• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.175-178
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• 2002

In This paper, a microstrip slot antenna is designed and fabricated for wireless LAN at 5.8GHz band. The microstrip slot antenna is fed by CPW and formed the inductively slot and tile capacitively slot. To obtain wideband, the inductively slot is designed at 5.3GHz and the capacitively slot is designed at 5.8GHz. Resonant frequency of the fabricated microstrip slol antenna is 5.BCD, the bandwidth for VS%<1.5 is 29% and the gain is 4.6dB. The 3-dB beamwidth of E-plane and H-plane is 80 “ and 120 ”, respectively

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.748-754
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• 2000

A novel single feed wide band CP stacked microstrip antenna using crossed slots has been designed, fabricated and measured. For the single rediating element the designed 10dB return loss bandwidth is 34.5%99.45~13.54 GHz), 3dB axial ratio bandwidth is 18.7%(11.17~13.39GHz), and 6 dB gain bandwidth is 29%(10.21~13.64GHz). For the 2$\times$2 array designed using a sequential rotation method, the 10dB return loss bandwidth is 35.9%(9.69~13.94GHz), 3dB axial ratio bandwidth is 34.6GHz (9.93~14.03GHz), and 6dB gain bandwidth is 27.4%(10.35~13.6GHz). For the fabricated 8$\times$8 array antenna, the 10dB return loss bandwidth is 27.3%(10.17~13.41GHz), 3dB axial ratio bandwidth is 27.9GHz(10.1~13.4GHz), and the radiation pattern is good agreement with theory. This antenna can be used for broadband applications for communications or broadcasting in Ku band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.10A
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• pp.1065-1071
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• 2007

In this paper, in order to research spectrum usage efficiency in urban canyon environment at the microwave band, measurement and channel capacity analysis of multi-antenna technology is described. The measurement data obtained from 3 - 4 stories building area used and the propagation characteristics at the 3.7 and 8GHz band are analysed and compared. In case of $2{\times}2$ MIMO, channel capacities of 3.7 and 8 GHz band are calculated to 9.1 bps/Hz and S bps/Hz and in case of $4{\times}4$ MIMO, 21 bps/Hz and 12.5 bps/Hz respectively. Considering the coverage, SNR and channel capacity in urban environment, MIMO propagation characteristics of 3.7 GHz are more predominate than those of 8 GHz.

• Journal of IKEEE
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• v.17 no.3
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• pp.385-392
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• 2013

In this paper, microstrip antenna to enhance the isolation between transmitting port and receiving port under the proximity objects is proposed, and applied to the Doppler radar sensor working at 5.8GHz ISM band which detects vital signals of a human body. Two 3dB quadrature hybrids are placed around radiation patch to form a balanced structure between transmitting port and receiving port, such that it consistently provides enhanced Tx/Rx isolation and excellent return loss over nearby objects. It is theoretically analyzed and simulated to verify the validity of the proposed application. The fabricated antenna that is 2mm away from the human body, has more than 16 dB return loss and at least 30dB isolation over ISM frequency band of 5.8GHz.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1638-1639
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• 2011

본 논문에서는 초소형 무선 USB 동글 장치를 위한 광대역 접힌(folded) 모노폴 안테나를 제안하였다. 제안된 안테나는 CPW 급전으로부터 삼지창 형상의 선로를 적용하여 광대역 특성을 구현하였다. 최종 설계된 안테나의 크기는 $16{\times}44.8{\times}3.5\;mm^3$이며, low-profile의 무선 USB 동글용 안테나에 적합하다. 제안된 안테나는 $S_{11}$ < -10 dB 기준으로 2.28~10.8 GHz의 공진 주파수 대역을 가지므로 WiBro (2.3~2.4 GHz), Bluetooth (2.4~2.484 GHz), WiMAX (2.5~2.7 GHz, 3.4~3.6 GHz), satellite DMB (2.605~2.655 GHz), 802.11b/g/a WLAN (2.4~2.485 GHz, 5.15~5.825 GHz), UWB(3.1~10.6 GHz)의 무선 대역을 지원 할 수 있다. 측정된 평균 이득의 범위는 -3.41 dBi 에서 -0.84 dBi 이다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.9
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• pp.749-755
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• 2017

In this paper, a wideband microwave absorber for X-band(8~12 GHz) applications is proposed. The structure of the proposed absorber unit cell consists of a resonator with a slot and slit, a backing ground plate, and a Taconic RF-30(${\varepsilon}_r=3$, $tan{\delta}=0.0014$) substrate with a dimension of $8.5{\times}8.5{\times}0.5mm^3$. The proposed absorber has a dual resonance at 9.83 and 10.37 GHz. To demonstrate the operating principle of the proposed absorber structure at each resonance frequency, the simulated current distributions on the unit cell are analyzed. To verify the performance of the proposed absorber, a prototype absorber was fabricated with a planar array of $20{\times}20$ unit cells. The measured results exhibit two absorptivity peaks stronger than 99 % and full-width at half-maximum(FWHM) bandwidth of 1.1 GHz(9.51~10.61 GHz).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.10B
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• pp.1701-1706
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• 2000

In this work a 38 GHz hybrid 2-stage power amplifier module using GaAs pHEMTs and waveguide to microstrip transitions has been successfully developed. A 10 mil thickness duroid substrate was use for fabrication of the power amplifier and the 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 29 dBm output power(P1.5dB), 7,2 dB associated gain and 11.2% power-added efficiency(PAE) at 36.8-38.5 GHz.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.6
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• pp.116-126
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• 2008

This paper describes the Dual-band WLAN transmitter with 2.4[GHz], 5[GHz]. Dual-band WLAN transmitter was designed at 2.4[GHz] and 5[GHz]. The Dual-band WLAN transmitter has a amplifier which operate at 2.4[GHz] and 5[GHz] frequency and two VCO(Voltage Controlled Oscillator) or VCO has a wide scope of frequency. these problem cause a size and a power consumption, The Dual-band WLAN transmitter module was proposed to solve these. the transmitter was designed to get output signals of IEEE 802.11a's 5.8[GHz] band signal using frequency multiplication way or to act a amplifier about the 2.4[GHz] band signal of IEEE 802.11b/g, according to inputed frequency and bias voltage that a eve using single transmission block. The output spectrum get the improved specification of ACPR of 4[dB], 6[dB], 16[dB] at +11[MHz], +20[MHz], +30[MHz] offset of center frequency compared to no linearization, was satisfied to transmit spectrum mask of IEEE 802.11a wireless Lan.

• 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.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.6
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• pp.512-520
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• 2016

In this paper, a miniaturized frequency selective surface(FSS) for bandstop operation that provides stability for an angle of incidence and polarization is presented. The proposed miniaturized FSS has the unit cell of hexagonal structure with triangular loops and size of the unit cell is $0.081{\lambda}{\times}0.081{\lambda}$ at 2.5 GHz operating frequency, which is very small compared to operating wavelength. In addition, unlike the conventional design, which requires complicated design parameters, the proposed FSS is easily expanded to the desired operating frequency for 2~8 GHz, by controlling the specific design parameters. To validate the simulation results, the FSS structures having different operating frequencies, 2.5 GHz, 5 GHz and 8.2 GHz were designed, fabricated and measured. The comparisons between the simulation and the measured results show good agreement. The proposed miniaturized FSS can provide better frequency stability for different incidence angles and polarizations.