• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.5
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• pp.530-536
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• 2021

This paper presents the performance measurement results of a hybrid sheet with both shielding and heat dissipation functions developed by laminating copper mesh sheets and natural graphite sheets, which are used widely as electromagnetic shielding and heat-dissipating materials in electronic devices, without a pressure-sensitive adhesive (PSA). The results were compared by measuring the vertical and horizontal thermal conductivity with two other products to confirm the heat dissipation performance. A radiation emission test confirmed the electromagnetic shielding performance using a 3m electromagnetic anechoic chamber according to the CISPR 11 standard. In the case of vertical thermal conductivity, the proposed hybrid sheet was approximately 8.63 times higher than that of an aluminum sheet with heat dissipation coating and 18.7 times higher than that of a copper sheet laminated with artificial graphite with PSA. The proposed hybrid sheet was approximately 0.64 times that of the sheet, and approximately 1.76 times that of the heat-dissipated aluminum sheet in case of horizontal thermal conductivity. Measurements after applying each sheet in the same heat source revealed the proposed hybrid sheet to have the best heat dissipation performance. The radiation emission test showed that significantly radiation noise had been removed.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.6 s.109
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• pp.519-528
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• 2006

This thesis is regarding of fabricating wibro PAM. First of all, we need to set specification based on link budget for wibro communication circumstance in order to develop PAM, then we decided specification concerning of wibro PAM by considering TTAS_Ko_06_0082R1 which is standarded in Korea, and IEEE Std. 802. 16d/e which is international standard. We selected the Doherty structure to increase efficiency, and pre-distorter structure to increase linearity. The fabricated PAM has not only a result of $26.5dB{\pm}1.0dB$ gain characteristics and maximum of -14 dB return loss characteristics in full frequency bands and full output ranges, but also a result of 37 dBc at 4 tone IMD characteristics which is improved result of 843 and a result of 31 dBc spurious characteristics which is improved result of 5 dB at 4.77 MHz offset point in status of having 27 % efficiency in the 26 dBm high power amplifier output signal. We confirmed the suggested structure is better than others by comparing with normal structure, balanced structure and Doherty structure without predistorter.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.4
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• pp.473-478
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• 2011

The extent of a rectangular conducting plane for measuring electromagnetic interference is discussed. Mutual coupling between the transmit and receive antennas is negligible, the effects of the ground plane on the normalized site attenuation(NSA) are considered by applying GTD(Geometric theory of diffraction). The calculation was done for the case that measuring distance(d) was 3 m for both horizontal and vertical polarizations. As the result, the size of the rectangular ground plane almost never affects upon NSA for horizontal polarization, but for vertical case, when both width and length of the rectangular plane are several times as long as distance, the effects of the edges are reduced under 1 dB.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.633-636
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• 2017

This thesis is about the evaluation method of field uniformity for radiated immunity test of vehicle component. Radiated immunity test is to find out whether a EUT has enough immunity or hold normal operation during applied electromagnetic interference. Field Uniformity(FU) measurement is essential for generate uniform field on DUT and Harness. But Standard of Radiated Immunity(RI) test for vehicle component based on ISO 11452-2 has not been specified a Field Uniformity(FU). So compared and analyzed with other standard which is defined by a specified a Field Uniformity. As a result, deviation occurs in the difference test condition and test method. In this thesis, proposal new measurement method of field uniformity that is considered test conditions of ISO 11452-2 and check the validity through actual test.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1172-1175
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• 2011

In this paper, a design method of multi-tone signals for the measurement of adjacent-channel power-ratios on power amplifiers is suggested. Because most tests for power amplifiers in production are performed with single-tone signals, its testing accuracy is not guaranteed as the signal complexity increases. Therefore, the application of multi-tone signals to the testing is suggested by optimized complex coefficients of each tones for the best statistical similarity to the original modulated signal. From the verification, a 802.11a signal was replaced with a multi-tone signal of N=10, with the complex coefficients generated by the suggested method. The resulting measurements on the ACLR of 2.4 GHz power amplifier showed successful accuracy of less than 1 dB discrepancy.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.401-406
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• 2018

In this paper, we present E-band bond-wire modeling and a matching network to compensate for the effect of the bond-wire. The impedance of the bond-wires is extracted using three-dimensional electromagnetic simulation. The matching network was designed using a simple structure. The implemented matching network was verified with a commercial 71~81 GHz LNA IC and an interconnection based on the WR-12 waveguide. The matching network increases the transmission coefficient of the system by up to 4.5 dB, power gain by up to 3.12 dB, $P_{1dB}$ by up to 2.2 dB, and improves the gain flatness by ${\pm}1.07dB$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.8
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• pp.791-797
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• 2013

This paper proposes a new way to verify the performance of an absorber lined shielded enclosure(ALSE) in accordance with CISPR25, EMC standards dedicated to testing automotive components. CISPR16 requires the use of NSA and VSWR methods to test the performance of a chamber. As for CISPR25, however, there hasn't been standardized ways to verify the performance of ALSE. This paper purports to present an improved method for the verification based on a long-wire antenna method under discussion at CISPR25 JFT. Existing discussions on a long-wire antenna method proposes that an antenna should reach 500 millimeters in length, while this paper adopts the antenna length of 1,700 millimeters. This paper also assesses the effects of matching conditions and studies problems related to methods which have been already proposed and key parameters in order to improve verification methods.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.5
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• pp.510-518
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• 2010

In this paper, the designed and implemented results of CFL linearization chip which can be used in mobile radio and TRS terminal of UHF band(380~910 MHz), using $0.6\;{\mu}m$ BiCMOS process based on Si, are shown. As gain control circuits for modifying transmit power are inserted not only in feedback path but also in forward path, the stability of CFL is maintained. And, DC-offset correction function of S/H structure, which is suitable for walkie-talkie PTT operation and is easily implemented, is realized. The performance test results of transmitter show that the regulation of FCC emission mask at PEP 3 W(34.8 dBm) is satisfied when the CQPSK modulated signal is fed and more than 30 dBc improvement of 3rd order IMD is achieved when two-tone signal is inputted.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.5
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• pp.558-565
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• 2013

In this paper, modeling and simulation for performance analysis of high resolution SAR system has been carried out in the time, frequency and numeric domain using ADS Ptolemy simulation tool of Agilent corporation. SAR system consists of antenna, controller and transceiver. Error parameters affecting SAR system performances have been defined, modeled and simulated such as phase noise of frequency synthesizer, amplitude and phase characteristic of TWTA, sampling frequency of waveform generator and I/Q imbalance. Finally, the development requirements of SAR system based on the impulse response function have been derived.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.5
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• pp.463-470
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• 2015

In this paper, a new dual-band bandpass filter(BPF) that has resonators and feed lines with Stepped-Impedance Resonator(SIR) structures is proposed. Feed lines with SIR structure provide maximum magnetic field points which occur at the same locations of the input and output feed lines, so the insertion loss of BPF was reduced. Applying the SIR structure to the BPF for the first passband improves rejection characteristics between the first passband and the second passband. It reduces the coupling between the BPF for the first passband and the BPF for the second passband, so it makes the dual-band BPF more compact. The proposed design method provides independent changes of both the center frequency and the bandwidth for each resonator, and also improves filtering characteristics. The validity of the proposed design method is confirmed by comparisons between the designed parameters and the measured results satisfying WLAN specifications.