완전 디지털 능동위상배열 안테나의 효과적인 부엽 차단 빔 형성 방법

주정명,박종국,임재환,이재민 한국인터넷방송통신학회 2022 한국인터넷방송통신학회 논문지 Vol.22 No.4

In this paper, a digital active phased array antenna is briefly introduced and beam forming method for a dual-channel side-lobe blanking applied to blank the side-lobe of the main beam is described. Next, the antenna performance was verified from results of design and antenna near-field measurement for the antenna main beam and side-lobe blanking beam. Then, a single-channel side-lobe blanking beam forming method was proposed to reduce the number of channels than the existing system operating dual-channel side-lobe blanking beam and weight distribution for each element of the side-lobe blanking antenna was designed with the proposed method. Finally, the designed single-channel side-lobe blanking beam pattern and blanking ability were verified and compared with the dual-channel side-lobe blanking beam. In addition, by comparing/verifying the conventional dual-channel and the proposed single-channel side-lobe blanking beam patterns measured through the receiving near-field test of the digital active phased array antenna and their ability to blank side-lobe of the main beam, validity of the proposed method for forming single-channel side-lobe blanking beam was confirmed. 본 논문에서는 디지털 능동위상배열 안테나를 간략히 소개하고 주 빔의 부엽을 차단하기 위해 적용된 이중 채널부엽 차단 빔 형성 방법에 대해 기술하였다. 그리고 안테나 주 빔 및 부엽 차단 빔 설계 결과와 안테나 근접전계 측정결과로부터 안테나 성능을 검증하였다. 다음으로 기존의 이중 채널 부엽 차단 빔 운용 방식 보다 채널수를 줄이기 위해단일 채널 부엽 차단 빔 형성 방법을 제안하고, 제안한 방법으로 부엽 차단 안테나에 대한 소자별 가중치 분포를 설계하였다. 마지막으로 설계된 단일 채널 부엽 차단 빔 패턴과 차단 능력을 검증하고 이중 채널 부엽 차단 빔과 비교하였다. 또한, 디지털 능동위상배열 안테나의 수신 근접전계 시험을 통해 측정한 이중 채널 부엽 차단 빔과 제안된 단일 채널부엽 차단 빔 패턴 및 부엽 차단 성능을 비교/검증함으로써 제안된 부엽 차단 빔 형성 방법에 대한 유효성을 확인하였다.

Estimation and suppression of side lobes in medical ultrasound imaging systems

권성재,정목근 대한의용생체공학회 2017 Biomedical Engineering Letters (BMEL) Vol.7 No.1

This paper estimates the side lobe levels fromthe received echo data, and proposes and compares threetypes of filters that can be used to suppress them in anultrasound image. Ultrasound echo signals from the offaxisscatterers can be modeled as a sinusoidal wave whosespatial frequency in the lateral direction of a transducerarray varies as a function of the incident angle. Thereceived channel data waveform due to side lobes have aspatial frequency of an integer plus a half. Doubling thelength of the channel data by appending zeros and takingthe discrete Fourier transform of the elongated data makesthe spatial frequency of the channel data due to side lobesbecome an integer. Thus, it is possible to estimate thecomplex amplitude of the side lobes. Adding together allthe channel data of the estimated side lobes, we can obtainthe side lobe levels present in ultrasound field characteristics. We define the summed value as a quality factor thatis used as a parameter of side lobe suppression filters. Computer simulations as well as experiments on wires in awater tank and a cyst phantom show that the proposedfilters are very effective in reducing side lobe levels andthat the amount of computation is smaller than that of theminimum variance beamforming method while showingcomparable performance. A method of estimating andsuppressing side lobes in an ultrasound image is presented,and the performance of the proposed filters is found to beviable against the conventional B-mode imaging andminimum variance beamforming methods.

A new method for assessing the performance of signal processing filters in suppressing the side lobe level

정목근,권성재 대한초음파의학회 2021 ULTRASONOGRAPHY Vol.40 No.2

Purpose: This study aimed to propose a new ground truth ultrasound imaging method and to confirm its efficacy when applied to side lobe suppression filtering. Methods: Using a computer simulation, we synthesized a side lobe-free image (i.e., with no side lobe whatsoever) by separating the main and side lobe signals in the construction of point target, speckled cyst, and pseudo-kidney images. During signal processing, we assessed the quality of the filtered image by comparing it with a ground truth image (i.e., the main lobe image). Results: We examined the effect of reducing the side lobe by applying aperture apodization, side lobe estimation and reduction filtering, and minimum variance beamforming, which are widely used as side lobe suppression techniques. Despite the drawback of decreased resolution, the commonly used apodization method increases the contrast, which improves ultrasound image quality and enables a better diagnosis. Although side lobe estimation and reduction filtering and minimum variance beamforming are demanding in terms of computational resources, they can considerably improve ultrasound images. Compounding of ultrasound images processed by various signal processing methods increases the resolution and contrast, while reducing the speckle noise. Conclusion: Although it appears that the proposed method can only be used for computer�generated radiofrequency data, this method can improve ultrasound image quality by identifying the characteristics of signal processing filters for side lobe suppression and applying appropriately adjusted filters to in vivo human imaging data.

