HF Antenna Modeling and Construction

Transcription

1 HF Antenna Modeling and Construction Wayne Freiert WB2LYL Joe Hood K2YA

2 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

3 The Light Beam Team Wayne Freiert - WB2LYL Founder CEO Brian Bieger KC9HEK Marketing Finance Joe Hood K2YA Engineering and Technical Other folks???

4 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

5 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

6 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

7 Modeling Software Computer Technology NEC2GO Where to get it: 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

8 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

9 Examples Antennas: Simple Dipole Folded Dipole 3 Wire Folded Dipole Bent Dipole Open Loop dipole Two Element

10 Simple Dipole

11 Simple Dipole

12 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:

13 Simple Dipole Length = 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

14 2 Wire Folded Dipole

15 2 Wire Folded Dipole Length = feet Z0 = j21.9 SWR = 5.22:1 (50 ohm) Gain = 7.72 dbi F/B = 0 db Total Loss = 0.02dB

16 Dipole Antennas Dipole Length = 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 = feet Z0 = j21.9 SWR = 5.22:1 (50 ohm) Gain = 7.72 dbi F/B = 0 db Total Loss = 0.02dB

17 Dipole Antennas 3 Wire Folded Dipole Length = 21.8 feet Z0 = 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 = j7.1 ohms SWR = 3.14:1 (50 ohm) Gain = 6.77 dbi F/B = 0 db Total Loss = 0.03 db

18 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 = dbi F/B = db Total Loss = 0.25 db

19 Light Beam Antenna Azimuth Elevation At 30 feet above ground

20 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 = 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 = 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

21 Bent Folded Dipole Width = 7.6 feet Z0 = 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 = dbi F/B = 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%

22 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.

23 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

24 Useful Tools

25 Construction Baluns Coaxial Chokes Feed-line Transformers L-Networks Other matching techniques Gamma Match T-Match Beta Match Delta Match stubs, etc.

26 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

27 Light Beam-Plus Antenna

28 Light Beam-Plus Antenna

29 Questions??