• Journal of Power Electronics
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• v.17 no.3
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• pp.798-810
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• 2017

This paper presents a combined system of a small-capacity inverter and multigroup delta-connected thyristor switched capacitors (TSCs). The system is referred to as a hybrid static compensator (HSC) and has the functions of dynamic reactive power compensation and harmonic suppression. In the proposed topology, the load reactive power is mainly compensated by the TSCs. Meanwhile the inverter is meant to cooperate with TSCs to achieve continuous reactive power compensation, and to filter the harmonics generated by nonlinear loads and the TSCs. First, the structure and mathematical model of the HSC are discussed Then the control method of the HSC is presented. An improved reduced order generalized integrator (ROGI)-based selective current control method is adopted in the inverter to achieve high-performance reactive and harmonic current compensation. Meanwhile, a switch control strategy is proposed to implement precise and fast switching of the TSCs and to avoid changing the time delay needed by the conventional switch strategy. Experiments are implemented on a 20 KVA HSC prototype and the obtained results verify the validity of the proposed HSC system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.159-164
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• 2004

In this paper, we have proposed the folded feed structure for the spurious harmonic suppression and we have designed the SIR CPW bandpass filter using this feed structure. The characteristic of the proposed feed structure was similar to that of the lowpass filter has wide stopband region and this can be used usefully to the spurious harmonic suppression of the bandpass filter. From the simulation and the measurement result, SIR CPW bandpass filter with folded feed structure has good harmonic suppression characteristics up to 5.8 f$\sub$0/ with -20 dB suppression level.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2005.11a
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• pp.101-106
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• 2005

This paper presents a new microwave oscillator incorporating a corrugated coplanar waveguide (CCPW) electromagnetic bandgap (EBG) structure as its terminating resonance component. The use of a compact CCPW EBG structure was effective in reducing the phase noise and improving the harmonic characteristics of the microwave oscillator circuit without additional backside processing and drastic size increment. The fully planar CCPW oscillator oscillating at the frequency of 5.41 GHz showed a phase noise characteristic of -90.7 dBc/Hz at 100kHz offset and a second harmonic suppression of 42.67 dB.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.197-201
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• 2006

Folded lines are applied to design a compact microstrip ring hybrid. Using the proposed structure we achieve both significant size reduction and good harmonic suppression with the same results of conventional ring hybrid at 2.41GHz. Including the third harmonic frequency, up to 11GHz band harmonics are suppressed to -20dB. The size of the proposed ring-hybrid is reduced to one forth of the conventional ring hybrid. The measured frequency responses agree well with simulated ones.

• Journal of the Korea Institute of Military Science and Technology
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• v.11 no.3
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• pp.146-153
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• 2008

High-power communication jammer has to include the switched filter bank to eliminate the harmonic signals generated by amplifier. Generally, the switched filter bank consists of in-out switches and several filters. This paper describes the design of high-power switched filter bank, particularly the high-power filter bank operating over 20$\sim$110MHz frequency range. The filters designed have insertion loss less than 0.3dB, VSWR less than 1.25:1, and harmonic suppression more than 35dB. Also, the switched filter bank can endure upto 2kW high-power signal with very low harmonic level within $30{\mu}s$ switching speed.

• Transactions on Electrical and Electronic Materials
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• v.17 no.4
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• pp.217-221
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• 2016

In this work, open and short stubs that were fabricated on the silicon substrate and for which the periodically arrayed grounded-strip structure (PAGS) was employed were studied along with their basic RF characteristics for an applicability regarding the RF-matching components. The PAGS-employing open and short stubs showed losses that are much lower than that of the conventional stub on the silicon substrate. Concretely, the Q values of the open and short stubs are 9 and 10.2, respectively, while the Q value of the conventional open stub is 2.5. With the use of the PAGS-employing open and short stubs, a highly miniaturized harmonic-rejection filter was also fabricated on the silicon substrate. The filter exhibited a comparatively sound harmonic-suppression characteristic at n × 13 GHz, and its size is 0.1 mm², which is only 7% of the size of the conventional filter on the silicon substrate.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.513-520
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• 2003

In this paper, a novel design concept of frequency doubler using feedforward technique and DGS microstrip line is proposed. The feedforward loop plays a role of fundamental frequency suppression and DGS microstrip line suppresses over the 3rd order harmonic components. By using this new concept, the high suppression for the undesired signals could be achieved easily. The proposed technique is experimentally demonstrated in 1.87 GHz-to-3.74 GHz frequency doubler. The output power of -3 dBm at the frequency of 3.74 GHz(2f$\_$0/) is measured with 42.9 dB suppression of the fundamental frequency signal(f$\_$0/), 20.2 dB suppression of the 3rd harmonic signal(3f$\_$0/) and B9.7 dB suppression of the 4th harmonic signal(4f$\_$0/). The conversion loss of -2.34 dB ∼ -5.8 dB at the bandwidth of 100 MHz, the phase noise of -97.51 dB/Hz(＠10 kHz) were measured.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.5
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• pp.697-706
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• 2000

In this paper, new bandpass filters that are composed of microstrip ring resonators with the center frequency of 5.775 GHz and the bandwidth of 100 MHz are presented. For the suppression of the unnecessary harmonics, lowpass filters are inserted into the feedlines and ring resonator itself, respectively These bandpass filters show good microwave characteristics with the harmonic suppression ratio of about 39 dB and 35 dB, respectively. Also, the varactor-tuned microstip ring bandpass filter with harmonic suppression is suggested and the tuning bandwidth of more than 450 MHz is obtained.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.1
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• pp.19-25
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• 2015

In this paper, a design method for a CPW-fed slot antenna for harmonic suppression is studied. The structure of the proposed slot antenna is a rectangular slot antenna appended with stepped impedance resonators (SIRs) at both ends of the slot symmetrically. Optimal design parameters are obtained by analyzing the effects of the length and width of the SIRs on the input reflection coefficient. The optimized harmonic-suppressed slot antenna operating at 2.45 GHz WLAN band is fabricated on an FR4 substrate with a dimension of 42 mm by 30 mm. The slot length of the proposed harmonic-suppressed slot antenna is reduced to 33.3% compared to that of a conventional rectangular slot antenna owing to the appended SIRs. Experiment results show that the antenna has a desired impedance characteristic with a frequency band of 2.39-2.49 GHz for a VSWR < 2, and a measured gain of 2.5 dBi at 2.45 GHz.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.2A
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• pp.122-128
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• 2005

In this paper, a low noise parallel feedback oscillator for harmonic suppression and a frequency doubler are designed and implemented. As the fundamental signal of the oscillator for frequency doubling is extracted between the dielectric resonator (DR) filter and the gate device of the active device, the undesired harmonics at the output of the oscillator is remarkably suppressed. The fundamental signal of the oscillator for frequency doubling directly feeds to the frequency doubler without an additional band pass filter for harmonic suppression. The second harmonic suppression of -47.7 dBc at the oscillator output is achieved, while the fundamental suppression of -37.5 dBc at the doubler output is obtained. The phase noise characteristics are -80.3 dBc/Hz and -93.5 dBc/Hz at the offset frequency of 10 KHz and 100 KHz from the carrier, respectively.