Overlap Margin 확보 및 Side-lobe 억제를 위한 Scattering Bar Optical Proximity Correction

이흥주 한국산학기술학회 2003 한국산학기술학회논문지 Vol.4 No.1

Attenuated PSM lithography 공정에서 overlay margin 확보 및 side-lobe 제거를 위해 기존의 Cr shield 방식의 단점인 복잡한 mask 제작공정과 구조를 단순화하기 위한 방법으로 scattering bar 방식을 제안하였다. Scattering bar는 Cr 보조패턴처럼 완전히 빛을 차단하는 것이 아니라 약간의 빛을 투과시켜 보강된 intensity를 상쇄하므로 side-lobe를 억제하는 방법으로 metal pattern을 생성할 때 scattering bar도 동시에 만들어 mask제작에 필요한 공정횟수를 줄이고 mask구조 역시 단순하게 한다 그리고 동시에 DOF(depth of focus)를 향상시킨다. Background clear pattern의 경우에 발생하는 side-lobe도 scattering bar를 이용하여 효율적으로 제거되었다. Overlap Errors and side-lobes have been simultaneously solved by the rule-based correction using the rules extracted from test patterns. Lithography process parameters affecting attPSM lithography process have been determined by the fitting method to the real process data. The correction using scattering bars has been compared to the Cr shield method. The optimal insertion rule of the scattering bal's has made it possible to suppress the side-lobes and to enhance DOF at the same time. Therefore, in this paper, the solution to both side-lobe and overlap Error has been proposed using rule-based confection. Compared to the existing Cr shield method, the proposed rule-based correction with scattering bars can reduce the process complexity and time for mask production.

Low Side-Lobe Substrate-Integrated-Waveguide Antenna Array Using Broadband Unequal Feeding Network for Millimeter-Wave Handset Device

Seong-Jin Park,Dong-Hun Shin,Seong-Ook Park IEEE 2016 IEEE transactions on antennas and propagation Vol.64 No.3

<P>A low side-lobe substrate-integrated-waveguide (SIW) antenna array is presented at the 28-GHz band using broadband unequal feeding network for millimeter-wave (mm-wave) handset devices. The ground-plane size of the proposed antenna is fixed to half of the size of the Samsung Galaxy Note 4. The antenna array has been implemented with a multilayer structure created by stacking three substrates and a copper plate. An 8-way SIW feeding network with broadband 4-stage T-junction dividers and a cavity-backed antenna are investigated to obtain broadband performance. The proposed unequal T-junction dividers with phase compensation are introduced and designed for various output ratios. Applying Taylor beam-pattern synthesis in the 8-way SIW feeding network, low side-lobe performance is achieved. The measured result of the fabricated antenna has 2.3 GHz bandwidth within S<SUB>11</SUB> <; - 10 dB. The fabricated antenna can be performed with a gain up to 13.97 dBi with a low cross-polarization and symmetrical fan beam radiation patterns with low side-lobe levels. Most of the measured results are validated with the simulated results. The proposed antenna array provides low cost, broadband performance, and good radiation performances with low side-lobe levels for mm-wave handset devices.</P>

ADCP를 이용한 유량측정에서 side-lobe현상 개선 연구

정승교(Jeong, Seung Gyo),황재성(Hwang, Jae Sung),이신재(Lee, Sin Jae) 대한토목학회 2020 대한토목학회 학술대회 Vol.2020 No.10

ADCP(Acoustic Doppler Current Profiler)는 유수의 흐름을 방해하지 않으면서 수중에 발사된 음파의 도플러 효과를 이용하여 3차원 유속 측정이 가능한 초음파 유량측정장비이다. 이에 최근 국내에서는 ADCP를 이용한 유량측정이 증가하고 있다. 하지만 ADCP를 이용한 유속 또는 유량측정을 수행하다 보면 수중 식생에 의한 오측 및 결측 등이 발생하여 측정된 자료의 불확도가 증가하게 된다. ADCP에서 수중에 발사한 음파 중 식생에 부딪친 강한 반사파의 노이즈로 side-lobe현상에 의한 오측 및 결측이 발생한다. 현재 오측 및 결측 자료는 ADCP 제조사별 자료 취득 소프트웨어의 기능에 의존 하거나, USGS의 OSW(Office of Surface Water) Hydroacoustics의 QRev를 이용하여 후처리 과정을 거쳐 측정 자료로 정리하고 있다. 이에 본 연구에서는 노이즈로 인한 side-lobe현상을 물리적인 방법으로 제거하기 위해 음향 녹음 과정에서 노이즈를 물리적인 방법으로 제거하는 윈드실드와 팝 필터를 고려한 ADCP필터를 개발하여 적용하였다. 그 결과 side-lobe현상에 의한 오측 자료들이 많이 개선되는 결과를 보였다.

