• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.7
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• pp.67-71
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• 2008

We report the waveguide to microstrip transition using probe structure for Ka-band transceiver. The waveguide to microstrip transition is composed of probe, inductive line, ${\lambda}/4$ impedance transformer, and $50{\Omega}$ microstrip line. For design of the transition, we optimized the characteristic impedances and the lengths of the component parts. The fabricated transition exhibits an insertion loss of 1.3 dB and the input/output return losses of below 14 dB between 30 and 40 GHz. The insertion loss of each transition is about $0.5{\sim}0.6dB$, considering the losses in the microstrip line and input/output waveguides.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.296-303
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• 2008

Co-existence of various wireless systems may cause frequency interference problem. For this reason, frequency sharing studies play a very important role in order to use limited spectrum resources efficiently. Especially, because a satellite system covers a global area in nature, the frequency sharing between the satellite system and terrestrial systems is essential. For satellite systems using Ka bands, we can increase spectrum efficiency by considering off-axis angles of earth station antenna. In this paper, we demonstrate the analysis result of separation distance between the satellite earth station and a terrestrial repeater, and the presented results can be used to design and implement Ka band wireless systems.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.5 s.120
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• pp.511-521
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• 2007

In this paper, we designed and fabricated a Ka-band synthesizer module. In addition, the systematic layout procedure and the test procedure were presented for the construction of compact synthesizer. To implement the Ka-band synthesizer, X-band VCO is employed as VCO and its frequency was multiplied by 3 with frequency tripler. The fabricated frequency synthesizer shows a frequency tuning range of 500 MHz, output power of about 14 dBm, and a phase noise of -96.17 dBc/Hz at the 100 kHz offset frequency.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.4
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• pp.105-111
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• 2019

In this paper, a performance analysis of waveguide broad-wall slot array antenna for millimeter-wave seeker in Ka-band was performed as using near-field measurement. The measurement of slot array antenna was conducted in both far-field and near-field. And the validation of near-field test in millimeter band was confirmed. It was confirmed that the beam pattern characteristics including beam width and side lobe level of the slot array antenna that performed the verification were the same. Differenced in the side lobe level of azimuth and elevation beam pattern were verified to be less than 1dB. Additionally, the new antenna aperture distribution was extracted as using back-projection method modifying the near-field data and then introduced the method conducting performance analysis of array antenna.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.63-70
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• 2020

In this paper, the transmit-receive module for military seekers has been designed and fabricated in 35 GHz. To increase the performance of substrates and high integration of circuits in millimeter-wave band, a 4-layer LCP(Liquid Crystal Polymer) substrate was developed. This substrate was implemented with three FCCL substrates and two adhesive layers, and a process using the difference in melting point between the substrates was used for lamination. Using a strip line and a microstrip line was confirmed by the transmission loss along the length of the substrate, and the performance of LCP substrates was validated with a power divider in 35 GHz. After confirming the performance of individual blocks such as power amplifier and low noise amplifier, a single channel Ka-band transmission/reception module was developed using a 4-layer liquid crystal polymer substrate. The transmit power of this module has above 1.1W in pulse duty 10% and has an output power of 1.1W and it has receive noise figure less than 8.5 dB and receive gain more than 17.6 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.2
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• pp.220-228
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• 2012

In this paper, we explained the design technique about Ka-band active limiter for protecting the receiver of a millimeter wave seeker. To implement low flat leakage power, we proposed the control circuit of active limiter to control limiter voltage with PRF(Pulse Repetition Frequency) signal and input power. This active limiter consisted of the conventional 2 stage passive limiter, a feedback circuit with a directional coupler, detector, non-inverting amplifier and over-current protection resistance. As the test result of the fabricated Ka-band limiter, it had 1 GHz bandwidth, 3.5 dB insertion loss at the small input power and -7.5 dBm flat leakage at the 4 W RF input power, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.12
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• pp.8643-8648
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• 2015

