scholarly journals A Compact Four-Port Coplanar Antenna Based on an Excitation Switching Reconfigurable Mechanism for Cognitive Radio Applications

2019 ◽  
Vol 9 (15) ◽  
pp. 3157 ◽  
Author(s):  
O ◽  
Jin ◽  
Choi
Keyword(s):  
Cognitive Radio ◽  
High Frequency ◽  
Coplanar Waveguide ◽  
Low Frequency ◽  
Loop Antenna ◽  
Ultra Wideband ◽  
Frequency Range ◽  
Uwb Antenna ◽  
High Isolation ◽  
Loop Antennas

In this paper, we propose a compact four-port coplanar antenna for cognitive radio applications. The proposed antenna consists of a coplanar waveguide (CPW)-fed ultra-wideband (UWB) antenna and three inner rectangular loop antennas. The dimensions of the proposed antenna are 42 mm × 50 mm × 0.8 mm. The UWB antenna is used for spectrum sensing and fully covers the UWB spectrum of 3.1–10.6 GHz. The three loop antennas cover the UWB frequency band partially for communication purposes. The first loop antenna for the low frequency range operates from 2.96 GHz to 5.38 GHz. The second loop antenna is in charge of the mid band from 5.31 GHz to 8.62 GHz. The third antenna operates from 8.48 GHz to 11.02 GHz, which is the high-frequency range. A high isolation level (greater than 17.3 dB) is realized among the UWB antenna and three loop antennas without applying any additional decoupling structures. The realized gains of the UWB antenna and three loop antennas are greater than 2.7 dBi and 1.38 dBi, respectively.

scholarly journals Characteristics UWB Planar Antenna with dual notched bands for WIMAX and WLAN

2018 ◽  
Vol 7 (5) ◽  
pp. 20-25
Author(s):  
M. Debab ◽  
Z. Mahdjoub
Keyword(s):  
Frequency Band ◽  
Loss Tangent ◽  
High Frequency ◽  
Coplanar Waveguide ◽  
Ultra Wideband ◽  
Planar Antenna ◽  
Network Analyzer ◽  
Uwb Antenna ◽  
Quarter Wavelength ◽  
Novel Design

In this article, a novel design of ultra wideband monopole antenna with dual notched bands performance is proposed. The size of the UWB antenna is minimized to 20 -17.6mm2 , printed on FR4 substrate 1.5 mm thickness and loss tangent tan𝛿 =0.02, and is fed by coplanar waveguide. The operation bandwidth of the designed antenna is from 3.1 GHz to more than 10 GHz. Band notches characteristics of antenna to reject the frequency band, WIMAX Band and WLAN Band, is realized by cutting three quarter wavelength slots in the radiating patch. A quarter wavelength slot in the radiator of the antenna is used to create a frequency band notch at the WIMAX frequency band. However, the WLAN frequency band is notched using two symmetrical quarter wavelength slots. The proposed antenna is simulated using HFSS and CST high frequency simulators. These results are compared with measured results by using network analyzer.

scholarly journals CPW-Fed Flexible Ultra-Wideband Antenna for IoT Applications

Micromachines ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 453
Author(s):  
Sharadindu Gopal Kirtania ◽  
Bachir Adham Younes ◽  
Abdul Rakib Hossain ◽  
Tutku Karacolak ◽  
Praveen Kumar Sekhar
Keyword(s):  
High Frequency ◽  
Return Loss ◽  
Coplanar Waveguide ◽  
Ultra Wideband ◽  
Impedance Bandwidth ◽  
Uwb Antenna ◽  
Radiation Characteristics ◽  
Antenna Structure ◽  
Iot Applications ◽  
Good Agreement

In this article, an inkjet-printed circular-shaped monopole ultra-wideband (UWB) antenna with an inside-cut feed structure was implemented on a flexible polyethylene terephthalate (PET) substrate. The coplanar waveguide (CPW)-fed antenna was designed using ANSYS high-frequency structural simulator (HFSS), which operates at 3.04–10.70 GHz and 15.18–18 GHz (upper Ku band) with a return loss < −10 dB and a VSWR < 2. The antenna, with the dimensions of 47 mm × 25 mm × 0.135 mm, exhibited omnidirectional radiation characteristics over the entire impedance bandwidth, with an average peak gain of 3.94 dBi. The simulated antenna structure was in good agreement with the experiment’s measured results under flat and bending conditions, making it conducive for flexible and wearable Internet of things (IoT) applications.

