• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.5
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• pp.123-127
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• 2017

This paper fabricated and analyzed the image rejection mixer that uses FET's channel resistance. It can be applied for capacity 64QAM that has 50MHz~90MHz of IF band, 8.17GHz of LO frequency and 8.08~8.12GHz of RF band. When IF input power is -20dBm and LO input power is 10dBm, RF output power is obtained -33.2dBm. In this case, conversion loss is 12.9dB, the suppression of 14.3dB for LO frequency and 10.4dB for image frequency. The result of two tone test shows great IMD characteristics with 51.7dBc.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.8
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• pp.41-46
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• 2012

A quadrature voltage controlled oscillator(QVCO) for X-band is presented in this paper. The QVCO has fabricated in Charted $0.13{\mu}m$ CMOS process. The QVCO consists of two cross-coupled differential VCO and two differential buffers. The QVCO is controlled by 4 bit of capacitor bank and control voltage of varactor. To have a linear quality factor of varactors, voltage biases of varactors are difference. The QVCO generates frequency tuning range from 6.591 GHz to 8.012 GHz. The phase noise is -101.04 dBc/Hz at 1MHz Offset when output frequency is 7.150 GHz. The supply voltage is 1.5 V and core current 6.5-8.5 mA.

• Journal of electromagnetic engineering and science
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• v.14 no.1
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• pp.31-35
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• 2014

An ultra-wideband (UWB) circular monopole antenna with a multiband-notched characteristic is proposed. The multiband-notched filter consists of three different sized folded slots, which are distinctly assigned for the notched band at the 3.5-GHz WiMAX, 5-GHz WLAN, and 8-GHz ITU bands. The proposed antenna results in a measured ${\mid}S_{11}{\mid}$ < -10 dB, which completely covers the UWB band (3.1 10.6 GHz) with three notched bands at 3.5, 5.5, and 8.0 GHz. The antenna yields an omnidirectional radiation pattern and high radiation efficiency.

• Journal of Electrical Engineering and Technology
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• v.8 no.1
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• pp.168-175
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• 2013

This paper presents compact dual-band WLAN filter and filter module. They were developed by embedding all of the passive lumped elements into a LTCC substrate. In order to reduce the size/volume of the filter and avoid EM parasitic couplings between the passive elements, the proposed filter was designed using a 3rd order Chebyshev circuit topology and J-inverter transformation technology. The 3rd order Chebyshev bandpass filter was firstly designed for the band-selection of the 802.11b and was then transformed using finite transmission zeros technologies. Finally, the dual-band filter was realized by adding two notch resonators to the 802.11b filter circuit for the band-selection of the 802.11a/g. The maximum insertion losses in the lower and higher passbands were better than 2.0 and 1.3 dB with minimum return losses of 15 and 14 dB, respectively. Furthermore, the filter was integrated with a diplexer to clearly split the signals between 2 and 5 GHz. The maximum insertion and minimum return losses of the fabricated module were 2.2 and 14 dB at 2.4 - 2.5 GHz, and 1.6 and 19 dB at 5.15 - 5.85 GHz, respectively. The overall volume of the fabricated filter was $2.7{\times}2.3{\times}0.59mm^3$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2011.10a
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• pp.76-78
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• 2011

In this paper, 0.8 GHz and 1.8 GHz dual-band antenna was designed for global system for mobile communications (GSM) and the Long Term Evolution (LTE) The proposed antenna was made using CST Microwave Studio 2009. My script antenna's substrate is Taconic TLY-5 and dielectric constant is 2,2 and has 1.0mm thickness with a compact design of the proposed antenna, Thus it shows that this proposed antenna can be used in Wireless Communication System.

• 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.

• Journal of Advanced Navigation Technology
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• v.22 no.1
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• pp.27-30
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• 2018

In this study, a 40 GHz band pass filter(BPF) employing a hair-pin structure has been designed, fabricated, and characterized for millimeter-wave wireless communication applications. Using the 3 dimensional(3-D) electromagnetic(EM) tool and design equations of the hairpin BPF, the BPF was desgned on the 5 mil-thick Duroid substrate(RT5880) with a relative dielectric constant (${\varepsilon}_r$) of 2.2. The tapping point (t) of the U-shape resonator in the input and output port has been determined using extracted an external Q-factor ($Q_e$). The coupling coefficients between the other resonators are calculated by adjusting the physical dimensions for the desired response of the BPF. The fabricated BPF was characterized using probing method on a probe station. Its measured center frequency(fc) and fractional BW are 41.6 GHz and 7.43 %, respectively. The measured return loss is below -10 dB at the pass band and the insertion loss is 3.87 dB. The fabricated BPF is as small as $9.1{\times}2.8mm^2$.

• Journal of the Korean Institute of Telematics and Electronics
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• v.13 no.5
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• pp.1-8
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• 1976

Microwave GaAs Metal Semiconductor Field effect Transistors (MESFET) with the gate-length of two micrometers are investigated. The scattering parameters of the transistors have been measured from 1GHz to 2GHz by Hp8545 Automatic network analyzer. From the measured data, an equivalent circuit is established which consists of an ntrinsic and. extrinsic transistor elements. In this paper, GaAb MESFET Amplifier is used in conjunction with conventional microstrip techniques to match into a 50 ohms high input/output impedances system. We found that Power gain is less than 8dB and VSWR is less than 1.5 in L-Band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.8
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• pp.827-833
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• 2002

In this paper, a microstrip array antenna for LMDS(Local Multipoint Distribution Service) receiver with corporate feeding network using Chebyshev polynomials is proposed to get the high gain and low side lobe level. The Chebyshev array method is proposed to design the corporate feeding network. LMDS uses 24~27 GHz microwave frequency band to send and receive broadband signals. Measured antenna shows 23.4 dBi gain, 24.96 GHz center frequency, -29.15 dB return loss and 1.2 GHz bandwidth.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.9
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• pp.1014-1020
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• 2009

In this paper, a novel UWB(Ultra Wide-band) antenna with suppressed band of IEEE 802.11a($5.15{\sim}5.825\;GHz$) WLAN was designed and fabricated by using SRR(Split Ring Resonator) with band rejection property. MWS(Micro-wave Studio) of CST company was utilized in the design stage. The antenna was fabricated on a substrate, Rogers 4003, with the thickness of 0.8 mm and relative permittivity of 3.38. The measured result shows that the proposed antenna has a good return loss below -10 dB and group delay below 1nsec over UWB communication band($3.1{\sim}10.6\;GHz$) except WLAN band. It also shows the omni-directional radiation pattern.