Yeow Beng Gan - Academia.edu (original) (raw)

Papers by Yeow Beng Gan

IEEE Antennas and Propagation Society International Symposium, Jun 22, 2003

Using the finite-difference time-domain (FD-TD) method in the Cartesian coordinate system, the co... more Using the finite-difference time-domain (FD-TD) method in the Cartesian coordinate system, the coupling effects in some (a)symmetrical edge-coupled V-shape and trapezoidal microshield transmission lines (MTLs) are studied. The hybrid effects of different geometrical parameters of the MTLs and the permittivity of the filling materials on the coupling coefficient are examined and compared. It is shown that the edge-coupled V-shape geometry is effective in reducing coupling over a wide frequency range.

2007 Asia-Pacific Microwave Conference, 2007

... P. Mahachoklertwattana1, PH Pathak1, Chao-Fu Wang2, and Yeow-Beng Gan3 1ElectroScience Lab, T... more ... P. Mahachoklertwattana1, PH Pathak1, Chao-Fu Wang2, and Yeow-Beng Gan3 1ElectroScience Lab, The Ohio State University, 1320 Kinnear Road ... matrix are evalutated in terms of an accurate asymptotic closed form approximation for the multilayered Green's function, which ...

IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450)

Scattering by Partially Buried Cylinders at the Rough Surface Interface Between Two Media Xiande ... more Scattering by Partially Buried Cylinders at the Rough Surface Interface Between Two Media Xiande Wang", Yeow-Beng Gan', and Le-Wei Li2 'Temasek Laboratories ... Note that Y'" is incident field, G<>(r,r') and G)(r,r') are the Green's functions for region 0 and region 1, where Go(r ...

IEEE Antennas and Propagation Society Symposium, 2004., 2004

... Xiande Wang", Yeow-Beng Gan', and Le-Wei Li2 ... where F~(M) and A:(J) are similar ... more ... Xiande Wang", Yeow-Beng Gan', and Le-Wei Li2 ... where F~(M) and A:(J) are similar to (5) and (6), while PA(r,Z), eA(r,r9), and KC(r,r*)are the dyadic kernel and scalar Green's functions for a chiral body located entirely above half space [4]. The fields E'"~(J,M) and Hint(J,M) in an ...

Electromagnetic Materials, 2005

2010 IEEE Antennas and Propagation Society International Symposium, 2010

Ultra-wideband (UWB) RADAR based technologies have been gaining popularity recently for through-w... more Ultra-wideband (UWB) RADAR based technologies have been gaining popularity recently for through-wall detection and surveillance applications. In this paper, the design and implementation of antenna for such applications is presented. An exponentially tapered slot (Vivaldi) antenna[1] is adopted. The tapered slot element being a travelling wave structure has inherently wide bandwidth with added advantages of high gain and low weight. Arrays based on Vivaldi elements have been extensively studied[2,3]. The current design is based on a segmented approach[2] with design of antenna element or array configuration based on radiation pattern requirements, followed by design of balun feed for individual elements and finally the design of feed network for broadside radiation. In each step, the objective of good impedance match and hence low insertion loss leads to the desired bandwidth performance in the final design.

IEEE Antennas and Propagation Society Symposium, 2004., 2004

A method based on integral equation (IE) coupled with physical optics (PO) method is proposed for... more A method based on integral equation (IE) coupled with physical optics (PO) method is proposed for the analysis of antennas in the presence of a large three-dimensional (3D) dielectric radome. The electric field integral equation (EFIE) is applied to the conducting surfaces of the antenna array enclosed within a large 3D radome. Equivalent PO surface currents aree assumed on the

Electromagnetic Materials - Proceedings of the Symposium F, ICMAT 2003, 2003

2005 Asia-Pacific Microwave Conference Proceedings

This paper presents an accurate and efficient full-wave method, combined with iterative adjoint t... more This paper presents an accurate and efficient full-wave method, combined with iterative adjoint technique, for analyzing sensitivities of planar microwave circuits with respect to design parameters. The method of moments (MoM) in spatial domain is utilized, and the generalized conjugate residual (GCR) iterative scheme is applied to solve the linear matrix equations with fast convergence. Green's functions for multilayer planar structures in the discrete complex image method (DCIM) form are employed to simplify the spatial domain manipulation. In the present method, a conventional integration model and the corresponding adjoint model are solved by the MoM, respectively. The adjoint technique, with the aid of iterative schemes, could considerably reduce the computational requirements, especially for the electrically large-size device with many perturbing design parameters. Numerical results of S-parameter sensitivities of a low pass microstrip filter by the present method are presented.