scholarly journals Design of a Miniaturized Rectangular Multiturn Loop Antenna for Shielding Effectiveness Measurement

Sensors ◽  
2020 ◽  
Vol 20 (11) ◽  
pp. 3178
Author(s):  
Sangwoon Youn ◽  
Tae Heung Lim ◽  
Eunjung Kang ◽  
Dae Heon Lee ◽  
Ki Baek Kim ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Loop Antenna ◽  
Shielding Effectiveness ◽  
Frequency Range ◽  
Ferrite Core ◽  
Very Low Frequency ◽  
Effectiveness Measurement ◽  
Antenna Factor ◽  
Plastic Case

This paper proposes a novel miniaturized rectangular loop antenna sensor consisting of a multiturn wire and a cuboid ferrite core. The lateral surface of the ferrite core is tightly wound by the multiturn wire. To verify its feasibility, the antenna sensor is fabricated, and the antenna factor (AF) levels are measured using the three-antenna method from the very low frequency (VLF) to the high-frequency (HF) bands. The measured AF levels are 31.8 dB (with a covering plastic case) and 33.1 dB (without a covering plastic case) at 30 kHz. In addition, the proposed antenna is employed in the shielding effectiveness measurement of a small commercial cabinet to observe its suitability for shielding effectiveness (SE) measurement of small shielding enclosures. The SE values averaged over the frequency range from 10 kHz to 3 MHz are 4.1 dB and 12 dB in the horizontal and vertical polarizations, respectively.

Evaluation of Special Hearing Aids for Deaf Children

1971 ◽  
Vol 36 (4) ◽  
pp. 527-537 ◽  
Author(s):  
Norman P. Erber
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Hearing Aid ◽  
Low Frequency ◽  
Acoustic Stimulation ◽  
Deaf Children ◽  
Frequency Range ◽  
Frequency Limit ◽  
Unpublished Studies ◽  
Published Research

Two types of special hearing aid have been developed recently to improve the reception of speech by profoundly deaf children. In a different way, each special system provides greater low-frequency acoustic stimulation to deaf ears than does a conventional hearing aid. One of the devices extends the low-frequency limit of amplification; the other shifts high-frequency energy to a lower frequency range. In general, previous evaluations of these special hearing aids have obtained inconsistent or inconclusive results. This paper reviews most of the published research on the use of special hearing aids by deaf children, summarizes several unpublished studies, and suggests a set of guidelines for future evaluations of special and conventional amplification systems.

scholarly journals An Improved Time Integration Method Based on Galerkin Weak Form with Controllable Numerical Dissipation

2021 ◽  
Vol 11 (4) ◽  
pp. 1932
Author(s):  
Weixuan Wang ◽  
Qinyan Xing ◽  
Qinghao Yang
Keyword(s):  
High Frequency ◽  
Integration Method ◽  
Time Integration ◽  
Low Frequency ◽  
Weak Form ◽  
High Accuracy ◽  
Numerical Dissipation ◽  
Frequency Range ◽  
Time Integration Method ◽  
Numerical Damping

Based on the newly proposed generalized Galerkin weak form (GGW) method, a two-step time integration method with controllable numerical dissipation is presented. In the first sub-step, the GGW method is used, and in the second sub-step, a new parameter is introduced by using the idea of a trapezoidal integral. According to the numerical analysis, it can be concluded that this method is unconditionally stable and its numerical damping is controllable with the change in introduced parameters. Compared with the GGW method, this two-step scheme avoids the fast numerical dissipation in a low-frequency range. To highlight the performance of the proposed method, some numerical problems are presented and illustrated which show that this method possesses superior accuracy, stability and efficiency compared with conventional trapezoidal rule, the Wilson method, and the Bathe method. High accuracy in a low-frequency range and controllable numerical dissipation in a high-frequency range are both the merits of the method.

scholarly journals Band notched self complementaryultra wideband antenna for wireless applications

