ANSYS Solutions for mmwave Antenna - ADAS, 5G, Military Kihyun Kong, Ph. D. Sr. Application Engineer ANSYS Korea 1
Outline 안테나설계를위한 HFSS Tips Unit Antenna Design 좀더정확한해석을위해서 ( 흡수경계조건 ) Array Synthesis (Estimation to full array) 전기적으로큰구조해석을위한 HFSS Solutions Adaptive Beamforming 제조공정을고려한시뮬레이션 2
Challenges of mmwave Antenna Engineering mmwave 는아직범용화되지않아경험이부족 파장이짧아물리적크기가너무작음 정밀한가공공정이필요로함 정확한 modeling & meshing 기반의시뮬레이션이필수 제작을고려한 Transition 구조에연구필요 특히 Signal Via 등에대한고품질 Meshing 필요 Propagation 손실이커서 고성능 / 고효율의안테나가필요 위상배열안테나뿐만아니라 Diversity 또는 MIMO 안테나시스템에대한고려도필요 mmwave 이상의대역에서는 Radome Effect 도고려해야함 안테나를포함하는제품은전기적으로큰구조물 3
안테나설계를위한 HFSS Tip #1 Unit Antenna Design 4
Array Antenna Design Procedure Single Antenna Element Synthesize Array Integrated Array with Module Unit Cell TRL Tool in 3D Layout Interface or Antenna Tool Kit (ACT Wizard) Finite Array Explicit Simulation With Feed Network Port1 5
HFSS Antenna Toolkit Antenna Toolkit Wizard R17 부터기본설치에포함 약 66 가지안테나모델 (6 가지 Array Model) Menu : View > ACT Wizard HFSS Antenna Toolkit 실행 입력 : Center Frequency Outer Boundary Substrate Dimensions Synthesis Antenna Dimension 이자동계산 Finish 자동으로변수처리된안테나모델링및결과 Template 이생성 6
HFSS Antenna Toolkit 안테나 모델의 Dimension이 모두 변수 처리되어 있으며, 변수에 대한 정의는 Antenna Toolkit Wizard의 Help 그림에서 참조할 수 있음 7
Estimation in 3D Layout Patch Dimension Estimation Define Stackup Menu : Layout > Layers Estimation Menu : HFSS 3D Layout > Estimate Layer 정보 ( 두께, 재질 ) 입력후 Patch Length/Width 및 50ohm Impedance 지점을미리계산해볼수있음 8
2D MoM Solver in 3D Layout 3D Layout : 2D MoM 4 Element Aperture Coupled Feed Patch Array Example 9
안테나설계를위한 HFSS Tip #2 좀더정확한해석을위해서 ( 흡수경개조건 ) 10
ABC or PML? HFSS 의해석대상바깥영역 (Background) 은 Perfect Conductor 로가정하며대부분의경우 Air( 또는 Vacuum) Box 를만들고경계면에흡수역할을하는경계조건을설정 흡수경계조건의종류 Radiation Boundary (ABC) Perfect Matched Layers (PML) FE-BI Antenna 의경우흡수경계조건의특성을알고사용하는것이정확한해석에도움 11
Guide-lines of Radiation BC (ABC) Distance from radiating structure Place at least /4 from strongly radiating structure Place at least /10 from weakly radiating structure Distance Test : λ/20, λ/10, λ/8, λ/4, λ/2, 3 λ/4, λ 0.2 db variation /4 and cases within 13 MHz of each other (0.1%) 12
Guide-lines of Perfect Matched Layer(PML) Distance from radiating structure Place at least /8 from radiating structure (Recommend) Distance Test : λ/20, λ/10, λ/8, λ/4, λ/2, 3 λ/4, λ λ /8 and 3 λ /4 cases within 28 MHz of each other (0.3%) 13
Large Incidence Angle Normal Incidence Incident Angle Dependencies ABC PML Reflection Effect ABC functions well for incident angles less than 25-30 PML functions well for incident angles less than 65-70 14
FE-BI FEM Solution in Volume Fields at outer surface IE Solution on Outer Surface FE-BI 바깥영역은 IE Solver 가적용되어 Reflection 이없는이상적조건해석가능 Iterate Surface current on metal block FEM Only Solution Hybrid FEM-IE Solution IE Region FE-BI 15
