Advanced Electromagnetics (E-Journal)
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Tri-band MIMO Antenna for WLAN, WiMAX and Defence System & Radio Astronomy Applications
No full textIn this paper, an efficacious and impermeable undeviating MIMO consist of 70 x 50 x 0.4 mm3 is used for WLAN, defence system & radio astronomy and WiMAX applications. To keep in order abandoning the reactive connection between the antennas, a neutralizing line is connected between the two symmetrical radiating elements. Another technique to reducing isolation (mutual coupling) between the antennas, four small slits of small size are etched onto to the ground plane. This has resulted in the proposed antenna giving a good bandwidth at the three resonant frequencies of (3.2–3.7 GHz) for Wireless LAN, (5.1–5.6 GHz) WiMAX and (6.7–7.5 GHz) defence system & radio astronomy applications with |S11|< -10 dB and mutual coupling |S12|< -20 dB for the entire operating band. The simulation results and measured results demonstrate that tri-band MIMO antenna is more acceptable for the design in portable device applications
UHF RFID Tag Based on Modified Dihedral Corner for Enhanced Read Range and Broadband Operation
No full textThis paper presents the design and development of a novel UHF RFID tag which exhibits enhanced read range over the entire UHF RFID band of 860-930MHz. This novel UHF RFID tag consists of an antenna based on modified dihedral corner with an embedded double T-match and a Murata LXMS 31ACNA010 chip attached to the terminals of the antenna. Measured read range variations over the azimuth and elevation angular ranges show enhanced read range over wide angular ranges as compared to conventional RFID tags
Theoretical and Experimental Study of Split Semi Horse Shoe Structure
No full textIn this paper a new planar metamaterial structure that looks like semi-horse shoe in shape (SSHSS) is designed and simulated. Theoretical analysis of proposed structure done using equivalent circuit theory. Medium effective parameters are extracted using modified NRW approach which proved the metamaterial property of the new unit cell. Radiation pattern, directivity and gain of the new structure were illustrated which gives the possibility of using SSHSS as the antenna. Proposed structure shows multiband characteristics. This antenna shows high directivity (7.92 dBi, 7.86 dBi, 10.11 dBi) and moderate gain (2.55 dBi, 3.90 dBi, 5.07 dBi) at 5.83 GHz, 8.41 GHz, 10.68 GHz respectively. RT duroid is used for fabrication of prototype of the proposed structure. This new structure can be used as metamaterial inspired antenna as well as normal patch antenna. Experimental results shows good agreement with simulated and theoretical results.The proposed structure has been simulated using IE3D electromagnetic simulator
Effect of Substrate Scaling on Microstrip Patch Antenna Performance
No full textThe Maxwell field equations (MFEs), as ecumenical model of electromagnetic phenomena, are scale-invariant under Lorentz Transformation (LT). To apply LT, some considerations are required which are not all practically available or technologically attainable; hence, the scale-invariant feature may not be reached effectively. Paving the way to focus on this issue, the effect of substrate thickness scaling as an uncontrollable parameter, is explored on eight identical patch antennas with different substrate thicknesses. In this way, the resonant frequency and complex value of return loss are measured. The effect of manufacturing tolerances of dielectric thickness on resonant frequency deviation and return loss magnitude are carefully studied, too. Also the unwanted distortive effect of selected electrical connection, say as a female SMA connector, is investigated at higher frequencies. The obtained results are comparatively analyzed which confirm the practical bottlenecks in meeting the antenna parameters scaling
Multiband and Miniaturized dual layer Antenna incorporated with FSS and DGS
No full textA novel dual layer rectangular printed Antenna based on loop type Frequency selective surfaces with five concentric rings and I shaped defected ground structure (DGS) is designed and investigated. The deigned antenna is tested for application in C band, WiFi devices and some cordless telephones and X band radiolocation, airborne and naval radars as multiband operational frequencies are at 5.5GHz, 6.81GHz, 9.3GHz and thus covers two wireless communication band C Band (4 to 8GHz ) and X band (8 to 12 GHz) The bandwidth is 200MHz, 300MHz and 1GHz respectively and measured gain of this designed antenna are 2.42dBi against 5.5GHz, 2.80dBi against 6.81GHz, 6.76dBi against 9.3GHz. The proposed antenna in addition to multiband operation also exhibits minituarization.The Floquet port technique is used to analyse concentric rings. The Results comparison of proposed structure with the basic dual layer antenna resonaing at 5.5GHz shows the patch area is reduced by 58.15% while the volume of the antenna is reduced by 81.5%. 
