• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1375-1382
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• 2008

Frequency adjustable D-CRLH(dual-composite right/left handed) transmission lines, which solve the problem of design complexity and uncontrolled frequency of the existing structures, are proposed in this paper. The first design(type I), consisting of defected ground structure(DGS), island pattern in DGS, fixed stub and varactor diodes, controls $C_L$ in the parallel resonant circuit, while the second structure(type 2) composed of fixed DGS, shunt stub and diode adjusts $C_R$ in the series resonant circuit. The dual band frequency points which correspond to the meaningful electrical length of +/-90 degree in the RH/LH region are adjustable according to the bias voltage. The measurement shows that the LH frequency point which has -90 degree of electrical length are adjusted over $4.22{\sim}5.39\;GHz$ and $4.21{\sim}5.05\;GHz$ for type 1 and type 2, respectively, under $1{\sim}12\;V$ of bias voltage. In addition, the frequency Woo where RH turns over LH is controled over $3.26{\sim}4.22\;GHz$ for type 2 with the same bias condition.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1343-1351
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• 2010

In this paper, a novel patch antenna based on the metamaterial CRLH(Composite Right- and Left-Handed) structure is designed, implemented, and measured. Contrary to the standard microstrip patch's fundamental resonance mode of half-wavelength or its positive multiple, the proposed antenna shows the in-phase electric field over the entire antenna. The proposed antenna has a desired omni-directional field pattern which is typical characteristic of $\lambda/4$ monopole antenna, and also shows the merit of low profile. HFSS(High Frequency Structure Simulator) of Ansoft which is based on the FEM(Finite Element Method) is used to simulate the proposed antenna. FR-4 substrate of thickness 1.6 mm and relative permitivity 4.4 is used for the proposed antenna implementation. The implemented antenna showed VSWR (Voltage Standarding Wave Ratio)$\leq$2 for the frequency band from 2.63 GHz to 2.655 GHz which is used for S-DMB (Satellite-Digital Multimedia Broadcasting) service. And measured peak gain and efficiency are 2.65 dBi and 81.14 %, respectively.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.69-74
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• 2010

In this paper, we proposed a compact arbitrary dual-band band-stop filter using CRLH transmission line. The proposed filter used CRLH transmission line as stub and it developed dual-band band-stop characteristics using non-linear phase response of CRLH transmission line. The size of proposed filter is compact. And it can control arbitrary dual stop band. In this paper, designed band-stop filter at GPS band and ISM band As result, the S(2,1) is about -30dB at GPS band and about -29dB at ISM band. The fabricated filter is very compact. Its dimension is 10mm*15mm.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.8
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• pp.1429-1435
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• 2010

In this paper, a double lorentz composite right left handed(DL-CRLH) transmission line is designed using defected ground structure (DGS) and varactor diodes. Previously, the diode has been adopted only selectively for one of parallel or series resonators, and the balanced frequency as well as triple band frequencies were fixed. However in the proposed DL-CRLH transmission line, the balanced frequency, where the resonant frequencies of the series-connected parallel resonator and shunt-connected series resonator are the same, is adjustable. In addition, the triple band frequencies are controlled, too. The measured balanced frequency varies between 3.42~4.8GHz according to the controlled bias voltage. Under the same bias condition for the balanced frequency, the adjusted frequencies are 2.22~2.77GHz, 3.7~5.2GHz, 7.32~8.23GHz, 3.42~4.8GHz, and 4.44~5.92GHz for the conditions that ${\beta}d=+0.5{\pi}$, $-0.5{\pi}$, 2nd $+0.5{\pi}$, ${\omega}_{\infty}$, and ${\omega}_o$, respectively.

