• Journal of Korea Society of Industrial Information Systems
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• v.23 no.4
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• pp.23-31
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• 2018

This paper presented the implementation and design of the 2T-2R wireless HD video streaming systems over 1.7 GHz frequency band using 3GPP LTE-TDD standard on NI USRP RIO SDR platform. The baseband of the system used USRP RIO that are stored in Xilinx Kintex-7 chip to implement LTE-TDD transceiver modem, the signal that are transmitted from USRP RIO up or down converts to 1.7 GHz by using self-designed 1.7 GHz RF transceiver modules and it is finally communicated HD video data through self-designed 2x9 sub array antennas. It is that communication method between USRP RIO and Host PC use PCI express x4 to minimize delay of data to transmit and receive. The implemented system show high error vector magnitude performance above 32 dBc and to transmit and receive HD video in experiment environment anywhere. The proposed hybrid beam forming system could be used not only in the future 5G mobile communication systems under 6 GHz frequency band but also in the systems over 6 GHz frequency band like ones in mmWave frequency bands.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.156-162
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• 2016

This paper proposes a novel orthogonally-polarized dual-band switchable microstrip antenna. The proposed antenna consists of a perpendicular feeding network and an radiator with a PIN-installed H-shaped slot. When the states of one single PIN diode in H-slot are controlled by bias voltages, the controlled physical geometry of the H-slot determines the operation frequencies of switchable 1.80 GHz and 2.43 GHz for vertically polarized linear polarization and fixed 2.06 GHz for horizontally linear polarization. The implemented antenna experimentally demonstrates reconfigurable dual-band capability by means of controling the states of the PIN diode. The simulation and measurement results of the implemented antenna have been in good agreement with the reflection coefficients, realized antenna gains and far-field radiation patterns at each of the PIN diode states.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.1
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• pp.10-18
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• 2014

In this paper, we propose a new frequency reconfigurable dual-band antenna. By using an electronically compact eighth-mode substrate-integrated-waveguide(EMSIW) resonator, we have designed a compact antenna, which performs dual-band movement by additionally loading a complementary split ring resonator(CSRR) structure. The EMSIW and CSRR structures are designed to satisfy the bandwidths of 1.575 GHz(GPS) and 2.4 GHz(WLAN), respectively. We load the CSRR with a varactor diode to allow a narrow bandwidth and to enable the resonance frequency to continuously vary from 2.4 GHz to 2.5 GHz. Thus, we realize a channel selection function that is used in the WLAN standards. Irrespective of how a varactor diode moves, the EMSIW independently resonates so that the antenna maintains a fixed frequency of the GPS bandwidth even at different voltages. Consequently, as the DC bias voltage changes from 11.4 V to 30 V, the resonance frequency of the WLAN bandwidth continuously changes between 2.38 GHz and 2.5 GHz, when the DC bias voltage changes from 11.4 V to 30 V. We observe that the simulated and the measured S-parameter values and radiation patterns are in good agreement with each other.

• ETRI Journal
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• v.46 no.2
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• pp.218-226
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• 2024

This paper presents a novel circular fractal ring monopole antenna for ultra-wideband (UWB) hardware with dual band-notched properties. The proposed antenna consists of four crescent-shaped nested rings, a tapered feeding line at the front of the dielectric material, and a semicircular ground plane on the backside. In this design, the nested rings are used both as a radiation element and a band rejection element. The proposed antenna has a bandwidth of 9.03 GHz, which works efficiently in the range of 2.63 GHz-11.66 GHz with the dual notched bands of Worldwide Interoperability for Microwave Access (WiMAX) at 3.15 GHz-3.66 GHz and wireless local area network (WLAN) at 4.9 GHz-5.9 GHz, respectively. The antenna has a compact size of 20 mm × 30 mm × 1 mm (0.177 × 0.265 × 0.0084 λ0) and is implemented using a flame-retardant type 4 (FR4) material. It has a maximum gain of approximately 4 dB in its operating range, and experimental results support the simulation predictions with high accuracy. The findings of this study imply that the designed antenna can be utilized in UWB applications.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.40.1-40.1
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• 2021

