• Journal of Advanced Navigation Technology
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• v.26 no.6
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• pp.516-521
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• 2022

In this paper, a compact 4-bit chipless RFID(radio frequency identification) tag using a modified ELC(electric field-coupled inductive-capacitive) resonator and multiple slot resonators is proposed. The modified ELC resonator uses an interdigital-capacitor structure in the conventional ELC resonator to lower the resonance peak frequency of the RCS. The multiple slot resonators are designed by etching three slots with different lengths into an inverted U-shaped conductor. The resonant peak frequency of the RCS for the modified ELC resonator is 3.216 GHz, whereas those of the multiple slot resonators are set at 4.122 GHz, 4.64 GHz, and 5.304 GHz, respectively. The proposed compact four-bit tag is fabricated on an RF-301 substrate with dimensions of 50 mm×20 mm and a thickness of 0.8 mm. Experiment results show that the resonant peak frequencies of the fabricated four-bit chipless RFID tag are 3.285 GHz, 4.09 GHz, 4.63 GHz, and 5.31 GHz, respectively, which is similar to the simulation results with errors in the range between 0.78% and 2.16%.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.1
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• pp.103-107
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• 2024

This paper is a study on a triangle patch antenna using a rectangle slot and strip conductor. The length and spacing of the slot were adjusted to confirm the characteristics of the triangle patch antenna with rectangle slot, and the area and shape of the radiation patch were changed to triangle, rectangle, and hexagon for impedance matching. The HFSS simulator was used to check the antenna parameter characteristics, and the antenna size was 26 mm ×26 mm. In this proposed antenna, the simulation frequency range with VSWR of 2 or less was 5.27 to 6.24 GHz. The bandwidth was 970 MHz. The frequency range of the fabricated antenna was 5.24 to 6.38 GHz, and the bandwidth 1140 MHz. The maximum radiation gain is 5.01 dBi. It was confirmed that all radiation patterns had directional characteristics.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2002.02a
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• pp.358-361
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• 2002

The millirneterwave high-T$_{c}$ superconducting(HTS) down-converter sub-system with the HTS/III-V integrated mixer as the central device is demonstrated first. The constituent components of HTS down-converter sub-system such as a single balanced type integrated mixer with rat-race coupler, a cavity type bandpass filter (26 GHz), and a HTS planar lowpass filter(1 GHz), semiconductor LNA and IF-power amplifier, a driving electronic module for A/D converter, and a Stirling type mini-cooler module were combined into an International stand- and rack of 19-inch. From the RF(-61 dBm, 26.5GHz)and LO signal(-1 dBm, 25.6 GHz), IF signal(0dBm, 0.9 GHz) agreed with simulated results is obtained.d.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.650-656
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• 2016

Voltage controlled oscillator (VCO) is widely used circuit component in high-performance microprocessors and modern communication systems as a frequency source. In present work, VCO designs using the different combination of NAND gates with three transistors and CMOS inverter are reported. Three, five and seven stages ring VCO circuits are designed. Coarse and fine tuning have been done using two different supply sources. The frequency with coarse tuning varies from 3.31 GHz to 5.60 GHz in three stages, 1.77 GHz to 3.26 GHz in five stages and 1.27 GHz to 2.32 GHz in seven stages VCO respectively. Moreover, for fine tuning frequency varies from 3.70 GHz to 3.94 GHz in three stages, 2.04 GHz to 2.18 GHz in five stages and 1.43 GHz to 1.58 GHz in seven stages VCO respectively. Results of power consumption and phase noise for the VCO circuits are also been reported. Results of proposed VCO circuits have been compared with previously reported circuits and present circuit approach show significant improvement.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.2
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• pp.303-312
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• 2009

In this paper, we design and fabricate a disk sector antenna fed by CPW fur UWB communications. Also, we insert a rectangular slit on the arc-edge of the disk sector antenna. Then, the antenna has the directivity of E-면. In order to design the antenna, the input impedance is matched with the feed line of $50{\Omega}$ as varying the physical antenna parameters, which are the radius, the flare angle of disk sector, the length of ground, and the length of ground comer near by feed tine. Dimension of the antenna designed for UWB communication is $72mm{\times}26mm$ and bandwidth through computer simulation is $3{\sim}13GHz$. From the measured results, the bandwidth is $1.98{\sim}11GHz$. Return loss and gain of the fabricated antenna are -50.38dB, 1.34dBi at 3.5GHz, -12.27dB, 3.35dBi at 5.5GHz, -23.2dB, 3.8dBi at 8GHz and -16.17dB, 5.2dBi at 10GHz, respectively.