2018 ◽  
Vol 7 (2.8) ◽  
pp. 529 ◽  
Author(s):  
Ch Ramakrishna ◽  
G A.E.Satish Kumar ◽  
P Chandra Sekhar Reddy
Keyword(s):  
High Frequency ◽  
Return Loss ◽  
Wide Band ◽  
Ultra Wideband ◽  
Impedance Bandwidth ◽  
Relative Dielectric Permittivity ◽  
Frequency Range ◽  
Ground Structure ◽  
Wireless Applications ◽  
Patch Edge

This paper presents a band notched WLAN self complementaryultra wide band antenna for wireless applications. The proposed antenna encounters a return loss (RL) less than -10dB for entire ultra wideband frequency range except band notched frequency. This paper proposes a hexagon shape patch, edge feeding, self complementary technique and defective ground structure. The antenna has an overall dimensionof 28.3mm × 40mm × 2mm, builton  substrate FR4 with a relative dielectric permittivity 4.4. And framework is simulated finite element method with help of high frequency structured simulator HFSSv17.2.the proposed antenna achieves a impedance bandwidth of 8.6GHz,  band rejected WLAN frequency range 5.6-6.5 GHz with  vswr is less than 2.

Electromagnetic Property of La0.7Sr0.3MnO3/Ag Composite at High Frequency

2015 ◽  
Vol 655 ◽  
pp. 182-185
Author(s):  
Ke Lan Yan ◽  
Run Hua Fan ◽  
Min Chen ◽  
Kai Sun ◽  
Xu Ai Wang ◽  
...  
Keyword(s):  
High Frequency ◽  
Single Phase ◽  
Low Frequency ◽  
Electromagnetic Property ◽  
High Frequency Range ◽  
Frequency Range ◽  
Free Electron Concentration ◽  
Theoretical Simulation ◽  
Electrical And Magnetic Properties ◽  
Three Phase

The phase structure, and electrical and magnetic properties of La0.7Sr0.3MnO3(LSMO)-xAg (xis the mole ratio,x=0, 0.3, 0.5) composite were investigated. It is found that the sample withx=0 is single phase; the samples withx=0.3 and 0.5 present three phase composite structure of the manganese oxide and Ag. With the increasing of Ag content, the grain size of the samples increases and the grain boundaries transition from fully faceted to partially faceted. The permittivity of spectrum (10 MHz - 1 GHz) and the theoretical simulation reveal that the plasma frequencyfpincrease with Ag content, due to the increasing of free electron concentration, which is further supported by the enhancement of conductivity. While for the permeability (μr'), theμr'decrease with the increasing of Ag content at low frequency range (f< 20 MHz), while at the relative high frequency range (f> 300 MHz), theμr'increased with Ag content. Therefore, the introduction of elemental Ag resulted in a higherμr'at the relative high frequency range.

Anderson-Stuart Model to Analyze AC and DC Conductivity of Lithium Zinc-Silicate Glass / Glass-Ceramics

2007 ◽  
Vol 280-283 ◽  
pp. 919-924
Author(s):  
M.S. Jogad ◽  
V.K. Shrikhande ◽  
A.H. Dyama ◽  
L.A. Udachan ◽  
Govind P. Kothiyal
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Low Frequency ◽  
Frequency Region ◽  
Dc Conductivity ◽  
Frequency Range ◽  
High Frequency Region ◽  
Dc Conductivities ◽  
Conductivity Variation ◽  
Different Temperatures

AC and DC conductivities have been measured by using the real (e¢) and imaginary (e¢¢) parts of the dielectric constant data of glass and glass-ceramics (GC) at different temperatures in the rage 297-642K and in the frequency range 100 Hz to 10 MHz. Using Anderson –Stuart model, we have calculated the activation energy, which is observed to be lower than that of the DC conductivity. The analysis for glass/glass-ceramics indicates that the conductivity variation with frequency exhibits an initial linear region followed by nonlinear region with a maximum in the high-frequency region. The observed frequency dependence of ionic conductivity has been analyzed within the extended Anderson–Stuart model considering both the electrostatic and elastic strain terms. In glass/glassceramic the calculations based on the Anderson-Stuart model agree with the experimental observations in the low frequency region but at higher frequencies there is departure from measured data.