In this paper presents the design and demonstrate 8 W 3-stage HPA(High Power Amplifier) MMIC(Monolithic Microwave Integrated Circuits) for Ka-band down link satellite communications payload system at 19.5 GHz ~ 22 GHz frequency band. The HPA MMIC consist of 3-stage GaN HEMT(Hight Electron Mobility Transistors). The gate periphery of $1^{st}$ stage, $2^{nd}$ stage and output stage is determined $8{\times}50{\times}2$ um, $8{\times}50{\times}4$ um and $8{\times}50{\times}8$ um, respectively. The fabricated HPA MMIC shows size $3,400{\times}3,200um^2$, small signal gain over 29.6 dB, input matching -8.2 dB, output matching -9.7 dB, output power 39.1 dBm and PAE 25.3 % by using 0.15 um GaN technology at 20 V supply voltage in 19.5~22 GHz frequency band. Therefore, this HPA MMIC is believed to be adaptable Ka-band satellite communication payloads down link system.

• Electronics and Telecommunications Trends
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• v.22 no.3 s.105
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• pp.166-173
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• 2007

WRC-97에서 HAPS 개념이 도입된 후, HAPS 이용 주파수 대역으로 IMT-2000 대역과 Ka 및 V 대역이 지정되었다. IMT-2000 대역에 대한 공유 및 규정 연구는 WRC-03에서 종료되었으나, Ka 및 V 대역에서 타 무선업무와 HAPS를 이용한 고정업무 간의 기술적, 운용적 그리고 규정에 관한 연구를 지속하고 WRC-07에서 연구결과를 검토하기로 하였다. 본 고에서는 WRC-03 회의에서 결의한 IMT-2000 서비스를 제공하는 HAPS 시스템의 이용에 관한 규정 현황을 알아보고, 현재 ITU-R에서 논의중인 Ka및 V 대역에서 HAPS 시스템 활용을 위한 규정 연구 현황을 살펴보고자 한다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.4
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• pp.320-323
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• 2018

Herein, an ultrawideband spinning direction finding (DF) antenna was designed and fabricated for airborne applications. The proposed antenna is designed by dividing the low-band (UHF - L band) and high-band (S - Ka band) antennas to cover the ultrawideband frequency range (UHF - Ka band). For the high-band antenna, an LPDA antenna fed offset-parabolic-reflector antenna is applied. In the low-band antenna, two LPDA antenna elements are arrayed in front of the reflector of the high-band antenna without increasing to the full antenna size. The low- and high-band gains of the fabricated antenna were measured as 8.76 dBi and 24.55 dBi on average, respectively. The antenna was fabricated with the dimensions of 437 mm in diameter and 358 mm in height. Consequently, we confirmed that the designed antenna is appropriate for the spinning DF antenna in terms of the affordable size for installing on an airplane, as well as the high gain and narrow beamwidth.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.7
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• pp.1797-1806
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• 1998

Future satellite communication systems will be developed at Ka-band (20/30 GHz) owing to the relatively wide frequency allocation and current freedom from terrestrial interference for multimedia services. A serious disadvantage of the Ka-band, however, is the very high atmospheric attenuation in rainy weather. Synchronous CDMA drastically redces the effect of self-noise with several interesting features of CDMA for mobile communications such as fixible freuqncy rese, the capability of performin soft-handover and a lower sensitivity to interference. This paper evaluates the performance of a synchronous CDMA reture link for a Ka-band geostationary satellite communication system. For a fixed satellite channel whose characteristics depend on weather conditions, the signal envelope and phase for this channel is modelled as Gaussian. The bit error and outage probability, and the detection loss due to imperfect chip timing synchronization is analytically evaluated and the system capacity degaradation due to the weather condition is estimated. The two cases consist of the general case in which all users are affected by rain condition, and the worst case in which the reference user is only affected by rain attenuation. the results for two cases of rain condition clearly show that synchronous CDMA eases the power control requirements and has less sensitivity to imperfect power control.