• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.20 no.10
• /
• pp.1061-1070
• /
• 2009

In this paper, we have designed TDL(True-time Delay Line) for eliminating beam-squint occurring in active phased array antenna with large electrical size operated in wide bandwidth, and have tested its electrical performance. The proposed TDL device is composed of 4-bit microstrip delay line structure and MMIC amplifier for compensation of the delay-line loss. The measured results of gain and phase versus delay state satisfy the electrical requirements, also P1dB output power and noise figure meet the requirement. To verify the performance of fabricated TDL, we have simulated the beam patterns of wide-band active phased array antenna using the measured results and have certified the beam pattern compensation performance. As a result of simulated beam pattern compensation with respect to the 675.8 mm size antenna which is operated in X-band, 800 MHz bandwidth, we have reduced the beam squint error of ${\pm}1^{\circ}$ with ${\pm}0.1^{\circ}$. So this TDL module is able to be applied to active phase array antenna system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.28 no.5
• /
• pp.382-390
• /
• 2017

In this paper, we consider particular exposure scenarios to evaluate human effects for inductive commercial wireless charging device operating at low frequency. The coil used in this study is the A10 model in Qi standard proposed by WPC(Wireless Power Consortium), and input power is 5 W to the operating frequency of 155 kHz. In perfectly aligned condition, the max leakage magnetic field is $257.58{\mu}T$ which is obtained at the side of the device, and it is exceeded about 7.4 times of the ICNIRP 1998 reference level. The SAR is evaluated with homogeneous phantom which has electric constants of wet skin. The max value of the SAR is $134.47{\mu}W/kg$ which is obtained at the side of the device also, and it is much lower than the international guidelines. Especially, it showed higher SAR values in case of misalignment condition, so we will need to consider the misalignment condition importantly when we evaluate human effects for wireless power transfer system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.16 no.11 s.102
• /
• pp.1075-1085
• /
• 2005

The purpose of this paper is to design the architecture for synchronization of MB-OFDM UWB system that is being processed the standardization for Alt-PHY of WPAN(Wireless Personal Area Network) at IEEE802.15.3a and to analyze the implementation loss due to 4 parallel synchronization architecture for design or link margin. First an overview of the MB-OFDM UWB system based on IEEE802.15.3a Alt-PHY standard is described. The effects of non-ideal transmission conditions of the MB-OFDM UWB system including carrier frequency offset and sampling clock offset are analyzed to design a full digital architecture for synchronization. The synchronization architecture using 4-parallel structure is then proposed to consider the VLSI implementation including algorithms for carrier frequency offset and sampling clock offset to minimize the effects of synchronization errors. The overall performance degradation due to the proposed synchronization architecture is simulated to be with maximum 3.08 dB of the ideal receiver in maximum carrier frequency offset and sampling clock offset tolerance fir MB-OFDM UWB system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.6
• /
• pp.706-715
• /
• 2012

Electro-optical sigma-delta modulators are the core module of digital receiver to digitize wideband radio-frequency signals directly at an antenna. Electro-optical sigma-delta modulators use a pulsed laser to oversample an input radio-frequency signals at two Mach-Zehnder Interferometer(MZI) and shape the quantization noise using a fiber-lattice accumulator. Decimation filtering is applied to the quantizer output to construct the input signal with high resolution. The jitter affects greatly on reconstructing the original input signal of modulator. This paper analyzes the performance of first order single bit electro-optical sigma-delta modulator in the time domain and the frequency domain. The performance of modulator is analyzed by using asynchronous spectral averaging of the reconstructed signal's spectrum in the frequency domain. The reference value of time jitter is presented by analyzing the performance of jitter effects. This kind of jitter value can be used as a reference value on the design of modulators.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.21 no.4
• /
• pp.352-361
• /
• 2010

