• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.5
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• pp.187-192
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• 2017

We investigated the effects of the CSRR-metamaterial on microstrip comb-line array antennas. Microstrip comb-line array antennas was designed with 12 radiators, gain of 16.09dBi and bandwidth of 0.24GHz in the 24GHz ISM band. The designed antenna had radiation beam perpendicular to the antenna plane, co-polarization gain of 16.09dBi and cross-polarization gain of -10.86dBi. the CSRR-metamaterial increased largely the impedance bandwidth of the antenna from 0.24GHz to 3.6GHz. however as co-polarization gain became 10.08dBi and cross-polarization gain became 14.1dBi, co-polarization was mixed with cross-polarization. And the antenna gain lowered by 1.99dB. On the investigation of the dependence on the split-direction of the CSRR rings, it showed nearly the same characteristics for up-splitted ring used case and down-splitted ring used case. However in the case of arranging up-splitted ring and down-splitted ring in alternation, co-polarization gain decreased to -1.29dBi and cross-polarization gain increased to 13.9dBi, which meant the wave was transited to cross-polarization majority wave.

• International Journal of Advanced Culture Technology
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• v.7 no.4
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• pp.236-241
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• 2019

This paper will read about a multichannel frequency-modulated continuous wave (FMCW) radar sensor with switching transmit (TX) antennas is developed at W-band. To achieve a high angular resolution, a uniform linear array consisting of 5 switching-TX and 12 receive (RX) antennas is employed with the digital beamforming technique. The overall radar front-end module comprises a W-band transceiver and TX/RX antennas. A multichannel transceiver module consists of 5 up-conversion and 12 down-conversion channels, where one of the TX channels is sequentially switched ON. For developing transmitter, we developed an HPA (high power amplified) MMIC chip for W-band radar system and fabricated a transmitter module using this chip. In order to develop the W-band transmitter, we analyzed the important antenna transition structure from HPA MMIC line to W/G (Waveguide)antenna via M/S(microstrip) and fabricated it with 5 transmission channels. As a result, the output power of the transmitter was within 1 dB of the error range after analysis and measurement under normal temperature and environmental conditions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.4
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• pp.77-82
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• 2017

As frequencies increase to the millimeter wave bands the cross sections of wave guides become smaller than a few millimeters, which cause sapatial problems in realization of spatial combining power amplifiers. In this paper we intented to overcome the problem by widening the width of wave guides using horn antenna principles. We designed a widened rectangular wave guide for using in spatial combining power amplifier in 60GHz ISM band(57-64GHz), and we installed Antipodal transition in the widened wave guide, and then we characterized it as a spatial combining power amplifier. For the compatibility of WR15 standard wave guide, we widened the width of WR15 to 7mm using principle of H-plane sectoral horn antenna and then installed 3 slots of back to back Antipodal transition. The designed spatial combining power amplifier showed good characteristics of return loss less than -22.4dB and insertion loss less than 0.53dB. However, as widening the width of the wave guide, additional modes such as $TE_{20}$, $TE_{30}$ in addition to $TE_{10}$ were accurred in the bandwidth of WR15, which restricted the bandwidth and widening of the width of the wave guide.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1133-1136
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• 2002

We designed and fabricated a low local oscillation (LO) power V-band CPW mixer module using a CPW-to-waveguide transition technology for the application of millimeter-wave wireless communication systems. The mixer was designed using a unique gate mixing architecture to achieve simultaneously a low LO input power, a high conversion gain, and good LO-RF isolation characteristics. The fabricated mixer exhibited a high conversion gain of 2 dB at a low LO power of 0 dBm. For data transmission of the 60 ㎓ wireless LNA systems, we fabricated a CPW-to-waveguide converter module of WR-15 type and mounted the fabricated mixer in the converter module. The fabricated V-band mixer exhibited a higher conversion gain and a lower LO input power than other reported V-band mixers.