• Journal of Satellite, Information and Communications
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• v.9 no.3
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• pp.53-58
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• 2014

The global automotive radar is regulated to use the 22GHz~26GHz band. However, it plans to move to the 77~81GHz band of a broadband radar in the millimeter wave for the high resolution of pedestrian sensing and blind spot. On the other hand, the 71~275GHz band is regulated to use a radio astronomy service. The interference is predicted between an automotive radar and a radio astronomy service. Therefore, this paper analyzed the interference impact of the automotive radar on the radio astronomy service and then obtained separation distance for the protection of the radio astronomy service.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.1
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• pp.43-47
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• 2015

In this work, a broadband microstrip (MSL) - to - waveguide (WR12) transition has been presented for millimeter-wave module applications. For improvement of a bandwidth, the radial MSL electrical-probe is designed on the low-loss organic dielectric substrate. The designed and tested characteristics of the proposed transition are characterized in terms of an insertion and return loss. Considering the loss contribution of the cable adapter and waveguide transition for the measurement, the proposed transition loss can be analyzed as -1.88 and -2.01 dB per a transition at 70 and 80 GHz, respectively. The bandwidth of the proposed transition for reflection at -10 dB is 26 GHz at all test frequencies from 67 to 95 GHz. Compared to the state-of-the-art results, improvement of 8.3 % is achieved for the operation bandwidth.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.26 no.4
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• pp.871-883
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• 2016

It has been steadily increasing to use a wireless keyboard via Radio Frequency which is the input device. Especially, wireless keyboards that use 2.4 GHz frequency band are the most common items and their vulnerabilities have been reported since 2010. In this paper, we propose a 2.4 GHz wireless keyboard keystroke analysis and injection system based on the existing vulnerability researches of the Microsoft 2.4 GHz wireless keyboards. This system is possible to control on the remote. We also show that, via experiments using our proposed system, sensitive information of user can be revealed in the real world when using a 2.4 GHz wireless keyboard.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.4
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• pp.131-136
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• 2008

Two Ka-band 3-stage power amplifiers were designed and fabricated using $0.18-{\mu}m$ CMOS technology. For low loss matching networks for the amplifiers, two substrate-shielded transmission line structures, having good modeling accuracy up to 40 GHz were used. The measured insertion loss of substrate-shielded microstrip-line (MSL) was 0.5 dB/mm at 27 GHz. A 3-stage CMOS amplifier using substrate-shielded MSL achieved a 14.7-dB small-signal gain and a 14.5-dBm output power at 27 GHz in a compact chip area of 0.83$mm^2$. The measured insertion loss of substrate-shielded coplanar waveguide (CPW) was 1.0 dB/mm at 27 GHz. A 3-stage amplifier using substrate-shielded CPW achieved a 12-dB small-signal gai and a 12.5-dBm output power at 26.5 GHz. This results shows a potential of CMOS technology for low cost short-range wireless communication components and system.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.4
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• pp.281-286
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• 2007

In this paper, sub-circuits for 24 GHz phase locked 100ps(PLLs) using $0.5{\mu}m$ SiGe HBT are presented. They are 24 Ghz voltage controlled oscillator(VCO), 24 GHz to 12 GHz regenerative frequency divider(RFD) and 12 GHz to 1.5 GHz static frequency divider. $0.5{\mu}m$ SiGe HBT technology, which offers transistors with 90 GHz fMAX and 3 aluminum metal layers, is employed. The 24 GHz VCO employed series feedback topology for high frequency operation and showed -1.8 to -3.8 dBm output power within tuning range from 23.2 GHz to 26 GHz. The 24 GHz to 12 GHz RFD, based on Gilbert cell mixer, showed 1.2 GHz bandwidth around 24 GHz under 2 dBm input and consumes 44 mA from 3 V power supply including I/O buffers for measurement. ECL based static divider operated up to 12.5 GHz while generating divide by 8 output frequency. The static divider drains 22 mA from 3 V power supply.