In this paper, a compact 20 W block-up-converter for C-band satellite communication is designed and implemented. The designed block up-converter consists of an intermediate frequency circuit, a mixer and local oscillator, a driver amplifier, a solid-state power amplifier, waveguide circuits, and a power supply module. To reduce the size of the block-up-converter, all circuits are assembled within an housing, so its dimension is just $21{\times}14{\times}11cm^3$. Especially, the waveguide filter and microstirp-to-waveguide transition are easily implemented using an housing. Also, to meet spurious and harmonics specification, various compact microstrip filters including an elliptic filter are integrated. Measurement results show that the developed block up-converter has good electrical performances: the output power of 43.7 dBm, the minimum gain of 65 dB, the gain flatness of ${\pm}1.84$, the IMD3 of -35 dBc, and the harmonic level of -105 dBc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.23 no.7
• /
• pp.805-814
• /
• 2012

Intermittent or periodic signals with undulating amplitudes of mobile devices cause interference noise at audible frequency to the sound system which is installed nearby. In this regard, it is recently issued that the intermittently transmissions of LTE mobile phones cause the interference noises with sound systems, similar to that of GSM mobile phones. For retaining the immunity to noises, a national regulation KN20 suggests a 1 kHz AM 80 % and a CDMA modulation signal as reference signals for immunity test of sound and television broadcast receiver. In this paper, the effects of interference noises of AM and CDMA are compared with those of GSM and LTE, and the improvement of reference signal for national immunity test of sound systems is suggested. It is recommended to delete the CDMA modulation signal from reference signals for immunity test because it hardly cause interference noise with sound systems. On the other hand, it is desirable to select the modulation signal of LTE instead of CDMA as a reference signal for immunity test of sound system and television broadcast receiver because many people use the LTE service and it is analysed that the LTE signal causes considerable interference noises.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.42 no.8
• /
• pp.683-691
• /
• 2014

Significance of SAR(Synthetic Aperture Radar) satellite regadless of weather have grown for Earth observation. According to the cost-effective trend in satellite development, SAR antenna is actively studied. It's a competitive candidate to use deployable SAR antenna out of CFRP. In this study, variables for an antenna configuration model was researched and evaluated. The design of the antenna was structurally analyzed by FEM(Finite Element Model). Tool-kit was developed for modifying the SAR antenna model easily in accordance with system requirement change. In the tool-kit, antenna configuration design and error analysis of the antenna surface could be achieved. And compatibility of tool-kit results to CST, a RF analysis program, was confirmed.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2004.04a
• /
• pp.11-15
• /
• 2004

This paper deals with EMC filter for a personal computer( PC). A PC contains many sources of noise inside and out, with many connected cables. High noise levels are also emitted from the PC became of high-speed signals. So radiated noise from the computer body may sometimes cause problems. Therefore, we design and fabricate an electromagnetic compatibility (EMC) filter for PC, which is composed of feed-through capacitors and ferrite beads with high permeability. Through extensive test, the proposed EMC filter is shown to have excellent differential-mode and common-mode noises filtering characteristics above 30 dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8 GHz

• Journal of Navigation and Port Research
• /
• v.28 no.8
• /
• pp.715-719
• /
• 2004

This paper deals with EMC filter for a personal computer(PC). A PC contains many sources of noise inside and out, with many connected cables. High noise levels are also emitted from the PC because of high-speed signals. So radiated noise from the computer body may sometimes cause problems. Therefore, we design and fabricate an electromagnetic compatibility (EMC) filter for PC, which is composed of feed-through capacitors and ferrite beads with high permeability. Through extensive test, the proposed EMC filter is shown to have excellent differential-mode and common-mode noises filtering characteristics above 30 dB in the frequency band from 10 MHz to 1.5 GHz. The immunity characteristics are improved more than 10 to 30 dB over the frequency band from DC to 1.8 GHz.

• Journal of IKEEE
• /
• v.21 no.3
• /
• pp.248-251
• /
• 2017

In this paper, The proposed board is developed by EMI compliant Dash Camera with $360^{\circ}$ omni angle. The proposed board is designed by designing DM and CM input noise reduction circuit and applying active EMI filter coupling circuit. The DM and CM input noise reduction circuit design uses a differential op amp circuit to obtain the DM noise coupled to the input signal via the parasitic capacitance(CP). In order to simplify the circuit by applying the active EMI filter coupling circuit, a noise separator is installed to compensate the noise of the EMI source to compensate the CM and DM active filter simultaneously. In order to evaluate the performance of the board for the proposed EMI response, an authorized accreditation body has confirmed that the electromagnetic certification standard for each frequency band is satisfied.