• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.15 no.2
• /
• pp.145-151
• /
• 2004

This paper presents a fully integrated 5 GHz band low phase noise LC tank VCO. The implemented VCO is tuned by integrated PN diodes and tuning rage is 5.01∼5.30 GHz with 0∼3 V control voltage. For improved phase noise performance, a LC filtering technique is adapted. The measured phase noise is -87.8 dBc/Hz at 100 kHz offset frequency and -111.4 dBc/Hz at 1 MHz offset frequency which is excellent performance. Moreover phase noise is improved by 5 dB after employing the LC filter. It is the first experimental result in field of InGaP/GaAs HBT VCOs. The figure of merit of the fabricated VCO with LC filter is -172.1 dBc/Hz. It is the best result among 5 GHz InGaP HBT VCOs. Moreover this work shows lower DC power consumption, higher output power and more fixed output power compared with previous 4, 5 GHz band InGaP HBT VCOs.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.12C
• /
• pp.268-272
• /
• 2001

In this thesis, PLVCO(Phase Locked Voltage Controlled Oscillator) using 24.42 GHz voltage controlled hair-pin resonator oscillator, Sequency divider, buffer amplifier, -10 dB directional coupler and phase detector is designed and fabricated for B-WLL. The PLVCO shows the oscillator output power of 16.5 dBm at 24.42 GHz, and phase noise of -76.3 dBc/Hz at 1001:Hz offset, -72.8dBc/Hz at 10 kHz offset from fundamental frequency.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
• /
• v.3 no.2
• /
• pp.51-60
• /
• 2004

In this paper, 8-channel multiplexer with 100GHz channel spacing is fabricated. The 8-channel multiplexer is fabricated by connecting three cascaded Mach Zehnder Interferometer (MZI) of optical fiber type, and each interferometer has the wavelength interval of 100GHz, 200GHz and 400GHz, respectively. furthermore, to acquire uniform insertion loss, it is fabricated by using Wavelength Flatten Coupler (WFC) in which the variation of insertion loss is low. Especially, the variation of wavelength interval in the output is explicitly simulated as a function of optical path difference, and the wavelength coupling process along with cascaded connection is discussed. $CO_2$ laser to adjust precisely the wavelength. In summary, The prototype composed by eight cascaded MZI has an insertion loss of 2.1dB, the bandwidth of 0.8nm at 5.5dB point, and channel crosstalk of 25dB Furthermore, the loss dependent on polarization is measured as 0.06dB.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.16 no.4
• /
• pp.27-30
• /
• 2016

in this paper, to improve the narrow bandwidth problem of the microstrip antenna for WLAN and WiFi dual band array antenna was designed to satisfy the bandwidth of 3.6GHz and 5.2GHz it contained with IEEE 802. 11. The substrate of proposed microstrip array antenna is FR-4(er=4.3) and $25mm{\times}45mm{\times}0.8mm$ size and thickness t=0.035mm, and the simulation was used for CST Microwave Studio 2014. input return loss compared -10dB less than operates at and when gain 3.6GHz 2.516dB, 5.2GHz showed the results of 3.581dB. the antenna designed to be miniaturized and the be used in electronic devices such as mobile phone.

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

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.5
• /
• pp.598-605
• /
• 2012

In this paper, a multi-layer dual-band bandpass filter using aperture-coupling is proposed. Two coupling paths are formed with the two apertures which exist between two dual-mode resonators. The coupling coefficients can be adjusted without changing the shape of resonators. The bandwidth of the second passband can be adjusted without affecting the bandwidth of the first passband using the size of an aperture between stubs of the dual-mode resonator. The aperture coupling mechanism is theoretically analysed. The dual-mode bandpass filter for the 2.4 GHz WLAN, 3.5 GHz WiMax was designed and fabricated. The fabricated filter shows centered 2.45 GHz and 3.5 GHz with 9 % and 8 % of the bandwidth.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.49 no.8
• /
• pp.41-46
• /
• 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 the Earthquake Engineering Society of Korea
• /
• v.6 no.1
• /
• pp.13-21
• /
• 2002

Frequency bandwidth has been combined to determine adequate frequency bandwidth which is necessary for nondestructive testing when using inverse synthetic aperture radar(ISAR). For imaging inside of concrete specimens using radar, the principles of radar and signal processing are discussed. Experimental data obtained from radar measurement of three different concrete specimens at two different frequency bandwidths of 2∼3.4 GHz, 3.4∼5.8 GHz and these two frequencies are combined to obtain improved imagery. A signal processing scheme has been implemented to visualize inside concrete specimens. The influence of frequency bandwidth was analyzed in nondestructive testing by changing frequency bandwidth for concrete specimen.

• Journal of Korea Society of Digital Industry and Information Management
• /
• v.9 no.4
• /
• pp.43-49
• /
• 2013

In this paper, it is designed inverted triangle structural planar monopole antenna with edge and rectangle slot for UWB(Ultra Wide Band) communication (3.1~10.6 GHz) and researched in about 5.8 GHz notch structure to prevent interference between UWB systems and existing wireless systems for using Wi-Fi service. The antenna have broadband property structurally through inverted triangle structural planar monopole which have edge. and rectangle form addition planned notch slot of 1 mm and height 0.1 mm. Monopole and ground of proposed antenna exist on coplanar plane, and excite as CPW. It used FR4 epoxy dielectric substrate of ${\varepsilon}r$=4.4, and the size is $20{\times}20{\times}1.6$ mm dimension. The measured results that are obtained return loss under -10 dB through 3.1~10.6 GHz(7.5 GHz) without Wi-Fi bandwidth and maximum gain of 8.44 dBi at E-plane. Radiation pattern is about the same that of dipole antenna at all frequency. And using notch slot and it will be able to confirm the quality which becomes notch from 5.8 GHz which are a radio LAN frequency range.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.12
• /
• pp.8643-8648
• /
• 2015

In this paper presents the design and demonstrate 8 W 3-stage HPA(High Power Amplifier) MMIC(Monolithic Microwave Integrated Circuits) for Ka-band down link satellite communications payload system at 19.5 GHz ~ 22 GHz frequency band. The HPA MMIC consist of 3-stage GaN HEMT(Hight Electron Mobility Transistors). The gate periphery of $1^{st}$ stage, $2^{nd}$ stage and output stage is determined $8{\times}50{\times}2$ um, $8{\times}50{\times}4$ um and $8{\times}50{\times}8$ um, respectively. The fabricated HPA MMIC shows size $3,400{\times}3,200um^2$, small signal gain over 29.6 dB, input matching -8.2 dB, output matching -9.7 dB, output power 39.1 dBm and PAE 25.3 % by using 0.15 um GaN technology at 20 V supply voltage in 19.5~22 GHz frequency band. Therefore, this HPA MMIC is believed to be adaptable Ka-band satellite communication payloads down link system.