Gwacheon National Science Museum(GNSM) has a 7.2m radio telescope, which is only one possessed by a science museum in Korea. In 2020, performance of the telescope had been improved in the way of a new antenna control system, receiver system, control and analysis software. New AC motors, limiters and encoders was installed and the new receive system can observe L-band(1.4GHz) and S-band(2.8GHz), L-band and Ka-band(33GHz) equipped previously. Using theses upgraded system we have developed educational programs, which are 'The Sun seen in radio' and 'The Universe seen in radio'. In the former, the sun is observed with several methods and show analysed data to participants. In the latter, various radio sources, the moon, supernova remnants and HI gas, and even signal from artificial satellites are observed. In addition, SETI demo data can be shown and demonstrates how to find artificial signal extraterrestrial intelligence could send.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.1
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• pp.25-30
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• 2017

In this paper, dual band patch antenna was designed using a CSRR structure with negative values permeability which inserted into the ground plane. We propose an antenna that can be used in dual band f1(1.53GHz) and f2(1.63GHz) for satellite communications by using the CSRR placed on the backside of feeding line, which is a negative shape of SRR. The proposed antenna can be arrayed using microstrip line and can be made smaller than conventional patch antenna. The fabricated antenna has the input reflection coefficient of -12.5dB and -14.5dB at f1 and f2, and the gain of 2dB and -0.8dB, respectively. and it was confirmed that the performance was sufficient in the dual-band.

• Journal of electromagnetic engineering and science
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• v.7 no.1
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• pp.42-46
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• 2007

This paper presents a linear amplitude equalizer developed to secure the linearity of the slope of the amplitude over the frequency band ranging $2\sim18\;GHz$. The circuit model is featured by the resistor placed between each pair of a transmission-line and a stub. The design includes finding the values of resistors and stubs to have the optimal linear slope and return loss performances. The measured data show the acceptable performances of the slope variation and return loss over $2\sim18\;GHz$.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.475-482
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• 2019

In this paper, we propose a triple band antenna for GPS / DCS / WLAN system. The proposed antenna has the characteristics required by considering the interconnection of two strip lines and various slits on the ground place. The total substrate size is $31mm(W1){\times}50mm(L1)$, thickness (h) 1.6 mm, and the dielectric constant is 4.4, which is made of $22mm(W7+W12+W8){\times}43mm(L4+L3)$ antenna size on the FR-4 substrate. From the fabrication and measurement results, bandwidths of 340 MHz (1.465 to 1.805 GHz), 480 MHz (2.155 to 2.635 GHz) and 1950 MHz (4.975 to 6.925 GHz) were obtained on the basis of -10 dB. Also, gain and radiation pattern characteristics are measured and shown in the frequency triple band as required.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.10
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• pp.1040-1049
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• 2014

In this paper, a quad-band antenna for DCS1800, PCS1900, WCDMA, WLAN and Mobile WiMAX application is proposed. The proposed antenna is a printed monopole structure, and consists of two rectangular ring-shaped radiating patches on the front side and two different size of L-shaped slots on the back side(ground plane). Two rectangular ring radiation patches are respectively resonant at 2 GHz and 3.5 GHz bands, and additional resonance is occurred at 5.3 GHz by the coupling effect between two ring patches. In addition, the optimized matching characteristic is obtained by controlling the gaps. Also, by adding two L-slots on the ground plane, additional resonant frequency band of 5.6 GHz is occurred. Finally the measured bandwidths of the proposed antenna below -10 dB return loss are 1,200 MHz(1.6~2.8 GHz), 800 MHz(3.2~4.0 GHz), 300 MHz(5.14~5.44 GHz), and 690 MHz(5.56~6.25 GHz). The radiation patterns have the omni-directional characteristic, and the measured antenna average gains at resonant bands are 0.86~4.07 dBi.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.5
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• pp.1-10
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• 1999

A low power concumption 2.4 GHz one-chip transceiver MMIC was designed and fabricated using $1.0\mu\textrm{m}$ ion-implantation MESFET process and packaged on a 24 lead SSOP. In the transmitter mode, it revealed conversion gain of 7.5 dB, output IP3 of -3.5 dBm, and noise figure of 3.9 dB at 2.44 GHz with 3.9 mA current consumption. In the receiver mode, it revealed voltage sensitivity of 6.5 mV/$\mu\$W with 2 .0 mA current consumption. Comparing the fabricated MMIC with the results of MMICs reported elsewhere, it was shown that the fabricated MMIC had good performance. The low power consumption 2.4 GHz transceiver MMIC is expected to be used for various applications such as wireless local area networks, wireless local loops and RFID tags in ISM-band.