• Polymer(Korea)
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• v.26 no.4
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• pp.462-467
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• 2002

Blends of polymethylmethacrylate (PMMA) with polyvinylidenefluoride (PVDF) were prepared by melt mixing and investigated for optical waveguide devices by using hot embossing process. The glass transition temperatures ($T_g$) of the blends were decreased with increasing PVDF contents. However, the crystalline of PMMA/PVDF blends was not appeared by DSC and XRD due to miscibility between PMMA and PVDF. Shear viscosities and refractive indices of the blends were decreased with increasing PVDF contents. Optical transmittances and absorption losses of the blends were improved with increasing PVDF contents. This is due to a decreasing of polarizability of molecules by fluorine molecule in the PVDF.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.38 no.11
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• pp.49-54
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• 2001

In this work, we developed a Ka-band hybrid 4-stage power amplifier module using GaAs pHEMTs and waveguide to microstrip transitions. It has high gain and high output power characteristics. We used a 10 mil- thickness duroid substrate to fabricate this power amplifier and waveguide to microstrip transitions. The fabricated waveguide to microstrip transition showed about 1 dB insertion loss(back to back) at 32 40 GHz. The measured results of power amplifier module showed over 1W output power at 36.1 - 37.1 GHz. And it showed 31 dBm output power, 24 dB power gain and 15 % power-added efficiency(PAE) at 36.5 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.10 s.101
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• pp.982-988
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• 2005

An analytic solution of circular aperture antenna with a feed transition is presented using a hybrid method of generalized scattering matrices and integral transform. The method can give an analytic solution to antennas with integrated filters or mode converters, etc. Scattering matrices and integral transform techniques are combined to accommodate discontinuities connected between an aperture and a feed waveguide, and radiated field from the aperture. The method gives radiation fields as well as return losses of the antenna.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.1
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• pp.11-17
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• 2013

A design method to achieve multiple band-rejection characteristics in a wideband circular slot antenna is presented. First, a wideband circular slot antenna fed by a coplanar waveguide is designed to operate in the frequency range between 2.3 and 11GHz, which covers WLAN, WiBro, WiMAX, and UWB frequency bands. Next, resonant frequency variations of rejection bands are examined with respect to different slot locations and lengths when slots are inserted on the ground conductor and the circular patch of the antenna. When arc-shaped slots are placed close to the circular transition from a feeding part, multiple notch bands are obtained. In this case, a half of the guided wavelength of the first notch band corresponds to the slot length and other notch bands are integer-multiple of the first band. Single notch band can be obtained when the slot is located off the transition part. Based on this study, a wideband circular slot antenna with five band-rejection frequency bands at 2.45, 3.5, 4.9, 7.35, and 9.8GHz is designed and fabricated. The first arc-shaped slots are located in the ground conductor close to the circular transition from a feeding part to generate notch bands at 2.45, 4.9, 7.35, and 9.8GHz, while the second slot for 3.73 GHz is placed on top side in the circular patch. The proposed design method is validated by good agreement between the simulated and measured results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.297-302
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• 2005

Right hand circularly polarized Ka band microstrip patch array antenna was designed, manufacture and measurement were carried out. In order to lower axial ratio performance sequential rotation array technique was used. With mono-pulse feed There are sum and delta channel. Waveguide to microstrip transition was used. The 512 array antenna was performed which axial ratio is about 1.ldB in the half power beam width and also 1.ldB at the normal direction. Directivity gain of designed antenna is 32dB.

• Journal of electromagnetic engineering and science
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• v.10 no.3
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• pp.150-157
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• 2010

We proposed a $4{\times}8$ array antenna with aperture-coupled patch antenna elements. The antenna was designed for 60 GHz operation and fabrication on the low-temperature cofired ceramic(LTCC) substrate($\varepsilon_r$=5.8). The feedline with the stub was designed to enhance the radiating element bandwidth and the transition characteristics between the waveguide (WG) and microstrip line(MSL). Through the optimization of the antenna and feedline geometry, the antenna gain and the performance of the 10 dB bandwidth were 20.2 dBi and 13 % up, respectively. The measured results agreed with the simulated ones.