Microwave and Optical Technology Letters, 2003

Microwave and Optical Technology Letters, 2001

A novel and broadband semidisk microstrip antenna suitable for a portable and compact terminal in... more A novel and broadband semidisk microstrip antenna suitable for a portable and compact terminal integrated with the 3G IMT‐2000 cellular system, DECT mobile system, and Bluetooth wireless technology is discussed both theoretically and experimentally. Using both bandwidth‐enhancement and size‐miniaturization methods, a broad impedance bandwidth (return loss ≤−10 dB) of 32.4% from 1.86 to 2.58 GHz is obtained. Typical characteristics of the proposed antenna are addressed and discussed. Good agreements are obtained in the measured and simulated results. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 204–207, 2002.

Journal of Applied Physics, 2007

IEE Proceedings - Circuits, Devices and Systems, 2003

Expenlnentdl and simulation results are presented for the performance evaluation of various on-ch... more Expenlnentdl and simulation results are presented for the performance evaluation of various on-chip spiral inductors on GaAs substrates. These inductors were fabricated with ditTerent track widths and tum numbers, but identical track spacing. Based on the proposed equivalent lumped circuit model for the inductors and the experimental de-embedded S-parameters, the inductance. Q-factor, self-resonance frequency, and figure-of-merit indicator of these inductors are determined. Excellent agreement between measurement and simulation results is achieved. Some local scalable formulas are obtained to describe the global performance of these inductors.

IEEE Transactions on Antennas and Propagation, 2007

The interaction of electromagnetic waves with an arbitrarily shaped three-dimensional (3-D) homog... more The interaction of electromagnetic waves with an arbitrarily shaped three-dimensional (3-D) homogeneous chiral object located above a lossy half space is investigated using the method of moments (MoM) via the coupled mixed potential integral equations (MPIEs). Based on the surface equivalence principle, the equivalent surface electric and magnetic currents are used to replace the homogeneous chiral target in the presence of the half space. Two coupled MPIEs are developed for the unknown equivalent surface electric and magnetic currents by utilizing the continuity condition of the tangential total electric and magnetic field components on the chiral body's surface. The well-known Galerkin procedure with Rao-Wilton-Glisson (RWG) basis functions is applied to solve this problem. The spatial domain half-space Green's functions are obtained from the corresponding spectral domain Green's functions via the discrete complex image method (DCIM) combined with the generalized-pencil of function (GPOF) technique. The reciprocity theorem is employed to calculate the far-zone scattered field. Numerical results are presented for characterizing electromagnetic scattering by a 3-D arbitrarily shaped homogenous chiral object located above a lossy half space so as to demonstrate the accuracy and efficiency of the proposed technique. Index Terms-Discrete complex image method, electromagnetic scattering, homogeneous chiral target, integral equations, method of moments (MoM).

