• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.2
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• pp.138-144
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• 2008

In this paper, we propose a novel single-feed dual-band circular polarization square patch antenna for GPS(global positioning system)/DMB(digital multimedia broadcasting) receiver. The proposed antenna has folded slots at the 4 corners and a diagonal slot at the center of the square patch. The measured -10 dB impedance bandwidths of the proposed antenna were 84 MHz ranging from 1.516 GHz to 1.600 GHz for the low frequency band(GPS) and 109 MHz ranging from 2.596 GHz to 2.705 GHz for the high frequency band(DMB). The measured peak linear antenna gains of the proposed antenna were 6.23 dBi at 1.575 GHz for GPS and 6.97 dBi at 2.642 GHz for DMB band.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.2
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• pp.27-32
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• 2018

In this paper, W-band transceiver module for compact radar has been designed and fabricated. Utilizing proposed microstrip-to-waveguide transition, the error between design and implementation is reduced. The proposed transition provides less than 1 dB insertion loss per transition and reliability for fabrication. In order to apply compact radar with dual-polarized monopulse directly, W-band transmitter with 28 dBm output power is designed and developed. Also, 6 channels of receiver module with low noise figure 13.5 dB and maximum 17 dBm input P1dB is developed. Proposed W-band transceiver module is expected compact radar application for dual-polarized monopulse signal processing system.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.8
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• pp.52-58
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• 2008

Ths paper describes the Dual-band switch which was proposed new structure that could improved the specification of broadband and designed by the optimized structure through simulation. The Dual-band switch with 2.4[GHz]/5.8[GHz] that can apply to 802.11a/b/g system that is commercialized present was studied to get a new structure with higher power, high isolation. The transmitter of switch was designed to operate a parallel switching element with stack structure of two FET. The receiver designed to have asymmetry structure that insert series FET in addition to basic serial/parallel FET. SPDT(Single Pole Double Throw) Tx/Rx FET switch is a device that can do switching from a port of input to two port of output. The fabricated SPDT switch has the characteristic of insertion loss of a below -3[dB] form DC to 6[GHz] and the isolation of a below -30D[dB](Rx mode).

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.66.1-66.1
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• 2012

We have developed superconducting mixer receivers for 129 GHz VLBI observation in Korean VLBI Network(KVN). The developed mixer has a radial waveguide probe with simple transmission line LC transformer as a tuning circuit to its 5 series-connected junctions, which can have 125-165 GHz as operation RF frequency. For IF signal path a high impedance quarter-wavelength line connects the probe to one end of symmetric RF chokes. DSB receiver noise of the mixer was about 40 K over 4-6 GHz IF band whereas we achieved about uncorrected SSB noise temperature of 70 K and better than 10 dB IRR in 2SB configuration with 8-10 GHz IF band. Insert-type receiver cartridges using the mixers have been assembled for all three KVN stations. On-site performance summary in commissioning phase is presented.

• Proceedings of the KIEE Conference
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• 2003.11b
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• pp.83-86
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• 2003

This paper is the research and development including the system design and the prototype system building of the wide-band digital autocorrelation spectrometer system for radio astronomy observation, which will be used as back-end signal processing unit of the Dual channel SIS receiver at Taeduk Radio Astronomy Observatory. So in this paper. we performed development of the high speed digitizing sampler, the circular memory buffer, and the correlator module for the 400MHz wide-band digital autocorrelator.

• JSTS:Journal of Semiconductor Technology and Science
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• v.2 no.2
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• pp.147-155
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• 2002

This paper describes RF front-end transceiver chipset for the dual-mode operation of PCS-Korea and IMT-2000. The transceiver chipset has been implemented in a $0.25\mutextrm{m}$ single-poly five-metal CMOS technology. The receiver IC consists of a LNA and a down-mixer, and the transmitter IC integrates an up-mixer. Measurements show that the transceiver chipset covers the wide RF range from 1.8GHz for PCS-Korea to 2.1GHz for IMT-2000. The LNA has 2.8~3.1dB NF, 14~13dB gain and 5~4dBm IIP3. The down mixer has 15.5~16.0dB NF, 15~13dB power conversion gain and 2~0dBm IIP3. The up mixer has 0~2dB power conversion gain and 6~3dBm OIP3. With a single 3.0V power supply, the LNA, down-mixer, and up-mixer consume 6mA, 30mA, and 25mA, respectively.

• Journal of information and communication convergence engineering
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• v.13 no.4
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• pp.235-240
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• 2015

A decimation chain for multi-standard reconfigurable radios is presented for 900-MHz and 1,900-MHz dual-band cellular standards with a data interpolator based on the Lagrange method for adjusting the variable data rate to a fixed data rate appropriate for each standard. The two proposed configurations are analyzed and compared to provide insight into aliasing and the signal bandwidth by means of a newly introduced measure called interpolation error. The average interpolation error is reduced as the ratio of the sampling frequency to the signal BW is increased. The decimation chain and the multi-rate analog-to-digital converter are simulated to compute the interpolation error and the output signal-to-noise ratio. Further, a method to operate the above-mentioned chain under a compressed mode of operation is proposed in order to guarantee continuous packet connectivity for inter-radio-access technologies. The presented decimation chain can be applied to LTE, WCDMA, GSM multi-mode multi-band digital front-end which will ultimately lead to the software-defined radio.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.59.2-59.2
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• 2017

The Submillimeter Array (SMA) has provided forefront capabilities for high spatial and spectral resolution observations at submillimeter wavelengths from its excellent site on Mauna Kea, Hawaii since 2004. The SMA has continuously enhanced its capability. It is now equipped with two receivers in the 1.3 mm band (Rx230/Rx240) and two in the 0.85 mm band (Rx345/Rx400). The total bandwidth available is 8+8 GHz (per receiver) in the dual band or polarization mode. To maintain a leading role in the ALMA era, the SMA project is now upgrading its receivers, IF signal transport and correlator system. The new wideband SMA - the wSMA - will provide the instantaneous coverage of 56 GHz. In this presentation, I will introduce the latest status of the SMA, upgrade plan to the w-SMA, the possible science cases with the w-SMA, and the roles of the w-SMA in the ALMA era.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.221-232
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• 2000

A Gunn waveguide-oscillator, mechanically tunable from 60 to 70 GHz, has been developed for use as a local oscillator(LO) is millimeter radio telescope. Disc size, post size and characteristics of Gunn diode have an effect on the frequency tuning characteristics of Gunn oscillator. In this paper we report experimental results and design criteria for a wideband tunable Gunn oscillator. The developed Gunn oscillator has been used in the 100/150 GHz band dual channel receiver for the Taeduk Radio Astronomy Observatory.

• The Bulletin of The Korean Astronomical Society
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• v.24 no.1
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• pp.50-50
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• 1999