• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.2
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• pp.338-346
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• 2018

In this paper, a monopole antenna applicable to WLAN/WiMAX system is designed and fabricated. The proposed antenna is designed to have three lines and one slit based on microstrip feeding to have triple band characteristics. We optimized the lengths and slits of the three lines to obtain the required characteristics for this paper. The proposed antenna has $32.0mm(W2+W3){\times}47.1mm$ (L3+L4+L5+L8) on a dielectric substrate of $42.5mm(W1){\times}52mm(L1){\times}1.0mm$ size. From the fabrication and measurement results, bandwidths of 158 MHz (813 to 971MHz), 630 MHz (2.10 to 2.73GHz) and 1190 MHz (4.83 to 6.02GHz) were obtained based on the impedance bandwidth. The fabricated antenna also obtained the measured gain and radiation pattern in the required triple band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.4
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• pp.358-368
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• 2016

In this paper, for the mechanical beam steering of the Cassegrain antenna, the steering performances of the main reflector tilting method are characterized, and the Cassegrain antenna for the antenna rotating method is designed and its performances are measured. In the Cassegrain antenna operating at W-band, the changes of characteristics due to changes in the sizes of the main/sub-reflectors and other structural changes are analyzed to obtain the structural variables satisfying the performance goal. The manufactured antenna in W-band shows the measured gain of 42.08 dBi, 3 dB beamwidth of $1.32^{\circ}$, $1.14^{\circ}$ and the return loss($S_{11}$) of -23.58 dB at the center frequency of 94 GHz.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.3
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• pp.21-26
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• 2024

Design and fabrication method of W-band 12-way radial power combiner is proposed in this paper. The proposed structure is used with TE₁₀ to TEM mode converter, which is realized using 2-step impedance transformer. The pin structure for mode converter is well bonded to the housing so that environment conditions such as vibration or shock are not affected. Proposed W-band power combiner has less than 0.7 dB insertion loss and more than 13 dB return loss from 88 GHz to 98 GHz. The measured output isolations between each other are greater than 7.5 dB from 82 to 100 GHz and phase differences are less than 10 degree from 88 to 96 GHz. Proposed power combiner is expected compact radar and various applications requiring for high power and stable environment conditions.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1218-1224
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• 2000

A half-height waveguide power combiner is designed and analyzed for Ka-band satellite application. The branch line directional coupler is utilized as a power combiner to achieve high port-to-port isolation and low insertion loss. The half height waveguide is adopted to reduce the volume and mass of a power combiner. In this paper a half height waveguide power combiner is designed and analyzed by FDTD and its performance is compared with that of a full-height waveguide power combiner. The designed half-height combiner having optimum order is manufactured and tested. The measurement shows that the designed half-height power combiner satisfies all the performance requirements (insertion loss less than 0.3 dB, reflection loss more than 20dB, port to port isolation more than 20 dB, and port to port phase difference within 5$^{\circ}$) in the satellite communication frequency band of 20.255 GHz to 21.255 GHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.3
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• pp.45-54
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• 2014

In this paper, We have designed and fabricated 20 InP Gunn diodes using a current limiting epitaxial structure by MINT's optimized fabrication processes. We have also packaged the fabricated InP Gunn diodes using our optimized packaging method, and then designed and fabricated a W-band waveguide FTO to measure characteristics of the packaged InP Gunn diodes. The packaged InP Gunn diode have a ceramic ring, a Au plated stud and a lid, and a Maltese cross. The fabricated InP Gunn diodes have good RF characteristics such as high output powers (11.8~17 dBm) and limiting low currents (less than 400 mA) between 92.9 and 94.78 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.76-79
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• 2016

This paper describes the successful development and the performance of X-band 50 W pulsed power amplifier using a 50 W GaN-on-SiC high electron mobility transistor. The GaN HEMT with a gate length of $0.25{\mu}m$ and a total gate width of 12 mm were fabricated. The X-band pulsed power amplifier exhibited an output power of 50 W with a power gain of 6 dB in a frequency range of 9.2~9.5 GHz. It also shows a maximum output power density of 4.16 W/mm. This 50 W GaN HEMT and X-band 50 W pulsed power amplifier are suitable for the radar systems and related applications in X-band.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.133-136
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• 2008

