HF Antenna Modeling and Construction Wayne Freiert WB2LYL Joe Hood K2YA
Introductions Wayne Freiert - WB2LYL Extra Class Amateur Licensed since 1963 Retired Electrical Engineer Manager Joe Hood K2YA Extra Class Amateur Licensed Since 1955 Retired Electronics and Project Engineer
The Light Beam Team Wayne Freiert - WB2LYL Founder CEO Brian Bieger KC9HEK Marketing Finance Joe Hood K2YA Engineering and Technical Other folks???
Background Developed Concept for the Compact and Stealthy Light Beam Antenna Needed an Antenna having Gain and Directivity Needed a Compact Yet Efficient Antenna Design. Needed a Stealthy Antenna Design with Low Visual Impact. Wanted to Minimize Development Cost Answer => Antenna Modeling Software also Want to Share Experience Knowledge
Content Introduction to Antenna Modeling Software High Level Explanation of How it Works Describe Basic Inputs Required Review Several Examples Review Antenna Construction Suggestions Questions (and maybe) Some Answers
Antenna Modeling Important Considerations Polarity Radiation Pattern Gain Impedance Antenna Installation Location Ground characteristics distance to the radio Height mounting structure Size, weight visual impact
Modeling Software Computer Technology NEC2GO Where to get it: www.nec2go.com How it Works Inputs Required Uses Cartesian Coordinate (X,Y,Z axis) Input System Describes Physical Antenna User Can View Described Antenna Also Conductor Sizes, Types and Insulation Selectable Ground Characteristics
Modeling Analysis Segments must be increased until results converge Available Results: Impedance versus Frequency (R, +/- j X) Radiation Pattern (Gain, Front to back, etc.) SWR versus Frequency % Efficiency versus Frequency Characteristic (Gain, SWR, etc.) versus Variables of (spacing, height etc.) Optimization Requires some technique: Patience and a High Speed Computer are required Using good scientific methods Keep copious notes
Examples Antennas: Simple Dipole Folded Dipole 3 Wire Folded Dipole Bent Dipole Open Loop dipole Two Element
Simple Dipole
Simple Dipole
Simple Dipole Input File 15 Meter Dipole Antenna, Freq: 21.3 MHz, Units: Inches, AST len = 262 ;length of the driven element Hgt = 360 ;height above ground Source: Center 1 0, -(len/2), Hgt 0, (len/2), Hgt #12 ;Comments:
Simple Dipole Length = 21.83 feet Z0 = 64.3+j4.8 ohms SWR = 1.3:1 (50 Ohm System) Gain = 7.69 dbi (@ 30ft above ground) F/B = 0 db Total Loss = 0.03dB
2 Wire Folded Dipole
2 Wire Folded Dipole Length = 21.83 feet Z0 = 259.1+j21.9 SWR = 5.22:1 (50 ohm) Gain = 7.72 dbi F/B = 0 db Total Loss = 0.02dB
Dipole Antennas Dipole Length = 21.83 feet Z0 = 64.3+j4.8 ohms SWR = 1.3:1 (50 ohm) Gain = 7.69 dbi F/B = 0 db Total Loss = 0.03dB Folded Dipole Length = 21.83 feet Z0 = 259.1+j21.9 SWR = 5.22:1 (50 ohm) Gain = 7.72 dbi F/B = 0 db Total Loss = 0.02dB
Dipole Antennas 3 Wire Folded Dipole Length = 21.8 feet Z0 = 524.6+j41.1 ohms SWR = 10.56:1 (50 ohm) Gain = 8.07 dbi F/B = 0 db Total Loss = 0.02 db Bent 3 Wire Folded Dipole Length per side = 7.6 feet Z0 = 156.7+j7.1 ohms SWR = 3.14:1 (50 ohm) Gain = 6.77 dbi F/B = 0 db Total Loss = 0.03 db
Light Beam Antenna Open Loop 3 Wire Dipole Length per side = 6.3 feet Z0 = 92.4-j14.1 ohms SWR = 1.91:1 (50 ohm) Gain = 6.27 dbi F/B = 0 db Total Loss = 0.06 db Antenna Length per side = 6.3 feet Z0 = 40.5-j91.4 ohms SWR = 6.01:1 (50 ohm) Gain = 10.42 dbi F/B = 29.07 db Total Loss = 0.25 db
Light Beam Antenna Azimuth Elevation At 30 feet above ground
Comparisons Dipole Length = 21.8 feet Z0 = 64.3+j4.8 ohms SWR = 1.3:1 (50 ohm) Gain = 7.69 dbi F/B = 0 db Total Loss = 0.03dB Folded Dipole Length = 21.8 feet Z0 = 259.1+j21.9 ohms SWR = 5.22:1 (50 ohm) Gain = 7.72 dbi F/B = 0 db Total Loss = 0.02dB 3-Wire Folded Dipole Length = 21.8 feet Z0 = 524.6+j41.1 ohms SWR = 10.56:1 (50 ohm) Gain = 8.07 dbi F/B = 0 db Total Loss = 0.02 db Note: Z0 = R0+/-jX Note that R0 increases as the number of wires increases. R ~ = R*(N)2 where N = the number of wires (for certain conditions). Gain Increases - but not much
Bent Folded Dipole Width = 7.6 feet Z0 = 156.7+j7.1ohms SWR = 3.14:1 Gain = 6.77 dbi F/B = 0 db Total Loss = 0.03 db Note: Comparisons Open Loop Folded Dipole Width = 6.3 feet Z0 = 92.4-j14.1 ohms SWR = 1.91:1 Gain = 6.27 dbi F/B = 0 db Total Loss = 0.06 db Antenna Width = 6.3 feet Z0 = 40.5-j91.4 ohms SWR = 6.01:1 Gain = 10.42 dbi F/B = 29.07 db Total Loss = 0.25 db R0 decreases as you bend the elements. Gain Decreases - but not much Gain and F/B increase dramatically when you add a parasitic element. 0.25dB loss = 5.56% wire loss. Antenna Efficiency = 94.4%
Important Note has filed a Patent Application for the antenna design described today. The patent is pending. You have permission to build your own similar antenna for your personal, non-commercial, use and enjoyment.
Construction Safety Cutting wire to precise lengths Terminating wires Working with Aluminum Tubing - cutting and drilling. Working with Plastics Working with Fiberglass Feed-line choices
Useful Tools
Construction Baluns Coaxial Chokes Feed-line Transformers L-Networks Other matching techniques Gamma Match T-Match Beta Match Delta Match stubs, etc.
Construction A list of materials and tools suppliers: McMaster Carr Granger Industrial Supply Victor Machinery Exchange DX Engineering Max-Gain Systems Georgia Copper Professional Plastics
Light Beam-Plus Antenna
Light Beam-Plus Antenna
Questions??