Acta Materialia, 2007

The effects of concentration of Bi 2 O 3 and sintering temperature on DC resistivity, complex rel... more The effects of concentration of Bi 2 O 3 and sintering temperature on DC resistivity, complex relative permittivity and permeability of MgFe 1.98 O 4 ferrite ceramics were studied. The objective of the study was to develop magneto-dielectric materials, with almost equal values of permeability and permittivity, as well as low magnetic and dielectric loss tangent, for the design of antennas with reduced physical dimensions. It was found that the poor densification and slow grain growth rate of MgFe 1.98 O 4 can be greatly improved by the addition of Bi 2 O 3 , because liquid phase sintering was facilitated by the formation of a liquid phase layer due to the low melting point of Bi 2 O 3. It was found that 3% Bi 2 O 3 can result in fully sintered MgFe 1.98 O 4 ceramics. The DC resistivities of the MgFe 1.98 O 4 ceramics were increased as a result of the addition of Bi 2 O 3 , except for 0.5%. The exceptionally low resistivities of the 0.5% samples were explained by a 'cleaning' effect of the small amount of liquid phase at the samples' grain boundaries. The electrical and magnetic properties of the MgFe 1.98 O 4 ceramics exhibited a strong dependence on the concentration of Bi 2 O 3. The 0.5% samples were found to have the highest dielectric loss tangents, which can be understood similarly to the DC resistivity results. The 2-3% Bi 2 O 3 is required to attain low dielectric loss MgFe 1.98 O 4 ceramics for antenna application. Low concentration of Bi 2 O 3 increased the static permeability of the MgFe 1.98 O 4 ceramics owing to the improved densification and grain growth, while too high a concentration led to decreased permeability owing to the incorporation of the non-magnetic component (Bi 2 O 3) and retarded grain growth. However, the addition of Bi 2 O 3 alone is not able to produce magneto-dielectric materials based on MgFe 1.98 O 4 ceramics, and further work is necessary to modify the permeability using cobalt (Co).

2007 IEEE Antennas and Propagation International Symposium, 2007

Progress In Electromagnetics Research, 2006

The open-sleeve antenna is analyzed using the method of moment. Emphasis is given to the analysis... more The open-sleeve antenna is analyzed using the method of moment. Emphasis is given to the analysis of the VSWR of the antenna. The multi-band characteristic of the sleeve antenna are investigated. The 1st and the 3rd frequency bands come from the driven dipole, and the 2nd frequency band is due to the length of parasitic elements and the distance between the driven element and the parasitic elements. Some useful results are presented and discussed in this paper.

Microwave and Optical Technology Letters, May 8, 2003

IEEE Antennas and Propagation Society Symposium, 2004., 2004

IEEE Antennas and Propagation Society International Symposium, Jun 22, 2003

Using the finite-difference time-domain (FD-TD) method in the Cartesian coordinate system, the co... more Using the finite-difference time-domain (FD-TD) method in the Cartesian coordinate system, the coupling effects in some (a)symmetrical edge-coupled V-shape and trapezoidal microshield transmission lines (MTLs) are studied. The hybrid effects of different geometrical parameters of the MTLs and the permittivity of the filling materials on the coupling coefficient are examined and compared. It is shown that the edge-coupled V-shape geometry is effective in reducing coupling over a wide frequency range.

2007 Asia-Pacific Microwave Conference, 2007

... P. Mahachoklertwattana1, PH Pathak1, Chao-Fu Wang2, and Yeow-Beng Gan3 1ElectroScience Lab, T... more ... P. Mahachoklertwattana1, PH Pathak1, Chao-Fu Wang2, and Yeow-Beng Gan3 1ElectroScience Lab, The Ohio State University, 1320 Kinnear Road ... matrix are evalutated in terms of an accurate asymptotic closed form approximation for the multilayered Green's function, which ...

IEEE Antennas and Propagation Society International Symposium. Digest. Held in conjunction with: USNC/CNC/URSI North American Radio Sci. Meeting (Cat. No.03CH37450)

Scattering by Partially Buried Cylinders at the Rough Surface Interface Between Two Media Xiande ... more Scattering by Partially Buried Cylinders at the Rough Surface Interface Between Two Media Xiande Wang", Yeow-Beng Gan', and Le-Wei Li2 'Temasek Laboratories ... Note that Y'" is incident field, G<>(r,r') and G)(r,r') are the Green's functions for region 0 and region 1, where Go(r ...

IEEE Antennas and Propagation Society Symposium, 2004., 2004

... Xiande Wang", Yeow-Beng Gan', and Le-Wei Li2 ... where F~(M) and A:(J) are similar ... more ... Xiande Wang", Yeow-Beng Gan', and Le-Wei Li2 ... where F~(M) and A:(J) are similar to (5) and (6), while PA(r,Z), eA(r,r9), and KC(r,r*)are the dyadic kernel and scalar Green's functions for a chiral body located entirely above half space [4]. The fields E'"~(J,M) and Hint(J,M) in an ...

