/InAs/InGaAs buried composite channel MOSFETs using various high-K dielectric materials is analyzed using Synopsys TCAD tool. The device features a composite channel to enhance the mobility, an InP spacer layer to minimize the defect density and a heavily doped multilayer cap. The simulation results show that MOSFETs with Al 2 O 3 /ZrO 2 bilayer gate oxide exhibits higher gm/I D ratio and lower sub threshold swing than with the other dielectric materials. The measured values of threshold voltage (V T ), on resistance (R ON ) and DIBL for Lg = 30 nm In 0.53 Ga 0.47 As/InAs/In 0.53 Ga 0.47 As composite channel MOSFET having Al 2 O 3 /ZrO 2 (EOT = 1.2 nm) bilayer dielectric as gate oxide are 0.17 V, 290 Ω-µm, and 65 mV/V respectively. The device displays a transconductance of 2 mS/µm.

Investigation of chaos in fractional order generalized hyperchaotic Henon map

Abstract: Dynamical analysis and chaos control of the fractional order generalized hyperchaotic Henon map is the main contribution of this paper. With a brief introduction to discrete fractional calculus, which is a new area of research in fractional calculus; we describe the fractional order version of generalized hyperchaotic Henon map. The classical three dimensional Henon map is represented by first order difference equations. Extending the concept of continuous time fractional calculus to discrete case, we use fractional order difference equations to describe the existing discrete chaotic maps. This gives a wide variety of chaotic patterns with variation in order of difference equations which is now a real number. The chaotic behavior of the three dimensional Henon map is ascertained by using bifurcation diagrams and chaotic attractors. Further, a control strategy is proposed to stabilize the system which will suppress chaos. The proposed control strategy is based on active control approach. The simulation results presented at the end confirms the validity of the proposed technique.

A wideband high gain dielectric resonator antenna for RF energy harvesting application

Abstract: A novel high gain and broadband hybrid dielectric resonator antenna (DRA) is designed and experimentally validated To obtain the wide impedance bandwidth, the proposed antenna geometry combines the dielectric resonator antenna and an underlying slot with a narrow rectangular notch, which effectively broadens the impedance bandwidth by merging the resonances of the slot and DRA An inverted T-shaped feed line is used to excite both antennas, simultaneously It supports amalgamation of different resonant modes of the both, DRA and slot antenna The measured results show that the proposed antenna offers an impedance bandwidth of 120% from 167 to 67 GHz The antenna gain is next enhanced by a reflector placed below the antenna at an optimum distance On engineering the height and dimension of this reflector the antenna gain is improved from 22 dBi to 87 dBi at 17 GHz Finally, antenna operation is attested experimentally with a rectifier circuit in the frequency range of 18–36 GHz, where various strong radio signals are freely available for RF energy harvesting The measured maximum efficiency of the rectifier and rectenna circuit were found to be 744% and 614%, respectively

A new wideband planar antenna with band-notch functionality at GPS, Bluetooth and WiFi bands for integration in portable wireless systems

Abstract: Empirical results are presented for a novel miniature planar antenna that operates over a wide bandwidth (500 MHz to 3.05G Hz). The antenna consists of dual-square radiating patches separated by two narrow vertical stubs to reject interferences from GPS, Bluetooth and WiFi bands. Radiating patches and stubs are surrounded by a ground-plane conductor, and the antenna is fed through a common coplanar waveguide transmission line (CPW-TL). The two vertical stubs generate pass-band resonances enabling wideband operation across the following communications standards: cellular, APMS, JCDMA, GSM, DCS, PCS, KPCS, IMT-2000, WCDMA, UMTS and WiMAX. Embedded in the ground-plane conductor is an H-shaped dielectric slit, which has been rotated by 90°, whose function is to reject interferences from GPS, Bluetooth and WiFi bands. Measurements results confirm the antenna exhibits notched characteristics at frequency bands of GPS (1574.4–1576.4 MHz), Bluetooth (2402–2480 MHz) and WiFi (2412–2483.5 MHz). The impedance bandwidth of the antenna is 2.55G Hz for VSWR 3 .

Compact microstrip fractal Koch slot antenna with ELC coupling load for triple band application

Abstract: In this paper a novel triple band compact microstrip slot antenna is designed, utilizing fractal Koch shape based on metamaterial electric-LC element coupling load. The antenna is fed by CPW line, and it has triple band resonances operating at frequencies of about 1.5, 3.5 and 5.4 GHz for GPS, WiMAX and WLAN applications. The bandwidth of antenna at aforementioned frequencies is about 1.9%, 14% and 5% with the gains of −4.5, 3.75 and 5.3 dBi respectively. Also it has property of circular polarization for WiMAX application at 3.5 GHz. Furthermore metamaterial ELC element based on the metasurface theory, and making variation of the current distribution for circular polarization, made a compact small antenna at 1.5 GHz, where the antenna size is reduced to λ/5 × λ/5 through coupling on ELC element. The total size of the fractal antenna is assumed 40 × 40 mm, and is designed and fabricated on FR-4. The simulation results are extracted by HFSS commercial software, and compared with experimental results.