• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.854-861
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• 2007

In this paper, a compact L-shaped shorted pin patch to be used at local oscillator port in radar detector is proposed. Shorted pin patch operates as short-open cavity while conventional patch operates as open-open cavity. Shorted pins are L-shaped to obtain quarter wave length and three-quarter wave length resonance for the fundamental(X-band) and $2^{nd}(3^{rd})$(K- and Ka-band) mode resonance frequency, respectively. Thus, the proposed patch can be compact. It is also possible to operate at triple band(X-, K-, Ka-band) with small return loss in radar detector, It is expected that shorted pin patch could improve radar detector sensitivity.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.441-444
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• 2018

In this paper, a microstrip antenna for LTE / WiMAX is designed for UWB communication. The proposed antenna is designed for FR-4 (er = 4.3), 29[mm] x 45[mm], and can be used in the LTE frequency band of 1.82[GHz] and the WiMAX frequency band of 3.5[GHz]. Studio 2014 was used. The simulation results show 1.785[dB] at 1.82[GHz] and 1.720[dB] at 3.5[GHz]. S-parameters were also found to be less than -10dB (WSWR2: 1) in the desired frequency band. In order to achieve broadband, miniaturization, low cost and low loss, Width, length, width of transmission line, etc. were calculated. Therefore, it is considered that the applicable antenna can be applied satisfying the desired condition.

• Composites Research
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• v.35 no.3
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• pp.201-215
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• 2022

This paper presents the development of thin and lightweight ultra-high temperature radar-absorbing ceramic composites composed of an aluminosilicate ceramic matrix-based geopolymer reinforced ceramic fiber and sendust magnetic nanoparticles in X-band frequency range (8.2~12.4 GHz). The dielectric properties with regard to complex permittivity of ceramic/sendust-aluminosilicate composites were proportional to the size of sendust magnetic nanoparticle with high magnetic characteristic properties as flake shape and its concentrations in the target frequency range. The characteristic microstructures, element composition, phase identification, and thermal stability were examined by SEM, EDS, VSM and TGA, respectively. The fabricated total thicknesses of the proposed single slab ultra-high temperature radar absorber correspond to 1.585 mm, respectively, exhibiting their excellent EM absorption performance. The behavior of ultra-high temperature EM wave absorption properties was verified to the developed free-space measurement system linked with high temperature furnace for X-band from 25℃ to 1,000℃.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2004.07a
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• pp.328-328
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• 2004

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.9
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• pp.800-807
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• 2016

In this paper, we study the characteristics of dual band microstip antenna with modified inset feeder and a single slot. The modified inset feeder consists of the vertical inset feeder placed in x direction and the horizontal one in y direction for shortening the total length of inset feeder. The optimun feeding position for good impedance matching at two resonant frequencies can be easily found by adjusting the horizontal inset distance. And Various frequency ratios can be simply obtained by the parameters of slot. The measurements for fabricated antenna prototypes are carried out for validation. The measured results show a tunable frequency ratio from 1.25 to 1.88 with the variation of slot parameters. It is worthwhile to point out that the radiation patterns are similar at both bands. and below -20.0 dB of cross polarization level at the E plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.6
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• pp.533-539
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• 2015

In this paper, we designed a reconfigurable mixer for microwave broadband receiver. The proposed mixer using a anti-parallel diode is operated as a fundamental mixer or sub-harmonic mixer with respect to a control voltage. A fundamental mixer with a control voltage show a conversion loss of -10 dB, 1 dB compression point of 2.0 dBm at X-band/ Ku-band. On the other hand, it is performed as a sub-harmonic mixer with a conversion loss of -17 dB, 1 dB compression point of 2.0 dBm at Ka-band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.2
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• pp.89-95
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• 2003

This paper proposes downlink blocking model and approximation equation using lower bound approximation in order to determine the proper guard band between cdma2000 1X and WCDMA in handover areas. The frequency sharing conditions obtained by the model and approximation equation on blocking probability proposed in the paper, are co-site of base station and guard band higher than 1 MHz. Also, the proposed equation is in the form of Q-function. It is an analytical solution overcoming the drawback of recalculation, belonged to Monte-Carlo technique.

• Composites Research
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• v.19 no.1
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• pp.36-42
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• 2006

MWNT(multi-walled carbon nanotube)-filled plain-weave glass/epoxy composites were fabricated and electromagnetic characteristics of the composites were investigated. The observation of the microstructures of the composites revealed that MWNTs are mostly distributed in matrix rich region and the interface between glass fiber yarns in warp and fill direction. The permittivity of the composites, measured in X-band (8.2-12.4 GHz) frequency range, increased with weight fraction of MWNTs and remained almost constant with frequency. The measured permittivity was used to investigate the reflection loss of radar absorbing structures (RAS) composed of MWNT-filled composites according to thickness and a RAS were constructed with 10 dB absorbing bandwidth 4.2 GHz and 3.3 mm in thickness.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.269-272
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• 2003

A low phase noise frequency synthesizer at X-Band which employs the subharmonic injection locking was designed and tested. The frequency synthesizer consists of two oscillators - master and slave : A 1.75GHz master oscillator made of PLL synthesizer produces 6th harmonic at 10.5GHz, which excites the following 10.5GHz slave oscillator. The realized frequency synthesizer has a 4.5dBm of output power, and a phase noise of -108dBc/Hz at the 100kHz offset frequency.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.943-948
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• 2018

In this paper, SSPA Module for X-band radar was designed and fabricated by using GaN MMIC. For the purpose of configuring the high power SSPA module, the drive steamers are composed of 2-layers of GaN MMIC with considering Gain Loss. In addition, the power divider and power combiner used a 4way approach by designing a 4-stage power amplifier. The power divider has a loss of -3.0dB or more, and the I/O has a loss of -0.2dB in the power combiner and the phase difference between the ports are good at $2^{\circ}$ on average. The fabricated SSPA module got the measurement results that satisfy a Gain 48dB, P(sat)=88.3W(49.46 dBm), PAE=30.3% or more efficiency in condition of frequency range 9~10GHz. The fabricated X-Band SSPA module can be applied in RF performance improvement for SSPA module whit improvement of power divider/combiner.