The Surface Current and Charge Density Induced on Finite Cylinder Mounted Near a Perfectly Conducting Ground Plane.

1978 ◽  
Author(s):  
E. D. Greer ◽  
W. D. Burnside
Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Navneet Sharma ◽  
Anubhav Kumar ◽  
Asok De ◽  
Rakesh K. Jain

Abstract A compact, circularly polarized, CPW-fed antenna is proposed for wearable applications in ISM Band (5.8 GHz). The antenna is based on DGS, where the ground plane is responsible for impedance matching. The 10 dB impedance of the proposed antenna varies from 5.39 GHz to 5.94 GHz. The circular stub introduced in the ground plane mitigates the surface current and enriches the 3 dB axial ratio from 5.73 GHz to 5.92 GHz. Proposed antenna exhibits the LHCP and RHCP pattern of circular polarization, the antenna can effectively work for biomedical and wearable applications. The antenna is analyzed on the skin phantom model and the SAR value obtained is 1.218 W/kg, which is below the maximum permissible level. The proposed antenna is also used for the detection of breast tumors.


Author(s):  
Ajay Thatere ◽  
◽  
Sachin Khade ◽  
Vipul Lande S ◽  
◽  
...  

A modified rectangular Microstrip slot antenna for numerous applications like WLAN, Wi-Fi 5, satellite telecommunication and 5G application is portrayed. The proposed antenna has dimension of 25×30×1.6 mm3. The structure consists of partial ground and DGS. The proposed design is embedded on FR4 lossy substrate having dielectric constant of 4.3 and thickness of 1.6 mm. Two similar inverted L shape CLLR are introduced at left and right edge of the ground plane to improve current distribution and to achieve wide bandwidth. The results like reflection coefficient, surface current, gain, directivity, VSWR, impedance and radiation pattern are found up to the mark.


2021 ◽  
Vol 8 ◽  
Author(s):  
Liansheng Wang ◽  
Dongyan Xia ◽  
Quanhong Fu ◽  
Xueyong Ding ◽  
Yuan Wang

In this paper, we report a switchable ultra-wideband metamaterial absorber with polarization-insensitivity and wide-incident angle at THz band which is composed of VO2 disk, polyimide dielectric substrate, and gold ground plane. The results show that the absorption is greater than 90% from 3.5–8 THz for a temperature of 300 K and this absorption band disappears when the temperature rises to 350 K. The absorption property of our proposed metamaterial absorber is insensitive to polarization states and angles and it can withhold high absorption of more than 80% for wide-incident angles, up to 60° for TE mode and TM mode. The wideband absorption mechanism is elucidated using an effective medium and surface current analysis.


Circuit World ◽  
2020 ◽  
Vol 46 (4) ◽  
pp. 281-284
Author(s):  
Elakkiya A. ◽  
Radha Sankararajan ◽  
Sreeja B.S. ◽  
Manikandan E.

Purpose A novel and simple six-band metamaterial absorber is proposed in the terahertz region, which is composed of an I-shaped absorber and circular ring with four gaps and a continuous metal ground plane separated by only 0.125 mm polyimide dielectric substrate. Initially, I-shaped resonator gives three bands at 0.4, 0.468 and 0.4928 THz with the absorptivity of 99.3%, 97.9% and 99.1%, respectively. The purpose of this paper is to improve the number of bands, for which the authors added the circular ring with four gaps, so the simulated metamaterial absorber exhibited six absorption peaks at 0.3392, 0.3528, 0.3968, 0.4676, 0.4768 and 0.492 THz, with the absorption rate of 91.4%, 94.2%, 94.9%, 90.3%, 77.5% and 97.4%, respectively. The surface current distribution and angle independence are explained for all the six frequencies which are used to analyze the absorption mechanism clearly. Structure maximum uses the squares and circles, so it will make the fabrication easy. The multiband absorbers obtained here have potential applications in many engineering technology, thermal radiation, material detection and imaging and optoelectronic areas. Design/methodology/approach This paper presents the design of the six-band metamaterial absorber which is from the I-shaped resonator and circular ring with four gaps and the metallic ground plane separated by the 0.125 polyimide dielectric substrate. The absorber exhibited six absorption peaks at 0.3392, 0.3528, 0.3968, 0.4676, 0.4768 and 0.492 THz, with the absorption rate of 91.4%, 94.2%, 94.9%, 90.3%, 77.5% and 97.4%, respectively. From the fabrication point of view, the proposed six-band metamaterial absorber has a very simple geometrical structure, and it is very easy to be fabricated. Findings The authors present a new and simple design of six-band absorber based on an I-shaped absorber and circular ring with four gaps and a metallic ground plane separated by a polyimide layer having the thickness of 0.125 mm. Six different resonance absorption peaks are found at 0.3392, 0.3528, 0.3968, 0.4676 , 0.4768 and 0.492 THz. Surface current distribution and angle independence plot have been studied to understand the absorption behavior of the designed terahertz metamaterial absorber. Originality/value The multiband absorbers obtained here have potential applications in many engineering technology, thermal radiation, material detection, security, sensors, imaging and optoelectronic areas.


