• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.12
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• pp.22-29
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• 2009

In this paper, we developed the 200-Watts SSPA(Solid State Power Amplifier) for the X-band pulse compression solid state radar. The developed X-band SSPA is consists of 3-stage CSA(Corporate Structured Amplifier) modules in pre-amplifier stage, driver-amplifier stage and main-power amplifier stage. The main-power amplifier stage of SSPA designed by balanced type using GaN HEMT with enough power and gain to generate power more than 200-Watts in X-band. The developed SSPA has performance with more than total gain 59dB and output power 200-Watts in condition of frequency range 9.2-9.6GHz, pulse period 1msec, pulse width 100usec and duty cycle 10%. The developed SSPA in this paper can apply to high quality solid state radar system with pulse compression technique.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.3
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• pp.25-31
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• 2003

In this paper, we proposed a novel compact microstrip lowpass filter with an ultra-wide stopband and a sharp cutoff frequency response. To improve the cutoff response of the conventional filter, the coupling effect between two open stubs is used. The slot on the ground with conventional shunt open stubs plays an important role of increasing the stopband at a high frequency. The combination of these structures gives the filter the characteristics of an ultra-wide stopband with a prominent cutoff sharpness. The fabricated microstrip lowpass filter with the size of 19.2 mm $\times$ 14.9 mm has -3 dB cutoff frequency at 1.1 GHz and -20 dB stopband from 1.5 GHz to over 30 GHz. The insertion loss is less than -0.15 dB in the passband.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.5
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• pp.851-856
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• 2006

This paper studies about design of a transceiver using a single PLL. The transceiver has bandwidth of $424.7\sim424.95MHz$ and the communication method used 21 channels 12.5 KHz channel bandwidth and FSK modulation/demodulation method. Also, we designed low power wireless transceiver for data transmission using a single PLL. Finally, the transceiver set achieves the following characteristics : 8.15dBm output power, 45.97dBc spurious property.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2000.10a
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• pp.172-175
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• 2000

본 논문에서는 무선마이크용 특정소출력무선기기의 송수신단을 설계하고 제작하여 특성을 측정하였다. 무선마이크용 특정소출력무선기기의 주파수 대역 740.000~752.000MHz를 사용하였고, 점유주락수대폭의 허용치 200kHz, 최대주파수편이 $\pm$75kHz를 만족하도록 설계하였다. PLL Synthesized, 주파수 변조, Dual Conversion 방식을 사용하였으며 Compander Type은 2:1이다. 설계된 무선마이크 시스템의 출력은 10mW이하이고, 50-20,000Hz의 주파수 응답을 가지며 Hi-fi Audio를 전송할 수 있다. 송수신단의 Total Harmonic Distortion 은 1.5% 이하이다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.698-701
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• 2008

본 논문에서는 상용소자의 특성과 상향변환기의 모듈에 소요되는 링크전력을 비교 분석하여 Ka-band VSAT UPCONVERTER를 설계하였다. $30GHz{\sim}31GHz$대역에서 2W 출력신호를 나타내기 위하여 상향변환시스템은 IF증폭단, 감쇄기, 믹서단, 대역통과필터 및 2W 전력증폭단으로 구성시켰으며 상용MMIC를 이용하여 설계된 상향변환모듈은 $6.29dBm{\sim}7.88dBm$의 출력전력, 이득은 $23.19{\sim}28.15dB$을 Cain flatness는 4.95dB를 나타내었다. 최종단의 전력증폭기는 $33.75{\sim}34.96dBm$의 출력전력을 나타내었으며 이득은 $38.5{\sim}41.98dB$로 측정되었다.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.18 no.6
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• pp.233-240
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• 2019

In this paper, due to the development of 5G communication technology, an antenna capable of covering both LTE and 5G bands is currently needed. In addition, we designed and manufactured a single feed antenna for the integrated public network (LTE) and 5G frequency dual band cover to satisfy the frequency bandwidth of more than 10% in each band. The antenna designed by adopting the dipole of the basic dipole antenna in a planar structure is a form in which the radiating element is vertically extended at all of the 700 MHz antennas and folded into a 'ㄷ' shape. In addition, the radiating element of the 700MHz band serves as a reflector of the 3.5GHz band radiating element. As a result, the 700 MHz band -10 dB bandwidth 104 MHz(14.8%) and 3.5 GHz band -10 dB bandwidth 660 MHz(18.8%) were obtained and the radiation pattern characteristic resulted in gains of 8.46 dBi, beam width E-plane 55°, H-plane 81° and 3.5 GHz bands 6.14 dBi, beamwidth E-plane 79°, H-Plane 49°.

• Journal of IKEEE
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• v.21 no.3
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• pp.219-226
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• 2017

This paper was studied the double-band monopole antenna design with Mu-negative metamaterial unit cell, which operates at 700MHz and 2.45GHz band. Mu-negative unit cell made of the interdigital capacitor structure to operate a double-band antenna by inserting it into an antenna radiator unit. In addition, the parasitic conductor is implemented on the back side of the antenna radiation part, so that the resonance point of the antenna can be controlled and the bandwidth is improved. Finally, we implemented an antenna operating in the 750MHz UHD band and the 2.45GHz WiFi band. The designed antenna has a size of $200{\times}100mm^2$. Experimental results show that the 8dB bandwidth and gain characteristics at 750MHz band are 320MHz(42.7%), 5.28dB, 6dB bandwidth and gain at 2.45GH are 540MHz (21.6%), -0.46dB. From the experimental results, we confirmed that the resonance point with theoretical value is in agreement with experimental value, and the radiation patterns are have the omnidirectional characteristic in both bands.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.7
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• pp.75-79
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• 2004

In this paper, a single plane wide band microstrip antenna for integrated circuit as MMIC and LTCC is designed and fabricated. A new configuration for a wide band microstrip antenna with omni-directional pattern is proposed. This antenna consists of two rectangular folded dipoles, which are fed by a coplanar waveguide(CPW). It was effected stabilization ground that a signal plane of CPW feed have been limited ground plane. Therefore, a ground plane of folded structure should be extended outside folded antenna in this research. The characteristics of the proposed antenna were analyzed by using an FDTD methods. The return loss and radiation patterns were simulated and measured. The proposed antenna is get 120MHz bandwidth of PCS band and 250MHz bandwidth of IMT2000 band, used ISM band.

• Journal of Navigation and Port Research
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• v.27 no.5
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• pp.505-511
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• 2003

In this paper, a driving amplifier stage with 1 Watt output has been designed and fabricated, which is operating at UHF band( 470 ∼ 806 MHz) for digital TV repeater. In the driving amplifier stage, preamplifier and 1 Watt unit amplifier are integrated by one electric substrate which is 2.53 in dielectric constant and 0.8 mm thickness. When the driving amplifier stage is flown by bias voltage of 28 V DC and current of 900 mA. it has the gain of more than 53.5 dB. the gain flatness of $\pm$0.5 dB and return loss of less than -15 dB in 470 ∼ 806 MHz. Also, when two signals at 2 MHz frequency interval are input port into the driving amplifier stage with 1 Watt output, it resulted in excellent characteristics to designed specification with showing intermodulation distortion characteristics of more than 48 dBc.