PIER B | PIER Journals

2023-01-27

PIER B

Vol. 98, 59-75, 2023

doi:10.2528/PIERB22091106

download: 2

Efficient Computation of Sideband Power Losses in Pulse-Shifted Non-Uniform Time-Modulated Array with Arbitrary Element Pattern

Sujoy Mandal Sujit Kumar Mandal

This paper presents the mathematical formulation for the generalized closed-form expressions to calculate sideband power (P_SR) of a nonuniform period time modulated array (NTMA) antenna with volumetric geometry by using pulse shifting strategy. For the arbitrary array geometry, the generalized expression of P_SR is obtained by considering the universal omnidirectional element pattern in the form sin^aθ|cosθ|^b, a > -1, b > -1/2. Then, corresponding to different array structures such as linear, planar, and volumetric ones, the derived expression is simplified for different element patterns with possible combination of `a' and `b'. Through representative numerical results it is demonstrated that the obtained simplified expressions without hypergeometric function are useful to accurately calculate the amount of power losses due to sideband radiations with significantly less time than the conventional numerical integration (NI) method.

Efficient Computation of Sideband Power Losses in Pulse-shifted Non-uniform Time-modulated Array with Arbitrary Element Pattern

2023-01-04

PIER B

Vol. 98, 39-57, 2023

doi:10.2528/PIERB22090805

download: 14

Coupling Coefficient Calculation of Arbitrarily Positioned Rectangular Coils with Double Magnetic Shielding in Wireless Power Transfer Systems

Zhongqi Li Zhongbang Chen Jing Li Huadong Liu Qing Huang

Coupling coefficient is a key parameter for the coil design of wireless power transfer (WPT) systems. The accurate calculation of coupling coefficient is an important theoretical basis for optimizing the coil structure and improving the transmission efficiency in WPT systems. In this paper, the magnetic flux density distribution of rectangular spiral coils with double magnetic shielding is studied, and an analytical model of coupling coefficient between arbitrarily positioned rectangular spiral coils is established. First, the incident magnetic flux density is obtained based on the dual Fourier transformation and the relationship between the magnetic flux density and magnetic vector potential. Second, the reflected magnetic flux density in the region of the receiving coil is solved by using Poisson's equation, Laplace's equation and boundary conditions. Finally, the formula for the coupling coefficient between rectangular spiral coils is derived by the spatial frame transformation method and the integral method. The calculation results agree well with the finite element simulation value and experimental measurements, which verifies the correctness of the calculation formula of the coupling coefficient.

Coupling Coefficient Calculation of Arbitrarily Positioned Rectangular Coils with Double Magnetic Shielding in Wireless Power Transfer Systems

2022-12-21

PIER B

Vol. 98, 21-37, 2023

doi:10.2528/PIERB22101305

download: 79

3-D Metamaterial Based Terahertz Planoconcave Lenses for Linearly and Circularly Polarized Waves

Muthusamy Marishwari Venkatachalam Subramanian Zhengbiao Ouyang Natesan Yogesh

A three-dimensional negative index (NI) metamaterial (MTM) is realized at terahertz (THz) frequencies. The structure is comprised of orthogonally oriented cross-bars with arrows on each corner embedded in a dielectric cube. The proposed 3-D MTM is symmetric along all the principal axes and shows a polarization-insensitive, wide-incident-angle negative refractive index regime centered at 0.862 THz with an operational bandwidth of 0.234 THz (27.15{%}). Using staircase approximation, the proposed 3-D NI MTM has been designed into a THz parabolic planoconcave lens (PCL). A PCL made of a NI medium is a counterpart of a positive index planoconvex lens and focuses on the near-field region. The designed PCL shows 3-D focusing functionality for linearly and circularly polarized THz waves at 0.85 THz. The designed PCL has a short focal length and high numerical aperture (NA) with sub-wavelength focusing spot sizes. The computed FWHMs along transversal directions are 0.46λ(x) × 0.49λ(y) for transverse electric (TE) polarized wave, 0.46λ(x) × 0.49λ(y) for left-circularly polarized (LCP) wave and 0.50λ(x) × 0.42λ(y) for right-circularly polarized (RCP) wave, respectively. The corresponding back focal lengths of the realized PCLs are 1.07λ, 1.03λ and 0.98λ and the focal depths are 0.40λ, 0.48λ and 0.41λ for linear, LCP and RCP polarized waves, respectively. A short review of recent progress in manufacturing techniques for the fabrication of the proposed 3-D MTM is further highlighted. Since the proposed 3-D MTM PCL configurations show the far-field focusing of linearly/circularly polarized waves, imaging with high optical power requirements can be met for THz waveband applications.

3-D Metamaterial Based Terahertz Planoconcave Lenses for Linearly and Circularly Polarized Waves

2022-12-15

PIER B

Vol. 98, 1-19, 2023

doi:10.2528/PIERB22101113

download: 58

Gain-Bandwidth Enhancement of Tapered Fed Ellipsoid Antenna for EWB (23.16-776.59 GHz ) Applications Using EBG

Naineri Suguna Senthil Revathi

A compact extreme wide band (EWB) modified ellipsoid monopole antenna utilising electromagnetic band gap (EBG) technology is developed on a Rogers RT/Duroid 5880 substrate for high frequency millimetre (mm) wave applications including cellular, satellite, radar, and medical imaging. The proposed antenna design has an overall dimension of 40 mm x 30 mm x 0.787 mm and achieves EWB characteristics with a frequency range of 23.16 GHz to 776.59 GHz, a fractional impedance bandwidth (FBW) of 188.41%, and a bandwidth ratio (BR) of 33.53 by using a tapered feed and an EBG technique. The proposed antenna design attained a maximum peak gain of 17.91 dB and a peak radiation efficiency of 99.4%. On the basis of its high impedance wide bandwidth (IBW), FBW, BR, peak gain, and peak radiation efficiency, as well as its omnidirectional radiation properties at resonant frequencies, this compact antenna has the potential to be utilised for EWB applications. The HFSS 3-D solver is applied to characterize and analyse antenna performance.