• Journal of Advanced Navigation Technology
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• v.13 no.2
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• pp.244-251
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• 2009

In this paper, a compact slot antenna for 2.4GHz ISM band applications has been designed. The folded slot with some additional meander sections are used in the design of the antenna within the restricted PCB space. The operating frequency band and the fractional bandwidth of the antenna is about 2.32~2.58 GHz and 11%, and the radiation patterns within the operation bandwidth are almost same. Also, the radiation efficiency and gain of the antenna is more than 49% and 1.2 dBi respectively. To check the validity of the design result, the measurement and simulation results are compared and presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.6
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• pp.1045-1049
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• 2001

Wireless LANs in the 2.4 ㎓ ISM- band create a new Electromagnetic Compatibility (EMC) problem. We investigated the interference characteristics between such wireless LANs in the case of identical systems, systems with different technical parameters for modulation and demodulation, and using a Gaussian noise source as a disturbance source. Experimental results show that higher throughput is obtained when adjacent wireless LANs use different systems, and that interference characteristics can be evaluated experimentally using a Gaussian noise source. Calculated BER characteristics for the interference agree with experimental measurements, indicating that this calculation method can be used for the design of the wireless LAN network to avoid interference. It is possible to construct an efficient wireless LAN network by combining different wireless LAN systems.

• Journal of Advanced Navigation Technology
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• v.24 no.2
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• pp.107-114
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• 2020

A power amplifier of 2.4 GHz ISM band is designed to implement a transmitter system. High efficiency amplifiers can be implemented as class E or class F amplifiers. This study has designed a 20 W high efficiency class E amplifier that has simple circuit structure in order to utilize for the ISM band application. The impedance matching circuit was designed by class E design theory and circuit simulation. The designed amplifier has the output power of 44.2 dBm and the power added efficiency of 69% at 2.45 GHz. In order to apply 30 dBm input power to the designed power amplifier, voltage controlled oscillator (VCO) and driving amplifier have been fabricated for the input feeding circuit. The measurement of the power amplifier shows 43.2 dBm output and 65% power added efficiency. This study can be applied to the design of power amplifiers for various wireless communication systems such as wireless power transfer, radio jamming device and high power transmitter.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.2
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• pp.104-109
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• 2020

In this paper, we proposed a miniaturized folded inverted F antenna with ISM-band (center frequency : 447 MHz) for mounting in intelligent parking sensor. First, to mount the antenna in the intelligent parking sensor module (72 mm × 70 mm) with limited size, a folded inverted F antenna was designed at low frequency 447 MHz (wavelength λ : 670 mm) of the ISM-band. As a result, it resonates in the ISM band and obtains suitable characteristic with a -10 dB bandwidth of 13 MHz (2.9%). In addition, the H-plane pattern by the vertical and horizontal elements represents the omni-directional patterns from which the null point is removed, and the E-plane has directivity in a specific direction. Finally, it is suitable as and antenna for vehicle management in parking lots.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.2 s.105
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• pp.198-206
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• 2006

The GFSK Transceiver of 400 MHz ISM band for data communication is designed and fabricated. To reduce the occupied bandwidth of transmitted signal, the GFSK modulation is selected. The measured results of fabricated transceiver show the data rate of 2,400 bps at 8.5 kHz bandwidth, frequency deviation of less than ${\pm}3\;kHz$, sensitivity of -107 dBm at SINAD of 20 dB, BER of less than $1.8{\times}10^{-3}$ at -110 dBm input power. The fabricated transceiver is satisfied with the regulation of radio wave and has the good performance.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.4
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• pp.886-893
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• 2004

In this paper, active resonator oscillator using active band pass filter with gain, active resonator with negative resistance using transistor(agilent ATF-34143) is designed and fabricated. Proposed active resonator oscillator for local oscillator in ISM band(5.8GHz) is designed with 5.5 GHz oscillation frequency. Designed active resonator oscillator implemented on the substrate which has the relative dielectric constant of 3.38, the height of 0.508mm, and metal thickness of 0.018mm. Active resonator oscillators using active band pass filter with gain show the oscillation frequency of 5.6GHz with the output power of -2dBm and phase noise of -81dBc/Hz at the offset frequency of 100kHz. Active resonator oscillators active resonator with negative resistance show the oscillation frequency of 5.6, 5.8GHz with the output power of -4dBm and phase noise of -91dBc/Hz at the offset frequency of 100kHz.

