Irradiation of a Six-Layered Spherical Model of Human Head in the Near Field of a Half-Wave Dipole Antenna

2010 ◽  
Vol 58 (3) ◽  
pp. 680-690 ◽  
Author(s):  
H. Khodabakhshi ◽  
A. Cheldavi
Keyword(s):  
Near Field ◽  
Spherical Model ◽  
Human Head ◽  
Dipole Antenna ◽  
Half Wave

A metamaterial absorber based high gain directional dipole antenna

2018 ◽  
Vol 10 (4) ◽  
pp. 430-436 ◽  
Author(s):  
Sarin Valiyaveettil Pushpakaran ◽  
Jayakrishnan M. Purushothama ◽  
Manoj Mani ◽  
Aanandan Chandroth ◽  
Mohanan Pezholil ◽  
...  
Keyword(s):  
Near Field ◽  
High Gain ◽  
Metamaterial Absorber ◽  
Dipole Antenna ◽  
Spatial Spectrum ◽  
Microwave Antenna ◽  
Radiation Characteristics ◽  
Directional Radiation ◽  
Half Wave ◽  
Absorption Mode

AbstractA novel idea for generating directional electromagnetic beam using a metamaterial absorber for enhancing radiation from a microwave antenna in the S-band is presented herewith. The metamaterial structure constitutes the well-known stacked dogbone doublet working in the absorption mode. The reflection property of the dogbone metamaterial absorber, for the non-propagating reactive near-field, is utilized for achieving highly enhanced and directional radiation characteristics. The metamaterial absorber converts the high-spatial reactive spectrum in the near-field into propagating low-spatial spectrum resulting in enhanced radiation efficiency and gain. The gain of a printed standard half-wave dipole is enhanced to 10 dBi from 2.3 dBi with highly directional radiation characteristics at resonance.

scholarly journals Design of Broadband Compact Canonical Triple-Sleeve Antenna Operating in UHF Band

2021 ◽  
Vol 21 (4) ◽  
pp. 291-298
Author(s):  
Chandana SaiRam ◽  
Damera Vakula ◽  
Mada Chakravarthy
Keyword(s):  
Wireless Communication ◽  
Instantaneous Frequency ◽  
Dipole Antenna ◽  
Frequency Range ◽  
Broadband Antenna ◽  
Operating Frequency Range ◽  
Half Wave ◽  
Measurement Results ◽  
Antenna Configuration ◽  
Good Agreement

In this paper, a novel compact broadband antenna at UHF frequencies is presented with canonical shapes. Hemispherical, conical and cylindrical shapes have all been considered for antenna configuration. The designed antenna provides an instantaneous frequency range from 370 to 5,000 MHz with omnidirectional characteristics. The antenna was simulated in CST Microwave Studio, fabricated and evaluated; the results are presented. The simulated and measurement results are in good agreement. The antenna has voltage standing wave ratio (VSWR) ≤ 1.9:1 in 400–570 MHz, 2,530–3,740 MHz and 4,180–4,620 MHz; it has VSWR ≤ 3:1 over the operating frequency range 370–5,000 MHz and the measured gain varies from -0.6 to 4.5 dBi over the frequency band. The concept of canonical-shaped antenna elements and the incorporation of triple sleeves resulted in a reduction of the length of the antenna by 62% compared to the length of a half-wave dipole antenna designed at the lowest frequency. The antenna can be used for trans-receiving applications in wireless communication.

Fast and numerically stable Mie solution of EM near field and absorption for stratified spheres

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Olivér Csernyava ◽  
Bálint Péter Horváth ◽  
Zsolt Badics ◽  
Sándor Bilicz
Keyword(s):  
Near Field ◽  
Human Head ◽  
Approximate Model ◽  
Head Model ◽  
Wave Regime ◽  
Content Type ◽  
Precise Calculation ◽  
Linearly Polarized ◽  
Numerical Instabilities ◽  
Computational Resources