THz Generation using Nonlinear Optics: Mathematical Analysis and Design of THz antennas
No full textIn this paper, a mathematical model is designed for THz generation from a nonlinear random medium. Using nonlinear optics and Maxwell’s equations a set of nonlinear wave equations are derived to give scattered electromagnetic fields from an inhomogeneous medium. First, the analysis is done with second order nonlinearity. Its scattering parameters are calculated for THz radiation. Secondly, third order nonlinearity is described in terms of the coupling of Scalar and vector field components of nonlinear wave equations. The coupling of waves results in soliton generation. Multiple nonlinear interaction in the medium also gives wide bandwidth. Speed and high bandwidth is a demand of future networks. Hence a mathematical proof is implemented for THz antennas using SHG (Second harmonic generation) and THG (Third harmonic generation) materials. These antennas are designed and simulated using GaAs as a SHG material, and Graphene with SiO2 substrate as a THG material. GaAs is used as a substrate, which radiates at 524.8 GHz giving a high bandwidth of 25 GHz. Similarly, Graphene patch antenna with SiO2 substrate radiates in THz region at 3.5THz giving very high bandwidth of 2.5THz
Compact Reconfigurable Band Notched UWB Cylindrical Dielectric Resonator Antenna Using Single Varactor Diode
No full textThis paper presents compact UWB cylindrical dielectric resonator antenna with reconfigurable band notch capability using single varactor diode. Theoretical results are achieved for the design with the range of frequencies 4-10.6 GHz. Using single varactor diode, different notch frequencies can be obtained using different capacitance values. The effect of changing the varactor position is also examined. A Wide range of notch frequencies can be achieved using this simple configuration, which covers most of coexisted narrow band systems. The notch frequency can be lower by increasing the capacitance value. Finite Element Method (FEM) and Finite Integration Technique (FIT) are hired to simulate the proposed antenna structure using HFSS and CST MWS respectively. The notch frequency covers the WLAN band when C=0.9 pF and covers the WiMAX band when the capacitance is changed to 0.8 pF for the same antenna configuration and varactor position. The antenna with DRA has a directive radiation pattern in E-plane and omnidirectional pattern in H-plane. Also, the gain is suppressed in the notched frequency. The group delay is nearly stable in the UWB frequency range, except at the notch frequencies
Performance Analysis of Different Indoor Ultra Wide Band Channel Indicators
No full textIn this paper, performance of different indicators for the profiling of Ultra Wide Band (UWB) wireless propagation channel are analyzed. In particular, the γ-indicator and the kurtosis index k are compared in terms of the standard error. In order to improve the accuracy in the kurtosis case, results of the bootstrap error procedure are also accomplished. Further, an evaluation on the computational time needed for error estimation, is also provided. The comparison is made according to a real set of data derived from UWB measurement campaign accomplished within a modern laboratory/office building in which the two above mentioned indicators have been evaluated
Review on the Design of the Isolation Techniques for UWB-MIMO Antennas
No full textUltra wide band - Multiple Input Multiple Output antenna technology provides higher data rates and the combination of the ultra wide band (UWB) and the multiple input multiple output (MIMO) technologies provides a solution for the demand of still higher data rates i.e. in excess of 3 Gb/sec in the future. As the antenna technologies are improving, the size of the MIMO antenna is growing smaller and smaller. Placing the antenna elements in such close proximity increases the coupling between them. Various isolation techniques have to be introduced between the antenna elements to decrease the coupling and to improve the isolation. A study of the various isolation enhancement techniques have been made in this review. It analyses the various isolation enhancement methods such as using orthogonal polarization, parasitic elements, varied decoupling structures, defected ground structures (DGS), neutralization line (NL) and finally by using metamaterials. Metamaterials is a technology to perk up the isolation between the antenna elements. Split ring resonator (SRR) behaves as a metamaterial and it is used as an isolation mechanism in this study. The antennas are simulated and the results are compared. The method using parasitic elements gives the highest isolation of 35 dB and it is 5 dB better than the methods using orthogonal polarization and using the decoupling structure. The performance of all the antennas satisfies the conditions for minimum isolation. The envelope correlation coefficient is nearly zero in all the antennas and it implies good diversity performance. The diversity gain is also calculated for the various antennas and it satisfies good diversity performance. The bandwidth of the antennas is in the UWB frequency range and they have a fractional bandwidth above the required value of 1.09. The capacity loss for all the antennas is very low and the antennas using defected ground structure and the decoupling structure gives very low capacity loss
A Multiband Slot Antenna loaded with Stubs for WLAN/WiMAX/Satellite TV Applications
No full textA compact planar multiband antenna operating at 2.65 (lower WiMAX)/5.20 (WLAN)/6.75/7.30 GHz (Satellite TV) is presented. The antenna consists of circular radiator in which a rectangular slot is etched out. Also, the circular radiator is loaded with a rectangular and two hook-shaped stubs to achieve multiband operations. The impedance matching at these bands is achieved by using two small square stubs placed inside the hook-shaped stubs. The antenna has an electrical dimension of 0.17λl x 0.17λl x 0.01λl at the lower frequency of 2.65 GHz. The antenna has S11<-10dB bandwidth of 3% (2.6-2.68GHz), 2.3% (5.12-5.24GHz), 1.2% (6.68-6.76GHz) and 1.37% (7.26-7.36GHz) in simulation and about 6.25% (2.48-2.64GHz), 2.24% (5.3-5.42GHz), 1.15% (6.92-7.00GHz) and 1.1% (8.04-8.12GHz) under measurement. The entire simulation analysis of the antenna is carried out using HFSS v.13.0