• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.4
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• pp.360-368
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• 1988

A 14 to 14.5 GHz low noise MIC amplifier is designed on the $Al_2$$O_3$ substrate. The amplifier which uses a GaAsMESFET developed at COMSAT Laboratories has been designed and optivized to have gain greater than 7dB and noise figure less than 2dB using Super-Compact program. Experimental results show that the gain of the amplifier is 7 to 7.7 dB, while noise figure is 3.8 to 4.3dB through the desired band.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.920-927
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• 1994

A development of an efficient 14.0~14.5GHz 3 Watt SSPA is described in this paper, which is applicable to the very small aperture terminal(VSAT) for bidirectional data and voice signal transmission in low cost and with small size. The SSPA consists of two stages of low noise amplifiers using the low noise GaAs FETs. two stages of medium power amplifiers using the medium power GaAs FETs, and three stages of power amplifiers including a balanced amplifier using an internally matched power GaAs FET. The achieved with this seven stage amplifiers are 42dB signal power gain, 7dB noise figure, 35dBm output power at 1dB gain compression point and 2.0 and 1.5 input and output VSWR respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8B
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• pp.1341-1347
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• 2000

For the DRT satellite transponder system, BER and total SNR to be required in the earth terminal are evaluated under the condition of HPA nonlinearity in the FBJ(full-band jamming) or PBJ(partial-band jamming) of uplink and downlink. In case that the satellite Inter bandwidth( Ws) is same to the earth terminal bandwidth($W_r$),in conditions of uplink JSR 10[dB], downlink JSR 10[dB] and processing gain 30[dB], linear transponder system shows that uplink SNR needs to be 14.2[dB] to achieve the total SNR 10[dB] requirement in downlink SNR 14[dB]. However, Nonlinear transponder system with OBO(output backoff) 2[dB] requires 20.1 [dB] uplink SNR. From the above results, the nonlinearity of HPA in the satellite transponder causes the degradation of BER performance so that it is of interest to consider the power increase.

• Journal of Broadcast Engineering
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• v.12 no.6
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• pp.641-648
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• 2007

The decoding structure of up-to-date ATSC DTV receivers is well optimized, and it seems that 14.6 dB is the unbreakable minimum SNR in the AWGN channel. But the SNR satisfying the Shannon capacity of DTV receivers is 11.76 dB, So, the SNR gab between the 14.6 dB and the 11.76 dB is about 2.8 dB. In order to approach the Shannon capacity we propose a recursive trellis decoder which uses reliable feedback data obtained by an RS decoder. The performance enhancement of about 0.8 dB can be achieved in case of the AWGN channel.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.7 no.1
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• pp.53-60
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• 1996

The 8W hybrid MIC SSPA has been developed in the frequency range from 14.0 GHz to 14.5 GHz for uplink of KOREASAT's earth station. The whole system was designed of two parts with driving amplifier and high power amplifier to simplify the fabrication process. we reduced weight and volum of power amplifier through arranging the bias circuits in the same housing. The realized SSPA has a small signal gain of $26\pm1dB$within 500 MHz bandwidith, and the input and output return losses are over 7dB and 12dB respectively. The output power of 39.0 ~ 39.2dBm is achieved at the 1dB gain compression point of 14 GHz, 14.25 GHz, and 14.5 GHz. That reveals higher power than 8W of design target. The proposed SSPA manufacture techni- ques in this paper can be applied to the implementation of power amplifiers for some radars and SCPC.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.45 no.1
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• pp.110-114
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• 2008

In this paper, high efficient class F power amplifier with dual band has been realized. Dual band power amplifier have used modify stub matching for single FET, center frequency 2.14GHz and 5.2GHz respectively. Dual band amplifier is 32.65dBm output power, gain 11dB and PAE 36% at the 2.14GHz, 7dB gain at the 5.2GHz. Design of a dual band class F power amplifier using harmonic control circuit. The measured are 9.9dB gain, 30dBm output power and PAE 55% at the 2.14GHz, 11.7dB gain at the 5.2GHz. This paper is being used the load-pull method and it maximizes output power and it is using the only one transistor in the paper. As a result, this research will obtain a dual band high PAE power amplifier.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.5
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• pp.872-882
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• 1994

In this paper, the Low Noise Amplifier(LNA) is designed and fabricated to include a band pass filter characteristics considering the antenna system characteristics according to the transmitting and receiving signal level of communication satellite transponder. As an example, a 2-stage low noise amplifier and a 4-stage amplifier and designed, fabricated and measured at 14,0~14.5GHz of receiving frequency band. This fabricated LNA has shown the gain with very good flatness within pass-band, and its gain decreases rapidly out of band resulting in supperssion of the transmitting signal power leakage. It has shown the 20.3dB +- 0.1dB of pass-band gain, the 1.44dB +-0.04dB of noise figure and the 14dB rejection out of band(12.25~12.75GHz). The gain flatness, noise figure and group delay of this 2-stage LNA satisfactorily met the simulation results. And the fabricated 4-stage amplifier has shown the more than 42dB of pass-band gain, the +-0.25dB of flatness and the 28dB of the rejection effect for transmitting power leakage. The 2-stage LNA and 4-stage amplifier, in this paper, will bring a design margin for the input filter and also result in the system cost reduction.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.1
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• pp.13-22
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• 2022

In this paper, we propose single and array antenna with dual linear polarization characteristics for 28 GHz band. The proposed antenna is designed two microstirp feeding structure and Taconic TLY-5 substrate, which is thickness 0.5 mm, and the dielectric constant is 2.2. The size of single patch antenna is 3.4 mm×3.4 mm, and total size of single antenna is 15.11 mm×15.11 mm. Also, the size of array antenna is 3.15 mm×3.15 mm, and total size of array antenna is 21.5 mm×13.97 mm. From the fabrication and measurement results, for 1×2 array antenna, in case of vertical polarization, cross polarization ratios are obtained from 14.23 dB to 20.79 dB and in case of horizontal polarization, cross polarization ratios are obtained from 14.31 dB to 22.74 dB for input port 1. in case of vertical polarization, cross polarization ratios are obtained from 15.75 dB to 25.88 dB and in case of horizontal polarization, cross polarization ratios are obtained from 14.70 dB to 22.82 dB for input port 2.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.7
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• pp.1433-1438
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• 2011

Relative attenuations of Tx and Rx in K-PCS and US-PCS duplexers were about -60dB and -65dB, -51dB and -53dB, respectively. In the case of Rx and Tx in K-PCS and US-PCS bandpass filters, relative attenuations were about -40dB and -14dB, -5dB and -10dB, respectively. From the aboved results, the relative affect between Tx and Rx in K-PCS bands was smaller than that of US-PCS bands. Also, the various capacitances of passband were important role to determine the characterics of bandpass filter.

• 전자공학회논문지 IE
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• v.45 no.4
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• pp.54-59
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• 2008

In this paper, circularly polarized patch antenna with 2-stage LNA for the reception of S-DMB is presented. It used teflon didelectric substrate of ${\in}_r$=2.2 and the size is $40{\times}40{\times}15\;[mm]$. Experimental results of fabricated antenna show that bandwidths of input return loss and axial ratio are about 22 [MHz] and 25 [MHz]. Input return loss, output return loss, gain, and noise figure of the fabricated 2-stage LNA are $S_{11}$=-14 [dB], $S_{22}$=-18 [dB], $S_{21}$=26.8 [dB], and NF=1.14 [dB] respectively. The fabricated active type antenna has total gain of 30.4 [dB] at 2.642 [GHz].