• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.3A
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• pp.435-442
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• 2000

In this paper, we analyzed RF-DC conversion efficiency for the dual -polarization rectenna and the antenna position changing. Dual-Polarization rectenna consist of a two major parts, receiving antenna and rectifying circuits. We made dual-polarization 2.45GHz rectenna using the two dipole antennas and patch antenna. Rectifying circuit is consisted by a Schottky-Barrier diode with a large forward current and reverse breakdown voltage. The results of RF-DC conversion efficiency for the each of designed dual-polarization rectenna has 69.1% with 360$\Omega$(dipole type) and 75.4% with 340$\Omega$(patch type ) optimum load resistor. When the each of dual-polarization rectenna has optimal load resistor, it's conversion efficiency shows of $\pm$20% in dipole type and $\pm$5 in patch type at 0~180。position.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.32A no.12
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• pp.166-172
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• 1995

A novel passive TE/TM polarization mode converter is fabricated by using poled polymer waveguides. The optic axis of the poling induced waveguide is slowly rotated by using a slowly varying structure of poling electrodes. Thus the polarization conversion is achieved as the guided mode propagates through the waveguide. The proposed device is simulated by a full vectorial beam propagation method (VBPM) for anisotropic medium. For the rotation length of 1 mm, the TE polarization of the guided mode is successfully converted to the TM polarization with negligible loss. Based on the simulation results, we fabricated the polarization converter which is tested by using 1.3 $\mu$m laser diode. TE to TM mode conversion is observed with a polarization extinction ratio higher than 30 dB, and the excess loss is less than 1 dB. The polarization conversion is relatively insensitive to wavelength since the device contains no periodic structures. These devices are easier to fabricate than others containing periodic structures.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.31-36
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• 1994

We present a structure of a reflective Fabry-Perot etalon with nonlinear Kerr material (Kerr FP etalon), and report the polarization conversion and the optical bistability of polarization conversion. A device proposed has high polarization conversion ratio, 100% or so, and good/broad optical bistablity for input pump intensity.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.5
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• pp.1-6
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• 2011

By incorporating a polarization-diversity loop configuration (PDLC), we have demonstrated inline conversion between transmission and reflection spectra of a fiber Bragg grating (FBG) without reconfiguration of the fiber filter structure. The proposed apparatus consists of a polarization beam splitter, an FBG, and two quarter-wave plates (QWP's). The inline conversion operation between transmission and reflection spectra of the FBG was performed by proper adjustment of QWP's within the proposed filter. The band rejection ratio and side-mode suppression ratio in transmission and reflection modes of the fabricated filter were measured as ~17.0[dB] and ~16.4[dB], respectively.

• ETRI Journal
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• v.18 no.4
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• pp.287-299
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• 1997

Integrated-optic polarization controlling devices such as polarizers, polarization splitters, and polarization converters, are proposed and demonstrated in nonlinear optic polymers. Poling-induced birefringence in electro-optic polymers is exploited to fabricate the devices. The polymeric waveguide polarizers show low excess losses, and extinction ratios of 20.7 dB and 17.1 dB for TM-pass and TE-pass polarizers, respectively. The polymeric waveguide polarization splitters exhibit TE-TM mode splittings with crosstalk of 14.2 dB and 10.1 dB for TM and TE mode splittings, respectively. The polymeric waveguide polarization converters show successful TE/TM polarization mode conversion with conversion efficiencies of higher than 30 dB. The device employs poling-induced waveguides which have slowly rotating azimuth angle of optic axis along the light propagation direction. The novel polarization converter is insensitive to wavelength and easier to fabricate than the other polarization converters containing periodic structures.

