Search

In this paper, we are presenting a new metamaterial unit cell for satellite applications. The unit cell of the metamaterial was designed on FR-4 substrate material. The transmission characteristics of the unit cell display resonance at the frequency of 3.45 GHz of S-band of microwave region, which is usually suited for satellite communications. We did further analysis on the material’s effective medium properties by replacing the substrate material with Rogers RT 6010, lossy polyimide and aluminum nitride substrate materials, and we achieved different promising electromagnetic properties including double negative characteristics within the same band as well. For all these analyses, the popular “CST Microwave Studio” simulation software was adopted. The proposed design gives fine controllability in different types of metamaterial just by changing the substrate material, and all are working in the same S-band microwave spectrum.

In this paper, a miniature negative index meta-atom was designed; simulated, fabricated and measured based on parallel incidence of electromagnetic wave that can maintain a tri-band applications in microwave spectra. Compare to the other multi-band conventional metamaterial, the proposed meta-atom structure allows miniaturization factor and follows better effective medium ratio (EMR). Finite-integration technique (FIT) based computer simulation technology (CST) electromagnetic simulator was adopted to examine the design of the meta-atom. It exhibits tri-band response in conjunction with backward wave property over a certain frequency band in the microwave regime. Furthermore, the effective medium ratio is considerably improved compared to previously reported metamaterial. Moreover, few parametric analyses were done with the meta-atom. The size, scattering parameters and effective medium parameters of the proposed negative index miniaturized meta-atom is appropriate for tri-band applications.

In this article, a compact complementary split ring resonator (CSRR) based double-negative (DNG) metamaterial antenna is presented for wideband (4.49 GHz–21.85 GHz) wireless application. The antenna is incorporated with a DNG metamaterial patch: 50Ω microstrip feed line and partial ground plane. The antenna shows measured fractional bandwidth of 131.81% with a compact size of 0.37λ×0.37λ×0.01λ. The commercially available finite integration technique (FIT)-based simulation software, computer simulation technology (CST) microwave studio was adopted to investigate the performance of the proposed antenna. Several parametric studies were performed to investigate the effect of key structural parameters on antenna performances. The double-negative characteristics of the metamaterial were investigated as well.

A microstrip line-fed monopole antenna is proposed for super wideband (SWB) applications printed on an epoxy-resin-reinforced woven-glass material. The reported SWB antenna has been made of a rectangular partial ground plane with an L-type slit and a heart-shaped radiating patch. This antenna is connected precisely by a tapered feed line that provides SWB greater than ultra-wideband. The heart-shaped radiating patch and the partial ground plane containing a gap and an L-type slit on ground plane also play paramount roles to procure wide impedance bandwidth. It is determined from measurements that this antenna contains SWB characteristic [voltage standing wave ratio (VSWR) ≤2] spanning from 1.30 to 40 GHz (187.41%), with a bandwidth dimension ratio (BDR) of 5544.66 and a ratio bandwidth of 30.77:1. Simple construction, sharp surface current flow, much impedance bandwidth, nearly omnidirectional radiation patterns, stable peak gain (2.20–6.06 dBi), time domain performance, and considerable BDR (5544.66) make it a promising candidate for SWB applications.

This paper presents the design and analysis of a novel biaxial double-negative (DNG) metamaterial for electromagnetic cloaking operation in the microwave range. The proposed metamaterial exhibits DNG characteristics for the three axes (x, y, and z axes) wave propagation through the material. For the z-axis wave propagation, it shows resonance in the X-band and shows DNG characteristics there. Similarly, for the x-axis wave propagation, the material displays resonances in the multi-band (S-, C-, and X-bands) microwave frequency ranges with DNG characteristics at the S-, C-, and X-bands. The material exhibits DNG properties at the S- and C-bands for y-axis wave propagation as well. In the basic design, a new metamaterial structure was developed that was split into two arms. The commercially available finite-difference time-domain (FDTD)-based computer simulation technology (CST) Microwave Studio software was adopted to obtain the reflection and transmission parameters of the unit cell. The metamaterial was then used in designing a rectangular electromagnetic cloaking device where a metal cylinder was perfectly cloaked in the C-band region of the microwave spectra. The metamaterial shows near-zero refractive-index property as well in the cloaked zone. This is a novel and promising design in the electromagnetic paradigm for its biaxial DNG characteristics and rectangular cloaking operation.

A compact ultra-wideband (UWB) antenna is presented in this paper with a partial ground plane on epoxy woven glass material. The study is discussed to comprehend the effects of various design parameters with explicit parametric analyses. The overall antenna dimension is 0.22×0.26×0.016 λ. A prototype is made on epoxide woven glass fabric dielectric material of 1.6 mm thickness. The measured results point out that the reported antenna belongs to a wide bandwidth comprehending from 3 GHz to more than 11 GHz with VSWR

The design and absorption analysis of a unit cell of a new multiband split-S-shaped metamaterial is presented in this paper. The computer simulation technology (CST) software based on finite-difference time-domain method was used for the design of the unit cell and its S-parameter calculations. The proposed design shows the resonance frequency within the S-band, X-band, and Ku-band of the microwave spectra. In addition, the proposed material can be used in ε-negative, μ-negative, near-zero refractive index, and double-negative applications as well. The measured result is presented, which shows good conformity with the simulated result. The material shows nearly the same characteristics with bit shifted transmittance at the higher frequency side after reducing the coupling capacitance in the y- or z-axis of the proposed metamaterial. Moreover, it is evident from the investigation that, for shifting the lower ring in the z-axis, 15% more absorption can be achieved for the proposed metamaterial. The simple design, multipurpose applications, and compact size have made the design novel in the electromagnetic paradigm.

