Transcript Document
Antenna Design Tools VE3KL • Antenna simulation tools based on NEC Fortran Program Eznec 4NEC2 (free) including optimizer and tuner design • Transmission Line Utility (TLDetails, Dan Maguire, AC6LA) • Antenna Tuner Utility (included in 4NEC2) • Specialized C#, C++, VB programs to drive EZNEC/4NEC2 • Measurement Tools and Software : AIM4170 vector meter + Zplots(AC6LA) 7/17/2015 David Conn VE3KL 1 Outline • My Antenna Design Process • 4nec2 Overview..Analysis, Optimization, Utilities • Design Example …..40/17 metre fan dipole • Future Trends • Demo of 4NEC2 or AIM4170 Analyzer 7/17/2015 David Conn VE3KL 2 Antenna System Simulate/build/test Antenna Transmission Line Zo, velocity, length losses Use TLDetails to select Tuner Discrete or Stubs Optional : use if SWR >1.5 Transmitter Power and Frequency David Conn VE3KL 3 My Design Process Idea ? 4nec2 Simulator Optimizer Transmission Line Analysis (TLDetails) Tuner Design 4NEC2 Matching Utility Build Measure Vector Z meter Aim 4170 ….. File Transfer .csv Capture Data for plotting Zplots Software Design Review OK ? Start Over? David Conn VE3KL 4 4nec2 ArieVoors • • • • • • • A free full featured antenna simulator Uses the nec FORTRAN kernel Several input editors Built-in 3D graphics Excellent help file Many standard antennas….helix etc. First free simulator to contain an optimizer 7/17/2015 David Conn VE3KL 5 Spherical Coordinate System Z θ Rx Antenna Elevation angle = 90 - θ Tx Antenna Y φ XY Horizontal Plane Z Vertical axis X φ is the horizontal azimuth angle Θ is the angle measured from vertical 7/17/2015 David Conn VE3KL 6 Method of Moments • A discrete numerical method • Divide wires into many segments • 25 segments per wavelength 7/17/2015 David Conn VE3KL 7 Use built-in editor to the Define Antenna Geometry 4nec2 Simulation Analyze Gain,SWR… Optimize (Tune) Use TL Details to select Transmission line Use Matching Utility to Design Tuner if Needed David Conn VE3KL 8 The Big Gun (Optimization) Optimize (Tune) a 2 metre dipole to 6 metres Adjust reactance to zero Vary Length Results L= 2.8 metres Xin = -0.13 Ohms 7/17/2015 David Conn VE3KL 9 4NEC2 Far Field Traditional Plot Several Views • Vertical, Horizontal, Total • Circular Polarization RHC, LHC, Total 7/17/2015 David Conn VE3KL 10 3D VE3XK 50 MHz Stack 50 MHz OMNI Source Side Along X Axis Right Hand Circular Polarization Shown All Graphs are dynamic 7/17/2015 David Conn VE3KL 11 4NEC2 3D Near Field 7/17/2015 David Conn VE3KL 12 4NEC2 Advanced Far Field Map θ High Gain φ 7/17/2015 David Conn VE3KL 13 Spherical Coordinate System Z θ Rx Antenna Elevation angle = 90 - θ Tx Antenna Y φ XY Horizontal Plane Z Vertical axis X φ is the horizontal azimuth angle Θ is the angle measured from vertical 7/17/2015 David Conn VE3KL 14 Examples “Simple” 2m Dipole Free Space -L/2 L/2 X Axis Total Gain Theta = 75 degrees PHI = 311 degrees 7/17/2015 David Conn VE3KL 15 Simple 2m Dipole .. Horizontal Plane -L/2 L/2 X Axis Horizontal Plane BLUE :Vertical E Field RED: Horizontal E Field Green: Total Field Theta = 45 degrees (Is it OK to say that a dipole is Horizontally Polarized? No!) Receives Power Line Noise off the end (Vertically Polarized) 7/17/2015 David Conn VE3KL 16 4NEC2 Several Views of Frequency Response David Conn VE3KL 17 4NEC2 Smith Chart David Conn VE3KL 18 A Design Example Two Element Fan Dipole 40/17 metres • • • • • • Wire Lengths? Tuner needed? Frequency Response? Gain and direction of radiation? Mounted between two towers (North South) Simulate/Build/Test 7/17/2015 David Conn VE3KL 19 Two Element Fan Dipole Four Wires Connected to a Transmission Line L1 (1/4 Lambda) 40 metre top section 30 degrees 17 metre bottom section (Inverted V) L2 (1/4 Lambda) Height RG8-X Cable (Length, Losses, Zin) Tuner Lossy Ground 7/17/2015 Transmitter David Conn VE3KL 20 Two Element Fan Dipole 40 Metre Gain Pattern……broadside radiation 7/17/2015 David Conn VE3KL 21 Two Element Fan Dipole 17 Metre Gain Pattern……45 degree lobes 7/17/2015 David Conn VE3KL 22 Two Element Fan Dipole Frequency Response ..SWR around 1.5 Tuner might be useful Very High SWR ??? Good Candidate for an auto-tuner David Conn VE3KL 23 Two Element Fan Dipole Frequency Response…… Impedance Z= 28.5+j2 Ohms @ 18 MHz 7/17/2015 David Conn VE3KL 24 TLDetails to select the Transmission Line Length needed = 15 Metres Zin = 40 + j 20 David Conn VE3KL 25 Matching (4nec2 Utility) 18 MHz No need for Xs David Conn VE3KL 26 Measurements Antenna or other DUT Aim 4170 Vector Z Meter Complete Data Set Generated .csv Import Data to Zplots or Excel or Data Base (SQLITE) Plotting or Further Computing E.g.. Calculate Cable Losses AIM 4170 Vector Impedance Meter Connected to Computer via Serial Port 27 Fan Dipole Measurements AIM4170 & Zplots Measured Simulated David Conn VE3KL 28 The Future • Much more software integration needed link measurement tools to all software include data base output for all software use Excel and SQLite data bases standard data base file format • Models, especially ground types need improvement • Much more work on optimization • Electrical design to mechanical drawing needed for Microwave Antennas 2010 Antenna design tools similar to Silicon IC design in its infancy Summary • Antenna/Simulation Tools are well developed • See VE3KL’s articles in TCA for more details • Presentation posted on ve3kl.com Web Site VY 73 Dave VE3KL