• Journal of Electrical Engineering and Technology
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• v.10 no.2
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• pp.653-658
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• 2015

This paper deals with an efficient optimization design method of a compact ultra wideband (UWB) filter which can improve the characteristics of the filter. The Evolution Strategy (ES) algorithm is adopted for the optimization and modified to suppress the ripple by inserting an additional step to the ES scheme. The algorithm has the ability to control the ripple of an insertion loss in a passband as a modified approach. During the modified ES, a structure of initial shape is changed a lot, while includes the stepped impedance (SI) and the composite right/left handed transmission line (CRLH-TL). And an optimized filter satisfies the UWB specifications on the stopband and passband with an acceptable insertion loss. The filter achieves a much developed shape, the size of $15{\times}14mm$, the 3dB bandwidth from 2.7 to 10.8GHz, the flat insertion-loss less than 1dB, the wide stopband with 12~20GHz, and an acceptable return loss.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.95-101
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• 2008

This paper presents a novel bandpass filter design method for suppressing spurious response in the GSM band and effectively reducing the overall size with the unbalanced-conditioned metamaterials. Compared to the conventional bandpass filters based on half-or quarter-wave resonators, the CRLH(composite right/left-handed) bandpass filter works excellently in harmonic-suppression by 40$\sim$50 dB and 80 %-miniaturization using the zero-order resonators bridged by Inductive-coupling Inverters suggested first time. The proposed technique, with the equivalent circuit and dispersion diagram, is validated by performance predictions and experiments.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1706-1711
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• 2013

This paper presents the filter of a resonator comprising a shorted open gap ring(SOGR) and interdigital lines. The proposed filter has the ultra wideband characteristic operating from 3 GHz to 10.5 GHz. In order to achieve the remarkable improvement in the size-reduction of the overall filter structure, only one cell of the SOGR with the inter-digital lines is adopted. It is shown that this filter has the size of $18mm{\times}15mm$ using a metamaterial, the fractional bandwidth over 100%, the insertion loss much less than 1dB, an acceptable return loss performance in the results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.8
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• pp.47-52
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• 2008

In order to enhance the rejection performance of the UWB bandpass filter based on the Composite Right- and Left-Handed Transmission-line(CRLH-TL) Metamaterial cell, we propose the lowpass filtering concept that fits into the design objectives : Keeping metamaterial property and miniaturization. So the bandpass filter itself is made far less than a quarter-wavelength and a pair of symmetric comprises lowpass filtering blocks are placed before and after the center CRLH filter which comprises tile interdigitated coupled lines and short-circuited stob. The design result will show the size of 'guided wavelength/8', the fractional bandwidth over 100%, the insertion loss much less than 1 dB, a flat Group-Delay and a good return loss performance, as expected.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1159-1163
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• 2012

In this paper, a new method is suggested to reduce the size of a wide-band array antenna. The power-divider for the feeding structure is made compact as ${\lambda}/8$ with the help of a novel Metamaterial UWB bandpass filter. This power divider is clearly different from others in that the proposed design uses microstrip structured Composite Right and Left-Handed (CRLH) filters, while others use two dielectric layers or long tapered transmission lines. In order to validate the proposed design method, the circuit and full-wave simulated results of the power divider with the Metamaterial UWB filters are compared to each other, and the Metamaterial properties of the structure are shown with the electric field at the ZOR and dispersion diagram. Furthermore, the antenna performance of the fabricated antenna with the power divider is measured and compared with the prediction. Also, the size reduction effect by the proposed scheme is addressed.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.85-89
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• 2011

In this paper, a novel Class-E power amplifier using metamaterials has been realized with one RF LDMOS diffusion metal-oxide-semiconductor field effect transistor. The CRLH structure can lead to metamaterial transmission line with the Class-E power amplifier tuning capability. The CRLH TL is achieved by the frequency offset and the nonlinear phase slope of the CRLH TL for the matching network of the power amplifier. Also, the proposed power amplifier has been realized by using the CRLH structure in the output matching network for better efficiency. Operating frequencies are chosen at 13.56 MHz in this work. The measured results show that the output power of 39.83 dBm and the gain of 11.83dB was obtained. At this point, we have obtained the power-added efficiency (PAE) of 73 % at operation frequency.