Electromagnetic Materials, 2005

2010 IEEE Antennas and Propagation Society International Symposium, 2010

Ultra-wideband (UWB) RADAR based technologies have been gaining popularity recently for through-w... more Ultra-wideband (UWB) RADAR based technologies have been gaining popularity recently for through-wall detection and surveillance applications. In this paper, the design and implementation of antenna for such applications is presented. An exponentially tapered slot (Vivaldi) antenna[1] is adopted. The tapered slot element being a travelling wave structure has inherently wide bandwidth with added advantages of high gain and low weight. Arrays based on Vivaldi elements have been extensively studied[2,3]. The current design is based on a segmented approach[2] with design of antenna element or array configuration based on radiation pattern requirements, followed by design of balun feed for individual elements and finally the design of feed network for broadside radiation. In each step, the objective of good impedance match and hence low insertion loss leads to the desired bandwidth performance in the final design.

IEEE Antennas and Propagation Society Symposium, 2004., 2004

A method based on integral equation (IE) coupled with physical optics (PO) method is proposed for... more A method based on integral equation (IE) coupled with physical optics (PO) method is proposed for the analysis of antennas in the presence of a large three-dimensional (3D) dielectric radome. The electric field integral equation (EFIE) is applied to the conducting surfaces of the antenna array enclosed within a large 3D radome. Equivalent PO surface currents aree assumed on the

Electromagnetic Materials - Proceedings of the Symposium F, ICMAT 2003, 2003

2005 Asia-Pacific Microwave Conference Proceedings

This paper presents an accurate and efficient full-wave method, combined with iterative adjoint t... more This paper presents an accurate and efficient full-wave method, combined with iterative adjoint technique, for analyzing sensitivities of planar microwave circuits with respect to design parameters. The method of moments (MoM) in spatial domain is utilized, and the generalized conjugate residual (GCR) iterative scheme is applied to solve the linear matrix equations with fast convergence. Green's functions for multilayer planar structures in the discrete complex image method (DCIM) form are employed to simplify the spatial domain manipulation. In the present method, a conventional integration model and the corresponding adjoint model are solved by the MoM, respectively. The adjoint technique, with the aid of iterative schemes, could considerably reduce the computational requirements, especially for the electrically large-size device with many perturbing design parameters. Numerical results of S-parameter sensitivities of a low pass microstrip filter by the present method are presented.

Microwave and Optical Technology Letters, 2003

Microwave and Optical Technology Letters, 2001

A novel and broadband semidisk microstrip antenna suitable for a portable and compact terminal in... more A novel and broadband semidisk microstrip antenna suitable for a portable and compact terminal integrated with the 3G IMT‐2000 cellular system, DECT mobile system, and Bluetooth wireless technology is discussed both theoretically and experimentally. Using both bandwidth‐enhancement and size‐miniaturization methods, a broad impedance bandwidth (return loss ≤−10 dB) of 32.4% from 1.86 to 2.58 GHz is obtained. Typical characteristics of the proposed antenna are addressed and discussed. Good agreements are obtained in the measured and simulated results. © 2002 John Wiley & Sons, Inc. Microwave Opt Technol Lett 32: 204–207, 2002.

Journal of Applied Physics, 2007

IEE Proceedings - Circuits, Devices and Systems, 2003

Expenlnentdl and simulation results are presented for the performance evaluation of various on-ch... more Expenlnentdl and simulation results are presented for the performance evaluation of various on-chip spiral inductors on GaAs substrates. These inductors were fabricated with ditTerent track widths and tum numbers, but identical track spacing. Based on the proposed equivalent lumped circuit model for the inductors and the experimental de-embedded S-parameters, the inductance. Q-factor, self-resonance frequency, and figure-of-merit indicator of these inductors are determined. Excellent agreement between measurement and simulation results is achieved. Some local scalable formulas are obtained to describe the global performance of these inductors.

