• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.12
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• pp.1058-1063
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• 2015

In this article, we propose a near field microwave scanning probe structure in which two short conducting rods are attached to the center of the ridged(H-type) aperture, thereby reducing significantly the beam spot area while maintaining the high transmission efficiency through the output coupling H-type(ridged) aperture. Here the two short parallel conducting rods seem to play an important role of concentrating the transmitted electromagnetic energy through the H-type aperture and so reducing the beam area for high resolution. For validation of the proposed theory, the near field waveguide probe is fabricated according to the simulated results and its return loss characteristics versus frequencies are measured. The comparison between theory and experiment is seen to be in good agreements.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.296-296
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• 2014

We investigate experimentally and theoretically the splitting of surface plasmon (SP) resonance peaks under TE- and TM-polarized illumination. The SP structure at infrared wavelength is fabricated with a 2-dimensional square periodic array of circular holes penetrating through Au (gold) film. In brief, the processing steps to fabricate the SP structure are as follows. (i) A standard optical lithography was performed to produce to a periodic array of photoresist (PR) circular cylinders. (ii) After the PR pattern, e-beam evaporation was used to deposit a 50-nm thick layer of Au. (iii) A lift-off processing with acetone to remove the PR layer, leading to final structure (pitch, $p=2.2{\mu}m$; aperture size, $d=1.1{\mu}m$) as shown in Fig. 1(a). The transmission is measured using a Nicolet Fourier-transform infrared spectroscopy (FTIR) at the incident angle from $0^{\circ}$ to $36^{\circ}$ with a step of $4^{\circ}$ both in TE and TM polarization. Measured first and second order SP resonances at interface between Au and GaAs exhibit the splitting into two branches under TM-polarized light as shown in Fig. 1(b). However, as the incidence angle under TE polarization is increased, the $1^{st}$ order SP resonance peak blue-shifts slightly while the splitting of $2^{nd}$ order SP resonance peak tends to be larger (not shown here). For the purpose of understanding our experimental results qualitatively, SP resonance peak wavelengths can be calculated from momentum matching condition (black circle depicted in Fig. 2(b)), $k_{sp}=k_{\parallel}{\pm}iG_x{\pm}jG_y$, where $k_{sp}$ is the SP wavevector, $k_{\parallel}$ is the in-plane component of incident light wavevector, i and j are SP coupling order, and G is the grating momentum wavevector. Moreover, for better understanding we performed 3D full field electromagnetic simulations of SP structure using a finite integration technique (CST Microwave Studio). Fig. 1(b) shows an excellent agreement between the experimental, calculated and CST-simulated splitting of SP resonance peaks with various incidence angles under TM-polarized illumination (TE results are not shown here). The simulated z-component electric field (Ez) distribution at incident angle, $4^{\circ}$ and $16^{\circ}$ under TM polarization and at the corresponding SP resonance wavelength is shown in Fig. 1(c). The analysis and comparison of theoretical results with experiment indicates a good agreement of the splitting behavior of the surface plasmon resonance modes at oblique incidence both in TE and TM polarization.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.470-477
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• 2017

As a method of the transmission efficiency improvement of an aperture smaller than the wavelength, we modified the conventional H-shaped resonant aperture to lower the resonance frequency of resonant aperture, and the transmission efficiency of resonant aperture was improved more than the conventional aperture. The maximum transmission cross section(TCS) calculated using the equivalent circuit tends to be almost equal to the maximum TCS from the small resonant aperture modified to improve the transmission efficiency. The transmission characteristics of resonant apertures can be quantified as the TCS, and the transmission efficiency of that can be compared. The modified resonant aperture has a maximum TCS increased by about 2.87 times from $846mm^2$ to $2,431mm^2$ compared to the H-shaped aperture, and the resonant frequency decreased from 5.06 GHz to 2.92 GHz, and the length-to-wavelength ratio of the aperture was reduced from 0.178 to 0.103.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.3
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• pp.402-405
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• 2012

In this paper, we proposed a novel metamaterial unit cell utilizing an interdigital capacitor(IDC) with non-bianisotropic property. Due to the induced magnetic resonance of an IDC unit cell, exotic effective constitutive parameters can be realized like a split ring resonator(SRR). Furthermore, the proposed unit cell is electrically smaller than a conventional SRR unit cell. The effective parameters retrieved from the transmission responses of waveguide measurement method and simulated results show good agreement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1272-1278
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• 2009

The cancellation method of P/G(power/ground) plane resonances which are generated between the power plane and the ground plane in a 4-layer PCB(Printed Circuit Boards) with a via-hole for the improvement of the RE(Radiated Emission) characteristic is presented. The validity of the proposed method was confirmed from simulation and measurement of performances of signal transmission characteristic, intensities of edge-radiation and radiated emission of PCB with a via-hole.