Single Element Examples Dipole Antenna Ideal Dipole Antenna Gain = 2.15dBi 16
Single Element Examples Patch Antenna Antenna 17
Array Antenna Example 8x8 Patch Antenna Antenna 18
Analysis Time & Memory Elapsed Time Comparison < Single Patch Antenna Case > Used H/W : 2.7GHz CPU with 8cores, 64GB RAM ABC PML FE-BI Adaptive Pass # 9 9 8 Solved Elements 21,554 17,338 15,355 Adaptive Time 00:01:09 00:00:42 00:01:09 Used Memory 765MB 654MB 366MB < 2x8 Array Antenna Case > ABC PML FE-BI Adaptive Pass # 11 11 11 Solved Elements 260,787 269,511 213,308 Adaptive Time 00:12:18 00:13:46 00:23:47 Used Memory 8.2GB 51.3GB 4.0GB < 8x8 Array Antenna Case > ABC PML FE-BI Adaptive Pass # 10 11 11 Solved Elements 1,179,410 1,151,860 1,233,570 Adaptive Time 01:19:59 01:33:04 09:33:02 Used Memory 48.2GB 51.3GB 27.3GB 19
흡수경계조건사용 Guide 지향성단일안테나의경우는 Radiation BC 로도무난함. Omni-Directional 또는 Array 안테나해석에 PML 또는 FE-BI 사용을권장 단, FE-BI 의경우 R18.x 부터모든 HFSS User 가사용가능하지만, Domain Decomposition 사용이필수이므로 HPC 가있어야만동작됨 FE-BI 에대한이해 전기적으로큰문제를해결하기위해 FEM 과 IE 를 Hybrid 로사용하는방식이어서 Domain Decomposition 을사용함. 빠른해석을위한목적보다는한대의 H/W 로해결하기어려운문제를여러대의 PC 로분산처리하는목적 Large Array 와같이 Port 가많아질경우 Mesh 를분할하고다시재조합하는시간이추가되어해석시간이길어질수있음. 그러나 PML 에비해상대적으로 RAM 사용량이줄어들어효율적임. Port 가적을경우전기적으로큰구조를적은 resource 로빠르게해석가능. 20
안테나설계를위한 HFSS Tip #3 Array Synthesis (Estimation to full array) 21
Array Performance Estimation with Single Element < 간략한 Array 효과분석 > Single Antenna(Unit Cell) 의결과만으로 Array를구성하여결과예상 Mutual coupling Effect가반영되지않아정확한예측은어려움 간단하고빠르게초기 Array 구성설계를할수있음 - Array 개수, 배열간격, 배열모양등 22
Finite Array for Large Scale Array < 정확하고빠른 Array 효과분석 > 해석된 Single Antenna 의 Mesh 를복사하여 Array 를정확하면서빠르게해석 전체 mesh 를계산하므로 Mutual coupling Effect 가반영됨 다양한 Array 구성이가능하며, 각 Port 조건도 Post-Processing 으로조정가능 Large Array 인경우 Memory Resource 및해석시간단축가능 HPC 의 Domain Decomposition Method(FA-DDM) 기능으로병렬연산 23
Finite Array Domain Decomposition Method Array 의각 Element 들을 solution domain 으로처리 각 element 의 Mesh 를 Core 별로분산시켜병렬해석 Port 수가많은 large array 에서 DDM 기법을사용하여병렬처리로효율적으로해석 한네트워크에연결된여러대의 Workstation 들을사용할경우 H/W resource 조건을고려하여자동으로최적화하여분산처리 24
Estimation / Finite Array / Explicit Array Single (Master/Slave) RAM : 115MB Adaptive : 53sec Finite Array RAM : 1.28GB Adaptive : 1m54sec Explicit Array RAM : 9.61GB Adaptive : 13m46sec 25
26 전기적으로큰구조해석을위한 HFSS solutions
Electrical Size ANSYS Electromagnetic Solver Portfolio Hybrid Solver and Domain Decomposition SBR+ - Asymptotic, Shooting Bouncing Ray HFSS IE - Method of Moments HFSS - Finite Elements Geometry and Material Complexity 27
HFSS 의 Hybrid Solver Hybrid Solver Finite Element Boundary Integral + IE / PO / SBR+ HFSS R18(2017) 부터별도 HFSS-IE license 없이 Hybrid Solver(FE-BI, IE Region) 사용가능 R18 부터 SBR+ Region 추가 PO Region 및 SBR+ Region 을사용하기위해서는 HFSS-SBR+ option license 필요 HPC Domain Decomposition 26 GHz RAM Elapsed Time PML 259G (DDM) 840min FE-BI 64G 205min FE-BI: 4.1x speedup factor and 75% less RAM 28