IEEE Transactions on Antennas and Propagation, 2007

The interaction of electromagnetic waves with an arbitrarily shaped three-dimensional (3-D) homog... more The interaction of electromagnetic waves with an arbitrarily shaped three-dimensional (3-D) homogeneous chiral object located above a lossy half space is investigated using the method of moments (MoM) via the coupled mixed potential integral equations (MPIEs). Based on the surface equivalence principle, the equivalent surface electric and magnetic currents are used to replace the homogeneous chiral target in the presence of the half space. Two coupled MPIEs are developed for the unknown equivalent surface electric and magnetic currents by utilizing the continuity condition of the tangential total electric and magnetic field components on the chiral body's surface. The well-known Galerkin procedure with Rao-Wilton-Glisson (RWG) basis functions is applied to solve this problem. The spatial domain half-space Green's functions are obtained from the corresponding spectral domain Green's functions via the discrete complex image method (DCIM) combined with the generalized-pencil of function (GPOF) technique. The reciprocity theorem is employed to calculate the far-zone scattered field. Numerical results are presented for characterizing electromagnetic scattering by a 3-D arbitrarily shaped homogenous chiral object located above a lossy half space so as to demonstrate the accuracy and efficiency of the proposed technique. Index Terms-Discrete complex image method, electromagnetic scattering, homogeneous chiral target, integral equations, method of moments (MoM).

Acta Materialia, 2007

The effects of concentration of Bi 2 O 3 and sintering temperature on DC resistivity, complex rel... more The effects of concentration of Bi 2 O 3 and sintering temperature on DC resistivity, complex relative permittivity and permeability of MgFe 1.98 O 4 ferrite ceramics were studied. The objective of the study was to develop magneto-dielectric materials, with almost equal values of permeability and permittivity, as well as low magnetic and dielectric loss tangent, for the design of antennas with reduced physical dimensions. It was found that the poor densification and slow grain growth rate of MgFe 1.98 O 4 can be greatly improved by the addition of Bi 2 O 3 , because liquid phase sintering was facilitated by the formation of a liquid phase layer due to the low melting point of Bi 2 O 3. It was found that 3% Bi 2 O 3 can result in fully sintered MgFe 1.98 O 4 ceramics. The DC resistivities of the MgFe 1.98 O 4 ceramics were increased as a result of the addition of Bi 2 O 3 , except for 0.5%. The exceptionally low resistivities of the 0.5% samples were explained by a 'cleaning' effect of the small amount of liquid phase at the samples' grain boundaries. The electrical and magnetic properties of the MgFe 1.98 O 4 ceramics exhibited a strong dependence on the concentration of Bi 2 O 3. The 0.5% samples were found to have the highest dielectric loss tangents, which can be understood similarly to the DC resistivity results. The 2-3% Bi 2 O 3 is required to attain low dielectric loss MgFe 1.98 O 4 ceramics for antenna application. Low concentration of Bi 2 O 3 increased the static permeability of the MgFe 1.98 O 4 ceramics owing to the improved densification and grain growth, while too high a concentration led to decreased permeability owing to the incorporation of the non-magnetic component (Bi 2 O 3) and retarded grain growth. However, the addition of Bi 2 O 3 alone is not able to produce magneto-dielectric materials based on MgFe 1.98 O 4 ceramics, and further work is necessary to modify the permeability using cobalt (Co).

2007 IEEE Antennas and Propagation International Symposium, 2007

Progress In Electromagnetics Research, 2006

The open-sleeve antenna is analyzed using the method of moment. Emphasis is given to the analysis... more The open-sleeve antenna is analyzed using the method of moment. Emphasis is given to the analysis of the VSWR of the antenna. The multi-band characteristic of the sleeve antenna are investigated. The 1st and the 3rd frequency bands come from the driven dipole, and the 2nd frequency band is due to the length of parasitic elements and the distance between the driven element and the parasitic elements. Some useful results are presented and discussed in this paper.

Microwave and Optical Technology Letters, May 8, 2003

IEEE Antennas and Propagation Society Symposium, 2004., 2004