Purpose The purpose of this paper is the development of an analytic computational model for electromagnetic (EM) wave scattering from spherical objects. The main application field is the modeling of electrically large objects, where the standard numerical techniques require huge computational resources. An example is full-wave modeling of the human head in the millimeter-wave regime. Hence, an approximate model or analytical approach is used. Design/methodology/approach The Mie–Debye theorem is used for calculating the EM scattering from a layered dielectric sphere. The evaluation of the analytical expressions involved in the infinite sum has several numerical instabilities, which makes the precise calculation a challenge. The model is validated through an application example with comparing results to numerical calculations (finite element method). The human head model is used with the approximation of a two-layer sphere, where the brain tissues and the cranial bones are represented by homogeneous materials. Findings A significant improvement is introduced for the stable calculation of the Mie coefficients of a core–shell stratified sphere illuminated by a linearly polarized EM plane wave. Using this technique, a semi-analytical expression is derived for the power loss in the sphere resulting in quick and accurate calculations. Originality/value Two methods are introduced in this work with the main objective of estimating the final precision of the results. This is an important aspect for potentially unstable calculations, and the existing implementations have not included this feature so far.

scholarly journals Efficient and Compact Near-Field Coupled Hybrid Antenna Using a Single Radiating Subwavelength Split-Ring Resonator

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 527
Author(s):  
Zinching Dang ◽  
Marco Rahm
Keyword(s):  
Resonance Frequency ◽  
Electromagnetic Waves ◽  
Ring Resonator ◽  
Near Field ◽  
Low Frequency ◽  
Split Ring Resonator ◽  
Dipole Antenna ◽  
Angular Width ◽  
Split Ring ◽  
Broadband Internet

Modern applications in the realms of wireless communication and mobile broadband Internet increase the demand for compact antennas with well defined directivity. Here, we present an approach for the design and implementation of hybrid antennas consisting of a classic feeding antenna that is near-field-coupled to a subwavelength resonator. In such a combined structure, the composite antenna always radiates at the resonance frequency of the subwavelength oscillator as well as at the resonance frequency of the feeding antenna. While the classic antenna serves as impedance-matched feeding element, the subwavelength resonator induces an additional resonance to the composite antenna. In general, these near-field coupled structures are known for decades and are lately published as near-field resonant parasitic antennas. We describe an antenna design consisting of a high-frequency electric dipole antenna at f d = 25 GHz that couples to a low-frequency subwavelength split-ring resonator, which emits electromagnetic waves at f SRR = 10.41 GHz. The radiating part of the antenna has a size of approximately 3.2 mm × 8 mm × 1 mm and thus is electrically small at this frequency with a product k · a = 0.5 . The input return loss of the antenna was moderate at − 18 dB and it radiated at a spectral bandwidth of 120 MHz. The measured main lobe of the antenna was observed at 60 ∘ with a − 3 dB angular width of 65 ∘ in the E-plane and at 130 ∘ with a − 3 dB angular width of 145 ∘ in the H-plane.

A novel measurement strategy to evaluate the human head as a transition medium for inductive ear-to-ear communication

2019 ◽  
Vol 64 (2) ◽  
pp. 233-241
Author(s):  
Jan-Christoph Edelmann ◽  
Dominik Mair ◽  
Thomas Ussmueller
Keyword(s):  
Low Power ◽  
Hearing Aids ◽  
State Of The Art ◽  
Near Field ◽  
Human Head ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Channel Characteristics ◽  
Coupling Factors ◽  
Novel Concept

Abstract This manuscript introduces a novel concept for measuring coil coupling for extremely loose-coupled coils (coupling factors k<10−6; mutual inductance values M<10−10 H). Such a coupling is found everywhere where the ratio of solenoid diameter to coil spacing is >50. Measuring these quantities with a low-power technology requires a sophisticated setup that goes beyond the sensitivity of state-of-the art approaches. The methodology is validated using laboratory measurements with three sets of solenoids (two ferrite-cored, one air-cored) and numerical simulations with COMSOL Multiphysics 5.2a, Stockholm, Sweden. The concept is then employed to investigate the channel characteristics for inductive through-the-head communication within the 3.155–3.195 MHz band. This selected part of the spectrum is in accordance with International Telecommunication Union Radio Regulation 5.116 for low-power wireless hearing aids. By applying a phantom solution, we demonstrate that human tissue layers are transparent for magnetic fields within these frequencies. However, the influence from the relative coil arrangement is evaluated in detail as it restricts the communication range significantly. The coupling results for off-the-shelf Sonion, Roskilde, Denmark, RF 02 AA 10 solenoids considering both lateral and axial displacements might be of special interest for a number of near-field applications.

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