Hybrid Solver Example Antenna : FE-BI PCB : IE Region Cover : FE-BI Side View 29
Hybrid Solver Example Radome Effect : 28GHz Array Antenna on Mobile Handset Cover X Cover O 30
Hybrid Solver with Mesh Reuse Hybrid Solver 를이용하여 Mesh 를재사용한빠른 Parametric Sweep 가능 Cover 높이변수 DeltaZ < DeltaZ Parameter Sweep > DeltaZ Adaptive Time Initial Mesh Last Mesh 0mm 00:25:55 12,950 32,238 0.2mm 00:05:32 32,238 32,238 0.4mm 00:06:11 32,238 32,238 Mesh 를재사용하여해석시간단축 31
Installation with Radome in E-Large Scale Automotive Radar Far field Pattern In FREE SPACE Far field Pattern INSTALLED in Facia Installation Analysis with SBR+ 32
33 Adaptive Beamforming
Beamforming in Phased Array Antenna Phased Array 34
Phased Array Antenna System Dynamic Link MIMIC in HFSS 3D Layout Push-Excitations Non-Linear Circuit with RF Option 3D System with HFSS 35
End-to-End System Example SBR+ solver FEM solver Hybrid solver 36
Adaptive Beamforming Savant(SBR+ solver) & Python Script Line of Sight No Line of Sight Phased array tracking beacon antenna PEC plates transitions across line of sight between array and beacon antenna 37
Beam Forming Optimization < Post-Processing Variables > HFSS에서 Post-processing 값에도변수정의가가능하며, 변수조건에따른재해석이필요없이결과를확인할수있습니다. Parametric Sweep, Optimization 활용시빠른시간에확인가능 Port 조건에따른 Far-field 및 Active S-parameter의실시간 Tuning 활용 38
Beam Forming Optimization < Real Time Tuning > Gain Pattern Tuning Slide Bar Active S-parameter 39
Beam Forming Optimization < Far-Field Pattern Optimization> Theta=20deg 일때 Beam Peak 조건최적화 40
Beamforming Area Consideration Far-field Report with Sine Space 구좌표계를 Normalize 된 UV 평면으로표현 -1 < U=sin(θ)cos(φ) < 1-1 < V=sin(θ)sin(φ) < 1 Phased Array 의 Port 조건에따른 far-field pattern 을 sine space 로 export Port 조건에대한경우가많으므로 Script 로자동화 41
Sine Space Example 1x4 Array Case #1 < Gain 6dB 이상영역계산 > Conditions Case #1 Case #2 Total # of cell 31,417 31,417 Case #2 Target # of cell 7,129 4,496 Coverage Area 22.69% 14.31% 42
43 제조공정을고려한시뮬레이션
Coating & Plate Analysis 도금층또는 Radome 의 coating layer 를반영하고해석이필요한경우 3D 모델링대신 Layered Impedance 경계조건으로쉽게해석가능 < 3D Model > < Layered Impedance Surface > 44
Warpage Problems 공정상발생한열또는 Chip 소자에의한발열현상으로 PCB 변형이발생하고이에따른 Antenna 영향도분석 Thermal/Stress/Electromagnetics 가복합된 Multi-Physics 문제 Two-way coupled Two-way coupled EM Fields (HFSS) Thermal (ANSYS Mechanical or Icepak) Stress (ANSYS Mechanical) ANSYS Mechanical 을통해서열응력해석이가능 < 열응력해석에필요사항 > 온도분포 구속조건 재질의열팽창계수 (CTE) 또는탄성계수 < 열응력해석 Output> Temperature distribution Stress distribution Deformation 45
Simple Warpage Condition Analysis Warpage Center Freq. HPBW phi=0 HPBW Phi-90 20um 27.34(Ref.) Ref. Ref. 40um 27.3(-0.15%) 0.03% 0.46% 60um 27.32(-0.07%) 0.43% 0.51% 80um 27.31(-0.11%) 0.42% 0.43% 100um 27.22(-0.07%) 0.24% 0.25% 1x4 Array @ 28GHz 46
Thank You!! Kihyun Kong, Ph.D. Sr. Application Engineer ANSYS Korea e-mail : kihyun.kong@ansys.com 47