초음파 영상에서 나타나는 측엽에 의한 허상(Side-lobe artifact)의 발생기전과 임상적 고찰

강대현,이성현,김유현 高麗大學校 倂設 保健大學 保健科學硏究所 2000 保建科學硏究論集 Vol.9 No.1

Many artifacts are commonly occurred in clinical ultrasound imaging. Among these artifacts, the side lobe artifacts are especially important because it can be make a mistake to some materials or sludge in organs such as the gallblader and urinary bladder, to in abnormal masses. Experimentally done to permitted the occur of these side lobe artifacts and clinical examples were analyzed to improvement diagnostic accuracy in ultrasound imaging. The results of study are as followings: 1. Side lobe artifacts are occurred to strong specular echoes at the inner wall of plastic case, when the sonographic equipment out put power or gain increased. 2. Diffuse artifacts ocurred at the high reflective bowel gas nearly contact to cystic organs, such as gallbladder or urinary bladder. 3. To remove these uneffective artifacts, reducing the ultrasound equipment output power, repositioning the patient, changing the transducer angulation etc. are proved to be effective.

Correction Simulation for Metal Patterns on Attenuated Phase-shifting Lithography

이흥주,이준하 한국전기전자재료학회 2004 Transactions on Electrical and Electronic Material Vol.5 No.3

Problems of overlap errors and side-lobe printing by the design rule reduction in the lithography process using attenuated phase-shifting masks(attPSM) have been serious. Overlap errors and side-lobes can be simultaneously solved by the rule-based correction using scattering bars with the rules extracted from test patterns. Process parameters affecting the attPSM lithography simulation have been determined by the fitting method to the process data. Overlap errors have been solved applying the correction rules to the metal patterns overlapped with contact/via. Moreover, the optimal insertion rule of the scattering bars has made it possible to suppress the side-lobes and to get additional pattern fidelity at the same time.

Correction Simulation for Metal Patterns on Attenuated Phase-shifting Lithography

Lee, Hoong-Joo,Lee, Jun-Ha The Korean Institute of Electrical and Electronic 2004 Transactions on Electrical and Electronic Material Vol.5 No.3

Problems of overlap errors and side-lobe printing by the design rule reduction in the lithography process using attenuated phase-shifting masks(attPSM) have been serious. Overlap errors and side-lobes can be simultaneously solved by the rule-based correction using scattering bars with the rules extracted from test patterns. Process parameters affecting the attPSM lithography simulation have been determined by the fitting method to the process data. Overlap errors have been solved applying the correction rules to the metal patterns overlapped with contact/via. Moreover, the optimal insertion rule of the scattering bars has made it possible to suppress the side-lobes and to get additional pattern fidelity at the same time.

Increase of Side-lobe Level Difference of Spherical Microphone Array by Implementing MEMS Sensor

Jaehyung Lee(이재형),Sihong Choi(최시홍),Jong-Soo Choi(최종수) 한국소음진동공학회 2011 한국소음진동공학회 학술대회논문집 Vol.2011 No.4

본 논문은 구형 마이크로폰 어레이의 부엽 레벨의 차를 증가시키기 위한 방법에 대한 연구 내용을 다루었다. 일반적인 어레이 신호처리에서 마이크로폰을 조밀하게 배치함으로써 어레이 응답에서의 주엽과 부엽 간의 차이를 늘릴 수 있고 어레이의 소음원 판별능력을 증가시킨다. 최근 사용되고 있는 상용 에레이들은 제작 단가와 어레이의 크기 때문에 센서의 수를 늘리는데 한계를 보이고 있다. 이런 문제를 극복하기 위해 본 연구에서는 MEMS 센서를 이용하여 구형 어레이에 적용하였다. 구형 마이크로폰 어레이를 이용한 시뮬레이션과 실험을 통해 정현파 소음원을 측정하였다. 실험을 위해 32 개의 일반 측정용 마이크로폰을 이용한 어레이와 85 개의 MEMS 마이크로폰을 이용한 구형 어레이를 제작하였다. 구형 조화 분해기법과 빔형성기법을 이용하여 측정 데이터를 분석하였다. 2 kHz 이상의 소음원에 대하여 MEMS 마이크로폰 어레이가 4 dB 이상의 부엽 저감 능력을 가지는 것을 확인하였다. A method for increasing the difference of side-lobe level in spherical microphone array is presented. In array signal processing, it is known that narrow interval between sensors can increase the difference between main lobe and side-lobe of array response which eventually increase the source recognition capability. Recent commercial array being used, however, have shown certain limitation in using the number of sensors due to its costs and geometrical size of array. To overcome this problem, we have adapted MEMS sensors into spherical microphone array. To check out the improvement, two different types of spherical microphone array were designed. One array is composed with 32 regular instrument microphones and the other one is 85 MEMS sensors. Simulation and experiments were conducted on a sinusoidal noise source with two arrays. The time history data were analyzed with spherical harmonic decomposition and beamforming technique. 85 MEMS sensors array showed the improved side-lobe level suppression by more than 4 dB above the frequency content of 2 kHz compared to 32-sensor array.