Author(s):  
David Sumner ◽  
He Li

The mean wake of two identical surface-mounted finite-height circular cylinders arranged in a tandem configuration was investigated in a low-speed wind tunnel using a seven-hole pressure probe. The Reynolds number was Re = 2.4×104, the cylinder aspect ratio was AR = 9, and the boundary layer thickness on the ground plane relative to the cylinder height was δ/H ≈ 0.4. Three centre-to-centre longitudinal pitch ratios of L/D = 1.125, 2, and 5 were examined, corresponding to the extended-body, reattachment, and co-shedding flow regimes, respectively. Reference measurements were also made in the wake of a single finite circular cylinder of AR = 9. For the tandem configurations, velocity measurements were made behind the downstream cylinder in two orthogonal vertical planes. Compared to the wake of the single surface-mounted finite-height circular cylinder, the mean downwash and upwash flows for the tandem cylinders, behind the downstream cylinder, were weaker, the mean recirculation zone behind the downstream cylinder was shorter, and the mean wake extended higher above the ground plane, for all three pitch ratios. Marked changes were also observed in the mean streamwise wake vortex structures, compared to the case of the single finite cylinder. For the extended-body and reattachment flow regimes, the tip vortex structures became elongated in the wall-normal direction. In the co-shedding regime, two sets of tip vortices were observed, with the second set possibly originating from the upstream cylinder.


2015 ◽  
Vol 735 ◽  
pp. 273-277 ◽  
Author(s):  
Raimi Dewan ◽  
M.K.A. Rahim ◽  
Mohamad Rijal Hamid ◽  
M.F.M. Yusoff

A Coplanar Waveguide (CPW) wideband antenna operates from 2.69 GH to 6.27 GHz which act as reference antenna (RA) has been designed. A Dual Band AMC (DBAMC) unit cells have been proposed to operate at 2.45 GHz and 5.8 GHz. AMC is a metamaterial which mimics the behavior of zero reflection phase of Perfect Magnetic Conductor (PMC) at resonance frequency which not naturally existed in nature. Subsequently the antenna is incorporated with AMC unit cell, herein referred as Antenna with Dual Band AMC (ADBAMC). The DBAMC succesfully excites additional resonance at 2.45 GHz outside the initial operating range of standalone CPW wideband antenna. Incorporation of DBAMC to antenna achieves back lobe suppression at 2.45 GHz and 5.8 GHz. The overall average gain of AMC incorporated antenna is improved from 2.69 to 6.29 GHz as opposed to the standalone reference CPW wideband antenna. Study of surface current is also presented and discussed.


2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Qiang Wang ◽  
Yan Zhang

A new compact ultra-wideband (UWB) antenna with triband-notched characteristics is presented. The structure of the proposed antenna is simple and symmetric. A modified ground is introduced to obtain a wide impedance bandwidth of 2.9–13.4 GHz withS11<-10 dB. By inserting two arc-shaped slots in the radiation patch, two sharp bands of 3.3–3.7 GHz and 5.15–5.35 GHz are notched. The notch band of 7.25–7.75 GHz is achieved by etching a U-shaped slot in the ground plane. The notched bands can be controlled, respectively, while the characteristics of the proposed UWB antenna almost keep completely unchanged at the unnotched frequencies. Equivalent circuit models, surface current distributions, and input impedance are applied to analyze the principle of the proposed UWB antenna. Parametric studies are given. Simulated and measured results show that the proposed antenna has good impedance matching, stable radiation patterns, and constant gain.


Author(s):  
Muhammad Khalid ◽  
Kamran Raza

This paper presents novel reduced size diagonal slot embedded Triangular Gasket fractal patch antenna for multiband wireless applications. The diagonal slot geometry is embedded in triangular patch antenna for initial size reduction of the basic cell and further miniaturization is achieved by fractalization of the cell upto third order. Three frequency resonances of 2.4, 6.5 and 9.23 GHz are optimized for WiFi, WiMAX and WLAN (Wireless Local Area Network) applications in the S, C and X frequency bands. Size reduction upto 55.32 and 80.74% is achieved in terms of whole antenna area and copper cladding remaining respectively in comparison to triangular patch antenna. Antenna 3D (Three-Dimensional) modeling, simulation and optimization for the desired BW (Bandwidth) and gain requirements are done in HFSS (High Frequency Structure Simulator) and CST (Computer Simulation Technology). Effects of embedding diagonal slot in the basic triangular cell is analyzed in terms of the diagonal slot length and width with corresponding frequency response variations. Microstrip feed line dimensions and ground plane separation from the radiating top layer is optimized for achieving acceptable BWs less than -10 dB for the desired multiple resonances. E-field, H-field, current density and surface current plots are presented to verify the radiations for multiband wireless applications. Proposed slot embedded fractal radiator is fabricated and measured frequency responses and gain patterns are demonstrated in comparison with simulated results for verification of the concept.


2020 ◽  
Vol 9 (1) ◽  
pp. 59-64
Author(s):  
B. Ait Ahmed ◽  
A. Naghar ◽  
O. Aghzout ◽  
A. Vazquez Alejos ◽  
F. Falcone

This paper presents a compact C-band bandpass filter with improved out-of-band rejection. It consists of a symmetric three-pole parallel coupled line microstrip loaded with complementary split ring resonators (CSRRs) and slot resonators. Enhancements regarding the filter responses are obtained by etching these two parasitic shapes successively. When, CSRRs are introduced in the ground plane, exactly in the back of the transmission line of 50 -Ohms , improvements on the filter selectivity level are achieved. Whereas, the slot resonator elements are implemented on the feed line to permit the suppression of the second harmonics. To reduce the second harmonics of 11:1-13GHz, the parasitic elements are both combined, widen the filter rejection of 5:81%. The surface current distribution together with the equivalent circuit are also studied in order to demonstrate the slots and the CSRRs effect parameters on the behavior of the proposed filter. A prototype of the optimal filter is fabricated and measured.Theory and experiment results prove the validity of the new design procedure.


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