• Publications of The Korean Astronomical Society
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• v.27 no.4
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• pp.187-193
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• 2012

AKARI has 4 imaging bands in the far-infrared (FIR) and 9 imaging bands that cover the near-infrared (NIR) to mid-infrared (MIR) contiguously. The FIR bands probe the thermal emission from sub-micron dust grains, while the MIR bands observe emission from stochastically-heated very small grains and the unidentified infrared (UIR) band emissions from carbonaceous materials that contain aromatic and aliphatic bonds. The multi-band characteristics of the AKARI instruments are quite efficient to study the spectral energy distribution of the interstellar medium, which always shows multi-component nature, as well as its variations in the various environments. AKARI also has spectroscopic capabilities. In particular, one of the onboard instruments, Infrared Camera (IRC), can obtain a continuous spectrum from 2.5 to $13{\mu}m$ with the same slit. This allows us to make a comparative study of the UIR bands in the diffuse emission from the 3.3 to $11.3{\mu}m$ for the first time. The IRC explores high-sensitivity spectroscopy in the NIR, which enables the study of interstellar ices and the UIR band emission at $3.3-3.5{\mu}m$ in various objects. Particularly, the UIR bands in this spectral range contain unique information on the aromatic and aliphatic bonds in the band carriers. This presentation reviews the results of AKARI observations of the interstellar medium with an emphasis on the observations of the NIR spectroscopy.

• Journal of Korea Society of Digital Industry and Information Management
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• v.11 no.3
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• pp.91-98
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• 2015

There is a new evolution in technological advancement taking place called the Internet of Things (IoT), The IoT enables physical world objects in our surrounding to be connected to the Internet. ISM (Industrial Scientific Medical) band that is 2.4GHz band authorized free of charge is being widely used for smart devices. Accordingly studies have been continuously conducted on the possibility of coexistence among nodes using ISM band. In particular, the interference of IEEE 802.11b based Wi-Fi devices using overlapping channel during communication among IEEE 802.15.4 based wireless sensor nodes suitable for low-power, low-speed communication using ISM band. Because serious network performance deterioration of wireless sensor networks. In this paper, we will propose an algorithm that identifies the possibility of using more accurate channels by mixing utilization of interference signal and RSSI (Received Signal Strength Indicator) Min/Max/Activity of Interference signal by wireless sensor nodes. In addition, it will verify our algorithm by using OPNET Network verification simulator.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1655-1660
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• 2014

In this paper, we propose a design of a triple-band microstrip circular patch antenna. The proposed antenna generates the triple frequency resonance at 1.85GHz(LTE), 2.45GHz(ISM) and 5.5GHz(WLAN). Firstly, we design the dual-band antenna. The dual-band antenna consist of the circular patch, slits, and the slot. The circular patch and slot are designed for dual frequency of 2.45GHz and 5.5GHz, respectively. And then the dual-band antenna is combined with additional arm-shaped structure for the triple-band characteristic. The arm-shaped structure is operated as the dipole. It is designed for lowest frequency of 1.85GHz. Each part of the antenna unites to a new structure. In order to design the proposed antenna automatically and optimally, APSO algorithm is adopted. During APSO, the mismatch of the proposed antenna is resolved. The optimal designed antenna has an acceptable return loss(-10dB) at each bands(i.e, 1.85GHz, 2.45GHz and 5.5GHz).

• Journal of Advanced Navigation Technology
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• v.20 no.6
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• pp.556-561
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• 2016

This paper describes implementation of a 13.56 MHz, 5 kW RF high power generator for ISM band applications. This RF generator consists of four LDMOS modules of 1.25kW class-AB push-pull power amplifier with drive amplifier and its outputs are combined by using Wilkinson type transmission-line transformers. Its generator has a high efficiency and output power better than linearity. In order to discharge power transistor heats, we used on water cooled copper plate. Also, these have a composite circuit of combiner and low-pass filter and safety circuit to detector over and reflected power. The RF generator has achieved a efficiency of 79 % at 5.33 kW of saturated power level experimentally.