• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.428-431
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• 2003

In this paper, distances between elements are optimized for low sidelobe level (SLL) microstrip patch array using Genetic Algorithms. Genetic Algorithms are "global" numerical-optimization methods, it's advantages are very simple coding and fast optimization. This paper show how to optimize the maximum SLL using Genetic Algorithms. In the results, although mutual coupling is neglected, it's maximum SLL is 3.5 dB lower than Uniformly Spaced Array(distance=$0.5{\lambda}$).

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.21-25
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• 2014

Scan capabilities of Fabry-Perot cavity (FPC) antennas are investigated for the case of a $4{\times}1$ thinned array placed inside the cavity. The FPC array antenna has higher maximum gain and lower sidelobe level (SLL), but the maximum scan angle of the thinned array is 14-17% lower than the patch array alone, due to increased mutual coupling in the FPC structures. However, unlike the bare thinned array, the SLL of FPC array does not suffer from the grating lobe problem even though it has a relative large element spacing of more than $1.0{\lambda}_0$.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.9
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• pp.1025-1033
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• 2012

Fabry-Perot cavity(FPC) antennas with artificial magnetic conductor(AMC) surface are designed in order to provide scan capability by $4{\times}1$ array feed inside the cavity. The proposed antenna, excited by $4{\times}1$ thinned array, not only achieve higher directivities but also improve suppression of sidelobe level(SLL) relative to that of the thin array alone. The FPC antenna with the height of a quarter wavelength generate maximum gain of 19 dB, SLL suppression of 14 dB and maximum scan angle of $8^{\circ}$ under the feed phase difference of $90^{\circ}$ at the design frequency of 12 GHz.

• Journal of IKEEE
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• v.6 no.1 s.10
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• pp.40-46
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• 2002

In this paper, a microstrip array antenna is designed, fabricated and measured for ETCS(Electronic Toll Collection System). To reduce effect of external propagation environment, we use edge-cuffed element and to obtain wider axial ratio and increased bandwidth, we use the sequential rotation array method. Also to fulfill ETCS, roadside equipment are designed to be provide a radiation pattern which can accurately pinpoint the designated communication area without interference of another lanes. And we make and apply an absorber to the array antenna to reduce SLL(Side Lobe Level). From the measurement, we get that return-loss at center frequency is -20.675dB, axial ratio is 0.35dB and the gain is 20.26dBi. And we found that SLL is reduced.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.6
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• pp.449-456
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• 2018

Herein, several multibeam forming methods that can be applied to microwave wireless power transmission are presented. Because the conventional multibeam forming methods do not consider an active element pattern(AEP), an intended beam shape will contain a steering angle error when applied to an actual system. To solve this problem, a method of considering the average of the AEP and a method of considering all the AEPs by the modified Fourier series method have been proposed. We confirmed that the proposed method reduces the error with the intended beam shape in the multibeam formation. In addition, for the side lobe level(SLL) and null control, a method of multibeam forming by applying the superposition principle to the Dolph-Tschebyscheff method is proposed. We also confirmed that SLL control can be simultaneously achieved with the multibeam formation.

• 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.24 no.4
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• pp.357-365
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• 2013

The 4 by 4 series slot sub-array antenna is proposed using substrate integrated waveguide(SIW) technology for 35 GHz of Ka band application. The proposed antenna is realized with multi-layered structure for compact size and easy integration features. 4 by 4 radiating slots are arrayed on top PCB with equal spacing and the feeding SIWs are arranged on middle and bottom PCBs for uniform power distribution. The multi-layered antenna is realized using RT/Duroid 5880 that has dielectric constant of 2.2 and the total antenna size is $750.76mm^2$. The individual parts such as radiators and feeding networks are simulated using full-wave simulator CST MWS. Furthermore, the total sub-array antenna also fabricated and measured the electrical performances such as impedance bandwidth under the criteria of -10 dB(490 MHz), maximum gain(18.02 dBi), sidelobe level(SLL)(-11.0 dB), and cross polarization discrimination (XPD)(-20.16 dB).