• Journal of electromagnetic engineering and science
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• v.16 no.4
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• pp.219-224
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• 2016

In this paper, coupled-mode theory (CMT) is used to obtain a transient solution analytically for a wireless power transfer system (WPTS) when unit energy is applied to one of two resonators. The solutions are compared with those obtained using equivalent circuit-based analysis. The time-domain CMT is accurate only when resonant coils are weakly coupled and have large quality factors, and the reason for this inaccuracy is outlined. Even though the time-domain CMT solution does not describe the WPTS behavior precisely, it is accurate enough to allow for an understanding of the mechanism of energy exchange between two resonators qualitatively. Based on the time-domain CMT solution, the critical coupling coefficient is derived and a criterion is suggested for distinguishing inductive coupling and magnetic resonance coupling of the WPTS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.997-1002
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• 2009

This Letter presents a wideband ENG(Epsilon Negative) ZOR(Zeroth-Order Resonant) antenna designed on a microstrip line. It has a mushroom structure and its size is only $7.65{\times}1.31{\times}2.37\;mm$(or $0.306{\times}0.053{\times}0.095\;{\lambda}_0$ at 12 GHz) owing to zeroth-order resonance. The design procedures with closed form solutions are provided using transmission line theory considering radiation loss. The measured antenna bandwidth is about 20.0 % at 9.2 GHz and antenna gain is 7.1 dBi despite the compact size.

• Progress in Superconductivity and Cryogenics
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• v.16 no.3
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• pp.21-25
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• 2014

As wireless power transfer (WPT) technology using strongly coupled electromagnetic resonators is a recently explored technique to realize the large power delivery and storage without any cable or wire, this technique is required for diffusion of electric vehicles (EVs) since it makes possible a convenient charging system. Typically, since the normal conducting coils are used as a transmitting coil in the CPT system, there is limited to deliver the large power promptly in the contactless EV charging system. From this reason, we proposed the combination CPT technology with HTS transmitting antenna, it is called as, superconducting contactless power transfer for EV (SUWPT4EV) system. As the HTS coil has an enough current density, it can deliver a mass amount of electric energy in spite of a small scale antenna. The SUCPT4EV system has been expected as a noble option to improve the transfer efficiency of large electric power. Such a system consists of two resonator coils; HTS transmitting antenna (Tx) coil and normal conducting receiver (Rx) coil. Especially, the impedance matching for each resonator is a sensitive and plays an important role to improve transfer efficiency as well as delivery distance. In this study, we examined the improvement of transmission efficiency and properties for HTS and copper antennas, respectively, within 45 cm distance. Thus, we obtained improved transfer efficiency with HTS antenna over 15% compared with copper antenna. In addition, we achieved effective impedance matching conditions between HTS antenna and copper receiver at radio frequency (RF) power of 370 kHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.12 no.1
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• pp.143-152
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• 2001

A method for miniaturization of microstrip patch antenna without degrading its radiation characteristics is investigated in this paper. It involves perforating the patch to form a microstrip square-ring antenna, and it's BW enhancement is investigated numerically and experimentally. A ring geometry introduces additional parameters to the antenna, and those are used to control impedances, resonance frequencies, and bandwidths. For a single square ring antenna, an increase of the size of perforation increases its input impedance, decreases the resonance frequency, and bandwidths. But it affects little on directivity of the antenna. To match the antenna to a transmission line and also enhance its bandwidth, the ring is stacked by a square patch or another square ring. Also numerically simulated results by the IE3D, and experimental data are compared for proof.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.9
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• pp.814-820
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• 2015

In this paper, A high selective dual-band bandpass filter was proposed using a dual-mode ring resonator with two short-circuited stubs. For dual-mode resonance, the ring resonator is directly connected with non-orthogonal feed-lines via coupling capacitors. Two short-circuited stubs which are unequal lengths are simultaneously placed at two corners along the two symmetry plane of the ring resonator in order to obtain dual-band responses. Because the feeding angle perturbated ring resonator of the proposed dual-band bandpass filter has the symmetrical structure, Even/Odd mode analysis can be well applied to extract the scattering parameters and transmission zero frequencies. The proposed dual-band bandpass filter was designed and fabricated for WLAN(Wireless Local Area Network) application of IEEE 802.11n standard. The measured results showed a good agreement with the simulation results, and it should be well applied not only for WLAN applications but also for any other communication systems.