• Corrosion Science and Technology
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• v.17 no.1
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• pp.30-36
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• 2018

The high rate of corrosion of magnesium alloys makes it limited for industrial applications. Therefore, surface treatment is required to enhance their corrosion resistance. In our study, a chemical conversion coating for protecting the corrosion of the magnesium alloy, AZ31B, was prepared by using a phosphate-permanganate solution. The chemical conversion coating had a limited protection ability due to defects arising from cracks and pores in the coating layer. The sol-gel coating was prepared by using trimethoxymethylsilane (MTMS) and 3-glycidoxypropyltrimethoxysilane (GPTMS) as precursors, and aluminum acetyl acetonate as a ring opening agent. The corrosion protection properties of sol-gel and conversion coatings in 0.35wt% NaCl solution were measured by the electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization test. The EIS results indicated that the resistance of the chemical conversion coating with the sol-gel coating was significantly improved through the sol-gel sealed phosphate-permanganate conversion coating. The results of the potentiodynamic polarization test revealed that the sol-gel coating decreased the corrosion current density ($I_{corr}$). The SEM image showed that the sol-gel coating sealed conversion coating and improved corrosion protection.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.4 no.1
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• pp.59-65
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• 2000

This paper describes the characteristics of a one dimensional narrow-wall slotted waveguide array with a single-layer linear-to-circular polarization converter consisting of a dipole array. An external boundary value Problem of one slot and three dipoles, which approximates the mutual coupling between the dipole array and an edge slot extending over three faces of a rectangular waveguide, is formulated and analyzed by the method of moments; design of polarization conversion is conducted for this model as a unit element. If every unit element has perfect circular polarization, grating lobes appear in the array pattern due to the alternating slot angle: these are suppressed in this paper by changing the dipole angle and degrading the axial ratio of the unit element. The validity of the design is confirmed by the measurements. The dipole array has negligible effects upon slot impedance; the polarization conversion for existing narrow-wall slotted arrays is realized by add-on dipole array.

• Korean Journal of Remote Sensing
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• v.27 no.6
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• pp.729-741
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• 2011

Wind speeds have long been estimated from C-band VV-polarized SAR data by using the CMOD algorithms such as CMOD4, CMOD5, and CMOD_IFR2. Some SAR data with HH-polarization without any observations in VV-polarization mode should be converted to VV-polarized value in order to use the previous algorithms based on VV-polarized observation. To satisfy the necessity of polarization ratio (PR) for the conversion, we retrieved the conversion parameter from full-polarized SIR-C SAR image off the east coast of Korea. The polarization ratio for SIR-C SAR data was estimated to 0.47. To assess the accuracy of the polarization ratio coefficient, pseudo VV-polarized normalized radar cross section (NRCS) values were calculated and compared with the original VV-polarized ones. As a result, the estimated psudo values showed a good agreement with the original VV-polarized data with an root mean square error by 0.99 dB. We applied the psudo NRCS to the estimation of wind speeds based on the CMOD wind models. Comparison of the retrieved wind field with the ECMWF and NCEP/NCAR reanalysis wind data showed relatively small rms errors of 1.88 and 1.91 m/s, respectively. SIR-C HH-polarized SAR wind retrievals met the requirement of the scatterometer winds in overall. However, the polarization ratio coefficient revealed dependence on NRCS value, wind speed, and incident angle.

• ETRI Journal
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• v.41 no.2
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• pp.160-166
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• 2019

A novel analytical method based on the cavity mode theory to design a metasurface (MS) is proposed in this study. We carefully analyzed the phase and amplitude characteristics of the incident wave and transmitted wave, and successfully designed a circular polarization conversion MS by introducing a cutting structure with wider operation bandwidth and higher radiation direction gain compared with that of the original MS. For the measurements, a microstrip antenna operating at 2.4 GHz was used as the source antenna to verify the designed MS. The simulation and measurement results agree well with each other.

• Korean Journal of Optics and Photonics
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• v.32 no.1
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• pp.29-33
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• 2021

We have experimentally simulated the violation of the Leggett-Garg inequality (LGI) using a heralded-single-photon source via spontaneous parametric down-conversion (SPDC) in a periodically poled potassium titanyl phosphate (PPKTP) crystal. We measured the polarization fringe as a function of the angle of the linear polarization of the photons, and analyzed the LGI according to n measurement. Simulation results for LGI based on the polarization of the heralded single photon were in good agreement with theoretical calculations.