• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.11a
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• pp.263-263
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• 2004

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.278-281
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• 1999

We designed and fabricated a travelingwave CPW(coplanar waveguide) electrode for LiNbO$_3$ optical modulator. To Investigate the variation of microwave refractive index of these electrodes, we prepared the CPW electrode samples as a function of electrode thickness and measured the TDR and S-parameter. From this results, we could know the electrode conditions of index matching to 2.20 for 1150 nm optical wave index for applying LiNbO$_3$ optical modulator. Also we discussed the some properties of CPW electrode for applying LiNbO$_3$ optical modulator.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.10 s.89
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• pp.938-943
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• 2004

In this paper, we propose a T-shaped DGS for CPW and provide the closed-form solutions for power loss rate, and bandwidth of the DGS. The proposed T-shaped DGS structure has a range of capacitance(C) 5.5 times wider than the dumbbell-shaped DGS structure. In addition we also analyze relations between R, L, C values of the DGS equivalent circuit and total loss rate, BW, $\omega_0$ of the DGS.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.12
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• pp.1322-1332
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• 2008

In this paper, we proposed a divided two-arms spiral slot antenna fed by coplanar waveguide using the magnetic flow at slots. This antenna has characteristics of which one is to short-circuit at the end of the slot and another is to turn spirals separately. To reduce the offset of magnetic flow, two spiral slots are fed by 1800 phase difference. Because we proposed a printed two-arms spiral slot antenna without a balun circuit, antenna size become smaller substantially. And frequency characteristics are studied using the various design parameters. The bandwidth of the realized antenna is $2.7{\sim}12\;GHz$ below the return loss of -10 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.537-543
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• 2010

This paper presents a slot-shaped defected ground structure(DGS) which has multi-band rejection property. The proposed structure, in which the spiral slot-shaped defects with different size are aligned in the transverse direction to the guiding direction of the coplanar waveguide(CPW), provides multiple resonance frequencies. Compared with the simulated results, the band rejection characteristic is in good agreement with the measurement. Also, an equivalent circuit model of the proposed structure is presented, where the DGS on the ground plane is modeled as LC-resonators. This resonators are inductively coupled to the signal line through mutual inductance. From the equivalent circuit model, multi-band rejection property was derived.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.616-619
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• 2003

This work presents the design, fabrication and microwave performance of distributed analog phase shifter (DAPS) fabricated on $(Ba,\;Sr)TiO_3$ (BST) thin films for X-band applications. Ferroelectric BST thin films were deposited on MgO substrates by pulsed laser deposition. The DAPS consists of high impedance coplanar waveguide (CPW) and periodically loaded tunable BST interdigitated capacitors (IDC). In order to reduce the insertion loss of DAPS and to remove the alteration of unloaded CPW properties according to an applied dc bias voltage, BST layer under transmission lines were removed by photolithography and RF-ion milling. The measured results are in good agreement with the simulated results at the frequencies of interest. The measured differential phase shift based on BST thin films was $24^{\circ}$ and the insertion loss decreased from 1.1 dB to 0.7 dB with increasing the bias voltage from 0 to 40V at 10 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.12
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• pp.1371-1379
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• 2010

This paper presents an analysis of impulse dispersion for impulse radio ultra-wide band(IR-UWB) antenna. A set of antenna structure configurations are highlighted with verification based on the STFT(Short Time Fourier Transform) in 3.1~5.1 GHz: first, a taper-slotted antenna allowing the optimal impulse transmission, and second, 4 types of the omni-directional IR-UWB antenna using different feed structures(microstrip line, and CPW(Coplanar Waveguide)). The proposed STFT allows the analysis of the IR-UWB antenna's dispersion characteristic.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9A
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• pp.934-940
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• 2008

In this paper, an antenna accessible to the Hepta-Band (GPS, DCS, PCS, UMTS, Wibro, Bluetooth and S-DMB) is designed and fabricated. To get broadband characteristics with small size, we propose a structure of Coplanar Waveguide-fed with Ground, which is based on a monopole antenna. Simulation is performed by adjusting the size of distance between a length of radiation patch and ground plane. The designed antenna satisfies the frequency bandwidth of 1.430Hz$\sim$2.9GHz(67.89%), the gain of $1.3{\sim}3.7dBi$ and an omni-directional radiation pattern at VSWR<2.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.2
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• pp.53-55
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• 2011

The printed wide band monopole antenna having characteristics of dipole by modified coplanar wave guide(CPW) ground plane is presented. We are called a slot-arm printed monopole antenna and investigated the effect of the surface currents of the radiator on ground plane. The proposed antenna is treated as two asymmetric dipoles with the included angle of $90^{\circ}$ degrees which lie along Z-direction symmetrically. It is observed that the effect of the surface currents on the radiation patterns is similar to that of the corresponding dipole. The length and width of the ground plane correspond the radius and length of the dipole respectively. This approach is also valid to general printed monopole antennas. The simulation impedance bandwidth of the proposed antenna the range of 2.4 to 4.6 [GHz] for a voltage stand wave ratio (VSWR)${\leq}$2 and got pick gain of 6 [dBi]. So the proposed antenna is satisfied the requirement of the industry science medical (ISM) band operation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.9
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• pp.1968-1974
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• 1997

In this paper, the spectral domain approach is employed to investigate the characteristics of symmetrical and asymmetrical broadside-coupleed coplanar waveguides(BSC-CPW). These structures have large even(c)-odd(.pi.) mode-velocity ratio, suitable for wide-band and tight-coupling microwave circuit design. Efficient design parameters can be obtained from the effective dielectric constants and characteristic impedances calculated by varying the strip widths and slot widths in the BSC-CPW structure.