• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.4
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• pp.449-456
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• 2012

Herein, we design a wideband $8{\times}8$ waveguide Butler matrix in order to use in a multi-port amplifiers(MPAs) at Ka-band. To achieve the broadband characteristic, we design a binomial 6-slot 3 dB directional coupler which is used to configure the $8{\times}8$ Butler matrix. The measured results of the fabricated $8{\times}8$ Butler matrix have low insertion loss of less than 0.3 dB, good return loss of over 26 dB and high isolation of over 35 dB within the design bandwidth of 3 GHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.54 no.1
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• pp.11-17
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• 2017

In this paper, an 8-direction switched beamforming antenna system at 28GHz frequency band is described for 5th generation wireless communication. This system is composed of an $8{\times}8$ Butler matrix and an 8-element patch array antenna. The antenna system switches beams in 8-direction in the wide range of ${\pm}40^{\circ}$. The antenna spacing is $0.65{\lambda}$ to achieve ${\pm}40^{\circ}$ steering range. Designed results show that the 8-direction beams are placed at ${\pm}6^{\circ}$, ${\pm}17^{\circ}$, ${\pm}28^{\circ}$, ${\pm}40^{\circ}$ offset from the center. Parasitic radiation effect from the large dimension Butler matrix need to be suppressed by employing a stripline structure.

• Proceedings of the KAIS Fall Conference
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• 2010.05a
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• pp.18-23
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• 2010

4$\times$4 Butler Matrix structure has been presented in this paper. It can passes the signal with equal power level and phase difference in the 824MHz to 894MHz frequency of the cellular band. Conventional Butler Matrix was implemented as a single layer substrate structure, but in this paper, we use multi-layer substrate structure and eventually we could get it reduced in size than others. We also used the LTCC coupler to reduce the size effectively, instead of using $90^{\circ}$ hybrid coupler composed of microstrip structure. we used Designer V3.5 Ansoft HFSS V11 for design of 4$\times$4 Butler matrix. Finally, we get good agreements between simulation and experimental results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.11
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• pp.1687-1695
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• 2021

In this paper, it is designed and analyzed the beamforming antenna using the butler matrix. The operating frequency of the proposed beamforing antenna is ISM band of 2.4 GHz band and the component of the beamforing antenna consisted of a 1×4 array antenna and a 4×4 butler matrix. Each output port of 4×4 butler matrix outputs the signal having a different phase, it is provided to each input port of 1×4 array antenna. The beamforming antenna with four output ports forms a total of four beams. In order to analyze the radiation pattern of the beamforming antenna, it was provided by switching the signal to the input port and proceeded the Individual analysis for the input port 1 to 4. The main beams of the proposed beamforming antenna were formed in the -12°, 40°, -40° and 12° directions according to each input port, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.9
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• pp.563-565
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• 2014

Beam forming techniques are used to increase the efficiency of using frequency. In this paper we design and implement Butler matrix to be used for ISM band. The implemented Butler matrix has the insertion loss of maximum 6.7dB and the maximum phase shift error of $-6.51^{\circ}{\sim}7.17^{\circ}$ over 2.4~2.485GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.10
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• pp.876-884
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• 2015

In this paper, a switched beamforming antenna system at 28 GHz frequency band is described for $5^{th}$ generation wireless communication. The butler matrix is used as a beamforming system and it produces linear spaced phase difference at four output ports. Array antenna is designed that can be steered in desired 4 different directions 28 GHz frequency band. Operation of designed butler matrix that composed of couplers and feedline is explained. The antenna system is designed in RO3003 substrate that has a height of 5 mil and dielectric constant of 3. The size of butler matrix is $20.3{\times}13.0mm^2$ and size of array antenna is $21.2{\times}19.9mm^2$. This system can be steered from $-34^{\circ}$ to $33^{\circ}$ and minimum sidelobe level is 12.9 dB.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.6
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• pp.501-504
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• 2017

In this paper, a hybrid beamforming antenna system using broadband butler matrix and phase shifter is proposed. In the previous works, an $8{\times}8$ butler matrix is used to overcome a drawback of the $4{\times}4$ butler matrix based switched beamforming which provides only 4 beam patterns. However the $8{\times}8$ butler matrix should be designed on the bi-layered substrate using via holes due to its complex structure. It causes performance degradation. To overcome these problems, the proposed hybrid beamforming antenna system is designed on the single side of the substrate for simple structure. By addition of two phase shifter, it provide various beam patterns. The proposed antenna system provides more than 10 dBi radiation gain in the ${\pm}45^{\circ}$ scanning range by 16 input combinations.

• Proceedings of the Korea Contents Association Conference
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• 2016.05a
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• pp.13-14
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• 2016

LTE 대역인 2.5-2.68GHz에서 동작하는 버틀러 스위치를 설계하기 위해 버틀러 매트릭스의 구성요소인 3dB 하이브리드 커플러와 크로스오버를 다단 브랜치 선로의 구조로 구성하여 광대역 특성을 갖는 평면 구조의 버틀러 스위치를 설계하였다. 설계된 버틀러 스위치는 동작대역에서 23.9dB ~ 34.18dB의 좋은 반사손실 특성과 비교적 작은 $7.124^{\circ}$의 위상오차를 보였다.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.3
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• pp.200-205
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• 2014

In this paper, 5.8GHz band $4{\times}4$ Butler matrix is designed using easily accessible commercial $90^{\circ}$ hybrid coupler and semirigid coaxial cable as a transmission line. This Butler matrix is very flexible to changes of antenna system specification like a frequency band because $90^{\circ}$ hybrid coupler changing is all to do. The result of design is the distance of $2{\times}2$ array antenna element is $\sqrt{2}{\lambda}/4$, the 4 beam directions are diagonal of array antenna and phase shifter is not necessary. The beam width is roughly $25^{\circ}$ narrower because of array antenna geometry and the side lobe is about 10dB higher partially than theoretical beam pattern. But the overall beam pattern is similar with theoretical beam. This Butler matrix can be applied to switching beam antenna of 5.8GHz band Wi-Fi and WAVE system.

• Journal of Satellite, Information and Communications
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• v.11 no.4
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• pp.107-113
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• 2016

In this paper, we suggest a design method of a wide-band Butler matrix working at 5.9 GHz for V2X communication antennas. Since V2X communication needs beam-forming and beam-steering antennas to make transportation systems, mobile comm platforms, saturated frequency-resources, and signal TX-and-RX smart, multi-functional, resolved, and efficient utmost, respectively, the proper Butler matrix and its radiating elements as a low-profile geometry are realized. The constitutive components of the basic Butler matrix of a narrow band are designed first. And then, it is extended to a wide-band version to make its frequency-shift less affected by the event of the antenna system being mounted on a car body. The beam-forming and beam-steering performance is presented as the common feature tagged along with the different bandwidths of the frequency responses as the comparison between the narrow- and wide-band cases.