In this paper, the parallel coupled line(PCL) band-pass filter satisfying IEEE 802.11a (a:$5.15{\sim}5.25$, b:$5.25{\sim}5.35$, c:$5.725{\sim}5.875$ [GHz]) has been designed for 5[GHz]band W-Lan RX-System applications. The designed PCL Band-Pass filter is of advantage to make a design formula that is small, light and approximate accuracy. It choose a microstrip plane figure because it is possible that a multiplicity of resonator was designed. It was shown that bandwidth was 14% from 5.15GHz to 5.92GHz at the -3dB designed filter. As a result, it is enough to use the designed filter at W-LAN RX-system of the 5GHz band.

• Journal of Advanced Navigation Technology
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• v.24 no.5
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• pp.415-422
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• 2020

Federal Communications Commissions (FCC) has adopted a new rule that can provide a 1,200 MHz unlicensed spectrum to maximize the public benefits in the 5.925 ~ 7.125 GHz(6 GHz) band by expanding unlicensed broadband into the 6 GHz band while also ensuring that licensed services that operate in the band continue to thrive. In Korea, the M/W band of 6 GHz has been reallocated to introduce unlicensed services in the 6 GHz band. Considering the national interests, the entire 1,200 MHz will be supplied for the indoor uses, but only the 500 MHz of the lower bandwidth (5925 ~ 6425 MHz) will for the outdoor uses under the limited power to protect the incumbent services. The introduction of unlicensed devices is being actively promoted through the reallocation of the 6 GHz M/W band, but since it is desperately necessary to prepare technical requirements to operate them in Korea. In this paper, the US 6 GHz unlicensed rules has been analyzed, these results will be utilized for establishing Korean technical standards with the unlicensed spectrum expansion.

• Journal of the Institute of Electronics and Information Engineers
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• v.49 no.10
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• pp.159-168
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• 2012

In this paper, a W-band single-chip receiver MMIC for FMCW(Frequency-modulated continuous-wave) radar is presented using $0.15{\mu}m$ GaAs pHEMT technology. The receiver MMIC consists of a 4-stage low noise amplifier(LNA), a down-converting mixer and a 3-stage LO buffer amplifier. The LNA is designed to exhibit a low noise figure and high linearity. A resistive mixer is adopted as a down-converting mixer in order to obtain high linearity and low noise performance at low IF. An additional LO buffer amplifier is also demonstrated to reduce the required LO power of the W-band mixer. The fabricated W-band single-chip receiver MMIC shows an excellent performance such as a conversion gain of 6.2 dB, a noise figure of 5.0 dB and input 1-dB compression point($P_{1dB,in}$) of -12.8 dBm, at the RF frequency of $f_0$ GHz, LO input power of -1 dBm and IF frequency of 100 MHz.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.4
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• pp.441-448
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• 2015

In this paper, a CPW-fed dual-band monopole antenna with two branch strips for WLAN(Wireless Local Area Networks) applications was designed, fabricated and measured. The proposed antenna is based on a CPW-feeding structure, and composed of two branch strips and then designed and tuned the length of two branch lines to obtained required frequencies bands. To obtain the optimized parameters, we used the simulator, Ansoft's High Frequency Structure Simulator(HFSS) and carried out simulation about parameters $L_5$, $L_8$, $W_3$, $W_5$, $W_9$. The proposed antenna is fabricated on the FR-4 substrate using the obtained parameters. The numerical and experiment results demonstrated that the proposed antenna obtained the -10 dB impedance bandwidth 1,095 MHz (1.57~2.665 GHz) for 2.4 GHz band and 1,680 MHz (4.99~6.67 GHz) for 5 GHz band satisfied requirement while simultaneously covering the WLAN bands. And characteristics of gain and radiation patterns are determined for WLAN operating bands.