This paper presents a simple design analysis and performance evaluation of rectangular, slotted, microstrip feed patch antenna. The design processes are performed by employing the finite element method (FEM)-based commercial EM simulation software High-Frequency Structural Simulator (HFSS). The proposed multiband antenna is composed of a rectangular, slotted radiator formed with four arc slots and central square slot, reduced ground plane, and microstrip line for feeding. The patch antenna is excited through the standard 50 Ω RF transmission line, impedance-compliant SMA connector that is connected to the microstrip line. The optimal parametric dimensions from the numerical simulations are used for constructing the physical prototype on a custom-made, ceramic-filled biopolymer substrate of εr=10.0. Based on simulation results, the experimental data are collected, analyzed, and compared; the surface current distributions on the patch, gain, and radiation patterns are critically discussed. The measured results show the impedance bandwidths for S11 less than -10 dB are 712 MHz at 0.788 GHz band, 1.38 GHz at 3.34 GHz band, and 2.46 GHz at 8.01 GHz band. The good radiation pattern performances, almost stable gain over the bands, and appreciable bandwidths recommend the antenna for operating in RFID, WiMAX, and C/X-band applications.

The aim of this study was to consider a possible discrepancy in electromagnetic (EM) absorption in the human head. The finite-difference time-domain (FDTD) method with the lossy Drude model was adopted in this study. Here, the permittivity and conductivity of all head tissues were increased from 10% to 20% except when not using the same exposure conditions. Recognizable mobile phone frequencies of 1800 and 2450 MHz were studied in this simulation. The increase of up to 20% in conductivity and permittivity and varied substrate material always caused an EM absorption variation of 32.59% for specific absorption rate (SAR) 1 g and 35.25% for SAR 10 g at 1800 MHz, and variation of 20.37% for SAR 1 g and 17.99% for SAR 10 g at 2450 MHz, respectively.

In this paper, Modified-Dynamic Resource Allocation Management Algorithm is implemented in macrocell network. Previously, the algorithm was developed for heterogeneous network with both smallcell and macrocell network. The increasing number of network nodes in wireless cellular communication has increased the demand of proper resource allocation in heterogeneous network. Inter-cell interference is still considered as one of the most challenging issues in vast deployment of mobile base stations in urban and sub-urban areas. In LTE and LTE-A network, spectrum sharing and leasing mandated by huge number of base stations (indoor and outdoor) deployed, has an adverse effect on systems throughput and quality of service. Advances in resource management strategies has improved the interference scenarios in vast scale. A modified dynamic resource allocation management algorithm for macrocell network is proposed here to counter the intercell interference. Simulation environment is developed to study the performance of M-DRAMA for the marcoell network. The performance analysis shows that higher number of users get quality coverage at high node density.

In this paper we propose a new metamaterial unit cell structure on FR-4 substrate material that shows resonance in the microwave S-Band frequency range and also shows negative permittivity at that frequency. The material shows better performances with two resonances and Double Negative characteristics if Rogers RT 6010 substrate material is used. In this design two separate split ring resonators is used. We have used the CST Microwave Studio simulation software to get the reflection and transmission parameters for this unit cell.

In this paper, the specific absorption rate (SAR) reduction in human head with metamaterial attachment is calculated. The finite-difference time-domain (FDTD) method has been used to evaluate the SAR in an anatomically correct model of the human head. We designed the double-negative metamaterials by placing periodic array arrangement of split ring resonators (SRRs). By properly designing and tuning the structural parameters of SRRS, the effective medium parameters can be made negative at 900 and 1800 MHz band, as presented in this paper. Experimental results show that, with presence of resonators, SAR reduction in the human head is achievable. These results can provide useful insight into the design of safety-compliant mobile communication equipment.

The design of a printed compact planar antenna of asymmetrical structure with ultra wide bandwidth is described and investigated in this paper. The antenna provides more than 114% impedance bandwidth below VSWR 2 (from 3.3 to more than 12 GHz) with a center frequency of 7.65 GHz; thus it covers the bandwidth requirement for portable UWB wireless device applications. The structure of the asymmetric proposed antenna is very simple and composed of a small hexagonal shaped patch with two asymmetrical coplanar ground planes. It occupies an area of only 20 × 24.5 mm2 when printed on one side of an FR4 substrate with a thickness of 1.6 mm.

The aim of this paper is to analyze the effects of electromagnetic (EM) energy absorption at 900 and 1900 MHz when the human head’s dielectric properties are varied. This radiation is measured in terms of specific absorption rate (SAR). The characteristics of the helical antenna and its substrates with variation of the human head dielectric properties were simulated via the finite-difference time domain (FDTD) method using the CST Microwave studio. The human head dielectric properties are manipulated by increasing and decreasing 10% and 20% of each dielectric property. In this study, SAR values increase with increase of the human head’s conductivity, while increase of permittivity and densities decreases it. A helical antenna with a substrate of FR4 resulted in higher SAR values in all frequencies. The head SAR values are higher in the upper frequency exposures. The helical antenna with a substrate of Rogers RO3006 (loss free) was found to be the best-tested substrate, which contributed toward much lower SAR values in all GSM frequency bands.