• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.51-56
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• 2020

Measurement accuracy and required time is important to make ATE(Automatic test equipment) system in Ka band, and SCPI commands of power meter which is a representative RF test equipment are studied in this paper. Comparison data between FETCH and MEASURE which are SCPI commands are measured in 30 G ~ 31 GHz and -70 ~ +20 dBm using two power sensor. The data show that FETCH which is the fastest SCPI is able to get reliable data in linear interval above noise level. MEASURE which is the best accurate command takes longer time than FETCH, and the longest time is 13.2 seconds. These results offer that measurement accuracy and required time of the two SCPI for power meter and would be used as a guideline for efficient ATE system in Ka band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1060-1070
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• 2003

The frequency selective surface for use in Ka/Ku band parabolic antenna of domestic satellite communications is proposed. The frequency selective surface structure consists of the infinite periodic arrays of the triple square loop slot element with narrow width on the honeycomb structure of multi-layered dielectric. The frequency selective surface is fabricated and measured. The good agreement is obtained between theory and experiment. It is demonstrated that the frequency selective surface passes 14/12 GHz band wave while reflecting 30/20 GHz band wave as required.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.1
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• pp.231-238
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• 2019

In this paper, we have studied how to improve the amplifiers efficiency by minimizing the combining loss when several unit power amplifiers are combined to obtain high output power. Specifically, we have developed Ka-band Spatial Combining Amplifier. The fabricated Spatial Combining Amplifier is a Ka-band 20W class SSPA, which uses a 5W class unit amplifier module 8EA designed using a GaN bare die. We also combined The unit amplifier module using 8-way spatial divider and combiner with a hybrid radial structure. The output combining loss of the fabricated spatial coupler is about 0.334dB, which is about 92.6% efficiency. In this paper, we developed a Spatial Combining Amplifier with a maximum saturation output of 10W and a power addition efficiency of over 15%. As a result, we achieved the maximum saturation output of 30W and the power addition efficiency of 19%.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.323-326
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• 1998

A LNA(Low Nosise Amplifer) module for the Ka-band satellite transponder has been developed, which is composed of developed two MMIC chips and 50$\Omega$ line. This LNA exhibited noise figure less than 3.12dB, linear gain higher than 32dB from 30.085GHz to 30.885GHz frequency range. Temperature test from $20^{\circ}to$ $60^{\circ}C$ of the LNA Module showed very small noise figure and linear gain variation of 0.2 dB and 0.4dB.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.2
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• pp.227-231
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• 2004

A MMIC (Monolithic Microwave Integrated Circuit) mixer chip using the schottky diode of InGaAs/CaAs p-HEMT process has been developed for receiver down converter of Ka-band. A different approach of MMIC mixer structure is applied for reducing the chip size by the exchange of ports between IF and LO. This MMIC covers with RF (30.6∼31.0㎓)and IF (20.8∼21.2㎓). According to the on-wafer measurement, the MMIC mixer with miniature size of 3.0mm1.5mm demonstrates conversion loss below 7.8㏈, LO-to-RF isolation above 27㏈, LO-to-IF isolation above 19㏈ and RF-to-IF isolation above 39㏈, respectively.

• Journal of Satellite, Information and Communications
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• v.8 no.3
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• pp.47-51
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• 2013

In this paper, we present design and test results of a Ka-band dual-band ortho-mode transducer (OMT) for use in a feed assembly for the very small aperture terminals (VSATs). The designed ortho-mode transducer have wideband characteristics to separate the signals that have two orthogonal linear polarizations operating at 20GHz of receive frequency band and at 30GHz of transmit frequency band. In addition, in order to reduce the volume of the feed assebly, a Boifot based ortho-mode transducer has been designed with a dual-band. Experimental results for the design verification, the return loss in the receive band and in the transmit band for the horizontal polarization showed over 20dB and 21dB, respectively, and for the vertical polarization showed over 20dB and 24dB, respectively. The port isolation for the horizontal polarization and the vertical polarization showed over 43dB and 52dB, respectively, in the receive band and in the vertical band.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.1
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• pp.68-74
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• 2003

This paper describes the design and the test results of the receiver-downconverter module for a Ka-band Satellite Payload. The developed module is not only a downconverter that convert the signal of 30.6 GHz∼31.0 GHz to the signal of 20.8 GHz∼21.2 GHz but also is a receiver that has the function of low noise amplification in the front stage. It has been fabricated and tested by the qualified satellite component manufacturing process and it shows the best performance of the receiver-downconverter modules operating at Ka-band frequency up to date. The module has the performance of 1.9 dB-NF, 55 dB-Gain, and 58 dBc-C/I3 fur the two tone signals of -59 dBm input power respectively at ambient temperature. It is a small and light module with the size of 93 mm${\times}$84 mm${\times}$26 mm and the weight of 240 g.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.11B
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• pp.1696-1703
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• 2010

Increased demand for military satellite communications system and due to the depletion of resources of existing satellite communications frequencies, Ka-band and EHF-band satellite communication systems is growing demand for development. As a result, the study of rain attenuation mitigation for Ka/EHF-band frequencies has been achieved. The method to compensate rain attenuation on Ka-band(20/30) using the signal power measurement function in Digital Transponder of Next Military Satellite has been proposed in this paper. This method is more effective than generally used method by Beacon and UPC(uplink power control) in giving the precise rain attenuation measurement and correction.

• Journal of Life Science
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• v.20 no.4
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• pp.481-486
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• 2010

The rates of synonymous and nonsynonymous nucleotide substitutions were studied for sequences of nuclear and chloroplast genes in Sorbus aucuparia. Results suggested that DNA evolution in this species had taken place, on average, at a slower rate in the chloroplast genes than in the nuclear genes: a rate variation pattern similar to those observed in eudicot plants. Within the nucleus, the synonymous substitution rates (Ks) (2.45-2.60) were two-fold higher than nonsynonymous substitution rates (Ka) (1.15-1.30). More notably, the values of Ks (1.20-1.26) were about six-fold higher than those of Ka (0.26-0.42) within the chloroplast genome. Ka/Ks ratios for nuclear and chloroplast genes of S. aucuparia had mean values of 0.178 and 0.056, respectively. A Ka/Ks ratio < 1 indicated negative (purifying) selection. The chloroplast genes had a lower effective number of codons (ENC) values (22.4-32.2) than those of nuclear genes (35.8-38.7). The analysis of the G+C content indicated that the chloroplast genes in this investigation had a higher preference for synonymous codons ending with A and T (G+C content range, 28.4-29.1%) where there was a slight bias toward codons ending with G+C (63.2-64.2%) in the nuclear genome.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.7 s.98
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• pp.732-739
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• 2005

In this paper, the design and implementation of the Ka-band(20/30 GHz) waveguide diplexer with an E-plane T-junction are described. The waveguide diplexer consists of a transmit filter and a receive filter combined to the antenna port via an E-plane T-junction. The reason why the E-plane T-junction structure was selected is to reduce PIM(Passive Intermodulation) level as the split-plane is located in the low electrical current zone. The optimization was performed using the equivalent circuit so that the computation time might reduce. The structure of the diplexer was designed to handle high power and the multipaction analysis was performed. The multipaction margin was greater than 12 dB and satisfied with ESA/ESTEC recommendation. The manufactured diplexer shows minimum return loss of 22 dB, maximum insertion loss of 0.20 dB and maximum isolation of -40 dB for both transmitted receive bands. Those mean the analysis results of the waveguide diplexer were well agreed with the electrical performance test.