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Sungtek Kahng,Hyeong-seok Kim 대한전기학회 2011 Journal of Electrical Engineering & Technology Vol.6 No.6
This paper investigates a method to tackle the resonance problems of the rectangular power-bus structure(PBS) using thin sheets loaded with periodic metal strips. The equivalent surface impedance of the proposed loading is calculated and involved in the expression of the impedance that accounts for in the PBS, in order to improve the resonance behavior of the original structure. The effects of the strips and the immediate surroundings are illustrated by a number of numerical experiments. Also the restrictions of the technique are addressed.
A Metamaterial-Based Handset Antenna with the SAR Reduction
Sungtek Kahng,Kyungseok Kahng,Inkyu Yang,Taejoon Park 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.2
A method to reduce the specific absorption rate(SAR) of the antenna for WiMAX mobile communication is proposed in this paper. The SAR reduction is achieved by miniaturizing the physical size of the antenna for the given resonance frequency by devising a metamaterial-composite right- and left-handed(CRLH) configuration-based radiator much smaller than the quarter-guided wavelength adopted a lot in the conventional planar inverted F antenna(PIFA) or modified monopole antenna. The proposed antenna is placed near the head-phantom and its SAR is evaluated by the full-wave simulations(SEMCAD X), where the metamaterial-inspired antenna is shown to have the lower value than a modified monopole as the reference in terms of the SAR.
Metamaterial CRLH Structure-based Balun for Common-Mode Current Indicator
Sungtek Kahng,Jinil Lee,Koon-Tae Kim,Hyeong-Seok Kim 대한전기학회 2014 Journal of Electrical Engineering & Technology Vol.9 No.1
We proposed a new PCB-type ‘common-mode current(Ic) and differential-mode current(Id) detector’ working for fast detection of Ic and Id from the differential-mode signaling, with miniaturization effect and possibility of cheaper fabrication. In order to realize this device, we suggest a branch-line-coupler balun having a composite right- and left-handed(CRLH) one-layer microstrip phase-shifting line as compact as roughly λg/14. The presented balun obviously is different from the conventional bent-&-folded delay lines or slits on the ground for coupling the lines on the top and bottom dielectrics. As we connect the suggested balun output ports of the differential-mode signal lines via the through-port named U and coupled-port named L, Ic and Id will appear at port Δ and port Σ of the present device, in order. The validity of the design scheme is verified by the circuit-and numerical electromagnetic analyses, and the dispersion curve proving the metamaterial characteristics of the geometry. Besides, the examples of the Ic and Id indicator are observed as the even and odd modes in differential-mode signal feeding. Also, the proposed device is shown to be very compact, compared with the conventional structure.
Sungtek Kahng(강승택),Inkyu Yang(양인규),Hyeong-Seok Kim(김형석) 대한전기학회 2013 전기학회논문지 Vol.62 No.4
The spurious electromagnetic radiation is generated due to the RF unbalanced current on a conductive cable connecting an electronic device to another. A metamaterial-based filtering geometry with frequency selectivity is suggested to reduce the radiation with a bandgap structure, where the right-handed inductance and capacitance stem from the transmission-like configuration between the cable and the metal protrusion, and the left-handed components come from the narrow cavities. The effect of the structure on the unbalanced current pulse and its spurious radiation is presented in the FDTD-method frame work.
The Field of Power/Ground Planes influenced by the HPEM Source, and its Damage Reduction
Sungtek Kahng,Hyeong-Seok Kim 대한전기학회 2012 Journal of Electrical Engineering & Technology Vol.7 No.3
This paper looks into the field inside the wide rectangular box structure that is excited by the High Power Electromagnetic(HPEM) source as a potential threat to electric grid and communication networks causing malfunction or destruction. The rectangular box is assumed power/ground planes and its internal field is calculated by the cavity model with the lightning strike excitation as an HPEM pulse. The accuracy of the calculation method employed here is validated through a 156mmX106mmX508μm parallel metallic plate case which is manufactured and tested, and is applied to the size of a building. With the help of the cavity model that takes into account loading, the level of the electric field is shown to decrease when a metal pillar is loaded between the power and ground planes.
Compact UHF 9th-Order Bandpass Filter with Sharp Skirt by Cascaded-Triplet CRLH-ZOR
Kahng, Sungtek,Lee, Boram,Park, Taejoon The Korean Institute of Electrical Engineers 2013 Journal of Electrical Engineering & Technology Vol.8 No.5
We propose a compact high-order(9th) UHF bandpass filter comprising the composite right-handed and left-handed(CRLH) zeroth-order resonators(ZORs) in the form of the three cascaded-triplets(CTs) newly applied to the ZOR filter which results in very steep skirt. The method is verified by circuit and EM simulations and measurement with metamaterial properties.
Study on the Effect of Metal-Wall Loading on the DC Power-Bus
Sungtek Kahng 한국전자파학회JEES 2005 Journal of Electromagnetic Engineering and Science Vol.5 No.4
The DC power-bus for the PCB is loaded with metal walls on its selected sides and is characterized electromagnetically. This is a novel concept of approach to mitigate the spurious resonance and finally signal integrity problems. In particular, the peak at DC, which is always in the way to secure parallel-plates' EMC, can be completely removed by the proposed method. Through the findings of this study, the effect of metal-loading of the power-bus will be presented along with the impression that the suggested technique can tackle the headaches of signal integrity, ground bounce, EMIs.
An Orthogonally Polarized Negative Resonance CRLH Patch Antenna
Kahng, Sungtek,Jeon, Jinsu,Park, Taejoon The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1
A novel fully-printed microstrip antenna with negative first resonance and dual polarization is proposed. The radiator is printed on the 1-layer substrate instead of multilayers. The -1st resonance results from a composite right- and left-handed(CRLH) structure that has a circumferentially interlocked gap capacitively coupling a patch with a shorted-ring. This compact antenna is provided with a dual-polarization capability by creating two orthogonal linear polarizations in one body with coaxial feeds. The design is carried out by doing full-wave EM field simulation which is compared with the measurement of the fabricated antenna prototype. The measured results give the gain of 5 dBi and the efficiency of 78% at the -1st resonance mode as the center frequency of a downlink channel of the bandwidth over 20 MHz with 29 dB polarization isolation for mobile communication.
Compact UHF 9th-Order Bandpass Filter with Sharp Skirt by Cascaded-Triplet CRLH-ZOR
Sungtek Kahng,Boram Lee,Taejoon Park 대한전기학회 2013 Journal of Electrical Engineering & Technology Vol.8 No.5
We propose a compact high-order(9th) UHF bandpass filter comprising the composite right-handed and left-handed(CRLH) zeroth-order resonators(ZORs) in the form of the three cascadedtriplets(CTs) newly applied to the ZOR filter which results in very steep skirt. The method is verified by circuit and EM simulations and measurement with metamaterial properties.