• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.3
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• pp.515-522
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• 1994

The radiation characteristics of the conical corrugated feed horn are analyzed by the Gaussian beam mode theory. the electric field over the aperture can be expanded in terms of a set of Gaussian-Laguerre modes. It is proved that these modes are the solutions of the wave epuations for the paraxial approximation. A method, using the sum of the mode expansion coefficients instead of calculation only the fundamental mode, is presented in order to reduce the radiation pattern error. For illustrative examples, the radiation patterns of the corrugated horn antenna operting over C, Ku, and mm-wave band are calculated. Our results agree well with the results obtained by the vector potential method over each band, and also agree well with the measured value at 6.175GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.7
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• pp.669-676
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• 2003

In this paper, a novel design method for an ultra-wide band TEM horn antenna is proposed on the basis of parallel plate waveguide theory. A principle of TEM modes generation is analyzed and the characteristics of this antenna are experimentally investigated. The proposed TEM horn antenna has an exponentially tapered structure to increase matching bandwidth. Also, the designed TEM horn has shortened length but increased aperture so that the bandwidth for cutoff frequency is increased. The measured result show that the proposed TEM hem antenna has the frequency band of 75 MHz to 1200 MHz for VSWR less than 2.0 and the bandwidth of the TEM horn becomes more than twice comparing to that of a linearly tapered TEM hem. It is anticipated that the manufactured antenna is applicable to UWB systems for impulse response measurement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.10
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• pp.1011-1016
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• 2003

In this paper, we investigate the relationship between the intermodulation signal of 2-tone and CDMA spurious emission of HPA. And confirm that the fifth IMD signal of HPA has more important effect upon CDMA ACPR characteristics than the third IMD signal. We present the method for the power amplifier to satisfy the 2-tone and CDMA specification simultaneously, and that is to use the predistorter for improving the third IMD signal of 2-tone for the power amplifier which is tuned to satisfy the CDMA specification and not to satisfy the 2-tone specification. The result by using the method which is presented from this paper shows that the ACPR is improved about 2 dB for CDMA 1FA(frequency allocation) signal and the third IMD signal is improved about 20 dB for CW 2-tone signals and we confirmed the specification is satisfied simultaneously.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.45-51
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• 2006

In this paper, a new predistortion linearizer for controlling the amplitude of low frequency intermodulation distortion signals is proposed. The low frequency intermodulation distortion(IMD) components are generated by harmonic generator. A vector modulator, modulate fundamental signal with low frequency IMD signals, generates predistortion IMD signals and controls amplitude and phase of them with modulation factors. As a result, this predistorter is suppressed IMD signals of power amplifier effectively. The predistortion linearizer has been manufactured to operate in cellular base-station transmitting band($869{\sim}894\;MHz$). The experimental results show that IMD3 of power amplifier are improved more than 20 dB for CW two-tone signals. Also, it's improved the adjacent channel power ratio(ACPR) more than 10 dB for IS-95 CDMA IFA signals.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.8
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• pp.943-953
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• 2007

In this paper, we propose a Cassegrain antenna with a scalar feed horn opt rating in Ka-band. For an effective EM simulation of the Cassegrain antenna, the near-field of the feed hone is used ai the equivalent source of the Cassegrain antenna using the surface equivalent theorem. A corrugated circular horn operating with $HE_{11}$ mode is used as the feed horn. The angle and feed center of the main and sub reflectors are optimized to achieve maximum antenna efficiency. The designed feed horn shows the gain of 19dBi, the side-lobe level of less than -25dB and the half power beam width of $20^{\circ}$ at 33 GHz. The Cassegrain antenna shows the gain of 41dBi, the efficiency of 60%, the side-lobe level of less than -20dB and the half power beam width of $1.2^{\circ}$.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.12
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• pp.2609-2614
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• 2010

Temperature compensation circuit is implemented by using the temperature sensor, and Intermodulation (IM) Specification of Power Amplifier is satisfied in the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$ with this temperature compensation circuit. The output voltage of temperature compensation circuit which vary 170mV with the temperature is applied to the gate of TR in 3W output power Amplifier. As the result, right 3rd IM component is -18.5~-26dBm, left 3rd IM component is -18.5~-35dBm, and the left and right 5th IM component is -24~-26dBm in the temperature range of $-30^{\circ}C{\sim}60^{\circ}C$. It is confirmed that IM specification of power amplifier which is under -17dBm in the whole temperature range is satisfied.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.11
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• pp.1672-1678
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• 2022

In this paper, the relay antenna was designed in consideration of the performance of the 28GHz band 5G mobile communication relay horn antenna, such as radiation pattern and return loss. A horn array for 5G mobile communication repeater was designed by arranging the antenna elements in phase, and the performance was analyzed. Unlike conventional WCDMA (3G) and LTE (4G), in millimeter wave band communication, high path loss occurs between transmission and reception. In the design of a 5G millimeter wave horn antenna, antenna performance such as isolation and gain between antenna elements as well as gain and bandwidth of the antenna must be additionally considered. The antenna gain of the single horn antenna (1×1) and the array horn antenna (2×4) in the 28GHz band is about 10.44d Bi and 19.58dBi, respectively, and the return loss is designed to be less than -18dB. It has proven its validity and has been shown to be suitable for application to 5G mobile communication relay system.

• Journal of Korean Home Economics Education Association
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• v.24 no.4
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• pp.1-18
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• 2012

This study investigated the mate selection preferences of single female teachers by investigating the desired traits in socioeconomic, physical attractions, psychological traits and family roles of their prospected marital partner, in order to explore the current trends in homogamous marriage. A questionnaire was distributed to 295 unmarried female teachers selected by convenience sampling from the various cities. The teachers pursued homogeneity in age, educational attainment, religion, and occupation while they preferred partners with higher income level. In terms of physical assets, the attraction that the teachers felt towards the partner was the most important physical appearances. The respondents preferred partners who are masculine and an androgynous partner. The teachers held high expectations towards their future spouses in that they desired to share the roles of emotional, financial support, child care and kin keeping. A partner who shared modern sex role attitudes was preferred over someone who held traditional one. The pursuit for overall homogeneity reflects that the teachers seek for equality in their relationships with prospected marital partners by exchanging similar characteristic.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.41 no.10
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• pp.97-102
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• 2004

In this paper, a new predistorter controlling modified individual order jntermodulation distortion signals is proposed. The proposed predistorter generates and controls predistorted third and high order IM signals independently. Using predistorted signals, jntermodulation distortion signals of power amplifier are suppressed effectively. The predistortion linearizer has been implemented to operate in Korean PCS basestation transmitting band (1840～1870MHz). The test results show that IMD3 and IMD5 (C/I) of power amplifier are improved more than 40dB and 23dB for CW two tone signals, respectively. The predistorter improves the adjacent channel power ratio (ACPR) more than 10dB at 885KHz offset point for CDMA (IS-95) signals.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.12A
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• pp.1019-1024
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• 2003

In the thesis, we propose a new type of the predistortion linearizer using frequency multiplier The linearizer utilizing the 2nd and 3th harmonic used the individual control of the 3rd and 5th order intermodulation distortion(IMD) component. This structure is composed of wilkinson power combiner for combine and isolation of output signal, 3rd order IMD product controller using doubler and 5th order IMD product controller using tripler. The proposed predistortion linearizer controlled by individual order is obtained for about -16 dBc and 18 dBc of 3rd order and 5th order IMD components, respectively, over the frequency band 870 MHz to 880 MHz at the output power of 34 dBm/tone.