• ETRI Journal
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• v.42 no.3
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• pp.333-340
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• 2020

We consider a hybrid combiner design for downlink massive multiple-input multiple-output systems when there is residual inter-user interference and each user is equipped with a limited number of radio frequency (RF) chains (less than the number of receive antennas). We propose a hybrid combiner that minimizes the mean-squared error (MSE) between the information symbols and the ones estimated with a constant amplitude constraint on the RF combiner. In the proposed scheme, an iterative alternating optimization method is utilized. At each iteration, one of the analog RF and digital baseband combining matrices is updated to minimize the MSE by fixing the other matrix without considering the constant amplitude constraint. Then, the other matrix is updated by changing the roles of the two matrices. Each element in the RF combining matrix is obtained from the phase component of the solution matrix of the optimization problem for the RF combining matrix. Simulation results show that the proposed scheme performs better than conventional matrix-decomposition schemes.

• ETRI Journal
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• v.16 no.1
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• pp.59-72
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• 1994

In this paper, a new N-way hybrid power combiner for improving the graceful degradation performance has been proposed. The proposed combiner has been configured with two dummy transmission lines per each section, where each dummy transmission line has a different characteristic impedance, of the standard combiner. Under this proposed configuration, a detailed theoretical analysis has been performed to show the general function of a power combiner. When any M amplifiers among N identical amplifiers are suffering the failure mode in a power combining circuit or system, the graceful degradation performance has been improved due to the separation of a transmission line and an internal resistor in every failed section from the proposed combiner by simultaneously operating two shorting devices. Simulation results for all the items which can be measured from all the items which can be measured from the proposed combiner with an eight-way configuration have been presented.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.2
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• pp.227-232
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• 2009

The simple PSK signal generation method using a quadrature hybrid coupler and reflection coefficient elements was analyzed in this paper. The PSK modulation signal with a constant constellation is generated by reflection coefficient from 90o hybrid coupler output ports, the high-mode PSK signal is also generated by the hybrid structure of coupler, delay line and power combiner. The BPSK signal is simply generated by a 90o hybrid coupler and reflection elements, and QPSK with 90o phase constellation is generated by additional delay line and power combiner. By simulation results, the generated PSK signals by the proposed circuit get good modulation spectra within 3o phase error.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.8
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• pp.1415-1423
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• 2007

Total efficiency of transmitter system was improved by developing combinational 2-Way Isohybrid for GSM1900 base station in this paper. The size of product was decreased and the characteristics were stabilized. The isohybrid transmitter combiner of chip coupler type and hybrid coupler type were designed and fabricated. Insertion loss for chip coupler type isohybrid was $3.17\;dB{\sim}3.47\;dB$. On the other hand, insertion loss for hybrid coupler type was $3.17\;dB{\sim}3.42\;dB$. Isolations between ANT and port were $24.23\;dB{\sim}29.98\;dB$ in case of chip coupler type Isohybrid and were $26.28\;dB{\sim}36.91\;dB$ in case of hybrid coupler type, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.6
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• pp.579-589
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• 1989

In this paper, planar power dividers/combiners for millimeter waves K-band or bands which can be printed on the substrates of hybrid or monolithic IC by surface mounting are designed and studied. Power dividers/combiners, and the conductor loss of microstrip lines in particualr the existing Wilkinson power dividers/combiners is modified ad amployes by ist equivalent circuit. Microwave CAD program SUPEROMPACT is employed for the Wilkinson power combiner which is modified and analyzed to reduce the high frequency coupling between the branches of the combiner, and the method to diminish the sensitivity of the input reflection of $2^n$-way power dividers/combiners is studied employing the commerical microwave CAD program package SUPERCOMPACT.

• International Journal of Industrial Entomology and Biomaterials
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• v.13 no.2
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• pp.73-77
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• 2006

Combining ability and hybrid vigour analysis was carried out in hybrids between newly developed non-susceptible lines to BmDNV1 and popular bivoltine breeds for certain quantitative traits viz. Pupation rate, Cocoon yield, Cocoon weight, Cocoon shell weight and Cocoon shell ratio, Survival rate against BmIFV and BmNPV. General combining ability (GCA) effects revealed that among the lines CSR2DR was found good general combiner exhibiting significant GCA effects for six characters, out of seven traits evaluated. Among testers CSR28DR was found as good combiner exhibiting significant GCA effects for six traits. Out of 36 hybrids made between $resistant{\times}resistant,\;resistant{\times}susceptible\;and\;susceptible{\times}susceptible$ breeds, one hybrid $CSR21DR{\times}CSR28DR$ exhibited significant SCA effects for six traits. The selected hybrid $CSR21DR{\times}CSR28DR$ also exhibited significant positive heterosis and heterobeltiosis expressions for maximum traits and could be exploited as commercial silkworm hybrid resistant to important viral diseases.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.4
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• pp.575-581
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• 2000

In this paper, a new active phase shifter is proposed using a vector sum method, and a unique digital phase control method of the circuit is suggested. The proposed scheme was designed and implemented using a Wilkinson power combiner/divider, a branch line 3 dB quadrature hybrid coupler and variable gain amplifiers (VGAs) using gate FETs(DGFETs). Furthermore, it was also shown that the proposed scheme is more efficient and works properly with the digital phase control method.

• 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%.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.178-182
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• 2004

In this paper, a 90$^{\circ}$ hybrid coupler with both power division and harmonic rejection characteristics is presented by applying a LPF characteristic to a conventional 90$^{\circ}$ hybrid. Since a conventional 90$^{\circ}$ hybrid coupler operates as a power divider/combiner using phase difference, it does not suppress higher order harmonics when it is incorporated with nonlinear amplifier. This requires an additional filter to take into account of the harmonics. The proposed 90$^{\circ}$hybrid coupler power provides the division capability and proper phase difference, as well as harmonic suppression characteristic by integrating LPF characteristic.

• International Journal of Industrial Entomology and Biomaterials
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• v.13 no.2
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• pp.63-72
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• 2006

Parthenogenesis, the development of unfertilized ovum opens new perspectives in silkworm breeding in the development of homozygous breeds. In order to improve induction of artificial parthenogenesis in the excised unfertilized eggs of different breeds of the silkworm, Bombyx mori L., a new method was devised and the results were compared with the routine method. General and specific combining abilities and hybrid vigour of newly developed bivoltine breeds were analyzed utilizing bivoltine breeds viz., $CSR_2,\;CSR_4,\;CSR_{17}\;and\;NB_4D_2$ Estimation of GCA revealed superiority of the breeds, $DNB_1$ for eight characters followed by $DNB_4$ for five characters. Among the testers, $CSR_2$ was found good general combiner for seven characters followed by $CSR_{17}$ for four characters. A great deal of variations was observed among the hybrids studied. Five hybrids namely, $DNB_1{\times}CSR_2,\;DNB_4{\times}CSR_4,\;DNB_4{\times}NB_4D_2,\;DNB_6{\times}CSR_2\;and\;DNB_7{\times}CSR_2$ showed significant SCA effects for 5-6 characters. The hybrid, $DNB_4{\times}CSR_4$ showed its superiority by expressing significant hybrid vigour over BPV for 7 characters. Majority of the hybrids exhibited significant hybrid vigour for survival rate, yield/10,000 larvae by weight, cocoon weight, cocoon shell weight, filament length and denier.