Design and Analysis of Integrated Wilkinson Power Divider-Fed Conformal High-Gain UWB Array Antenna with Band Rejection Characteristics for WLAN Applications

2020 ◽  
pp. 2150133
Author(s):  
Soufian Lakrit ◽  
Hicham Medkour ◽  
Sudipta Das ◽  
B. T. P. Madhav ◽  
Wael A. E. Ali ◽  
...  
Keyword(s):  
Antenna Arrays ◽  
Local Area Network ◽  
Ultra Wideband ◽  
Bending Test ◽  
Power Divider ◽  
Area Network ◽  
Curved Surfaces ◽  
Uwb Antenna ◽  
High Isolation ◽  
Wilkinson Power Divider

Flexible ultra-wideband (UWB) antenna arrays with band notching characteristics are proposed in this work. A new wideband and high-isolation Wilkinson power divider (WPD) is designed to construct the feed systems of the UWB antenna arrays. The proposed WPD is achieved by introducing a significant modification to the conventional WPD and the new one is composed of four isolation stages. Multiple stages helped to achieve wideband from 2[Formula: see text]GHz to more than 12[Formula: see text]GHz with high isolation characteristics of more than 20[Formula: see text]dB and insertion losses around 3.3[Formula: see text]dB. The designed WPD is then applied to feed two UWB monopole antenna arrays which offer a notched band centered at 5.5[Formula: see text]GHz to reject interference from wireless local area network (WLAN) system and can be integrated with curved surfaces. To verify the performance of the proposed structure, two array configurations are practically fabricated and measured. The results show that both the arrays have UWB operational bandwidth (3.5–11.8[Formula: see text]GHz for [Formula: see text] array and 3.6–12[Formula: see text]GHz for [Formula: see text] array) that includes the UWB spectrum. Attractive agreement between simulation and measurement results is obtained. Furthermore, the bending test is carried out on the [Formula: see text] array showing the good performance of the proposed system when installed on curved surfaces for different bent angles.

Shallow subsurface mapping by electromagnetic sounding in the 300 kHz to 30 MHz range: Model studies and prototype system assessment

Geophysics ◽  
1994 ◽  
Vol 59 (8) ◽  
pp. 1201-1210 ◽  
Author(s):  
Duff C. Stewart ◽  
Walter L. Anderson ◽  
Thomas P. Grover ◽  
Victor F. Labson
Keyword(s):  
Dielectric Permittivity ◽  
High Frequency ◽  
Low Frequency ◽  
Computer Programs ◽  
Thin Layers ◽  
Depth Range ◽  
Frequency Range ◽  
Model Studies ◽  
New Instrument ◽  
Displacement Currents

A new instrument designed for frequency‐domain sounding in the depth range 0–10 m uses short coil spacings of 5 m or less and a frequency range of 300 kHz to 30 MHz. In this frequency range, both conduction currents (controlled by electrical conductivity) and displacement currents (controlled by dielectric permittivity) are important. Several surface electromagnetic survey systems commonly used (generally with frequencies less than 60 kHz) are unsuitable for detailed investigation of the upper 5 m of the earth or, as with ground‐penetrating radar, are most effective in relatively resistive environments. Most computer programs written for interpretation of data acquired with the low‐frequency systems neglect displacement currents, and are thus unsuited for accurate high‐frequency modeling and interpretation. New forward and inverse computer programs are described that include displacement currents in layered‐earth models. The computer programs and this new instrument are used to evaluate the effectiveness of shallow high‐frequency soundings based on measurement of the tilt angle and the ellipticity of magnetic fields. Forward model studies indicate that the influence of dielectric permittivity provides the ability to resolve thin layers, especially if the instrument frequency range can be extended to 50 MHz. Field tests of the instrument and the inversion program demonstrate the potential for detailed shallow mapping wherein both the resistivity and the dielectric permittivity of layers are determined. Although data collection and inversion are much slower than for low‐frequency methods, additional information is obtained inasmuch as there usually is a permittivity contrast as well as a resistivity contrast at boundaries between different materials. Determination of dielectric permittivity is particularly important for hazardous waste site characterization because the presence of some contaminants may have little effect on observed resistivity but a large effect on observed permittivity.

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