Portable HF Antennas. Think Like A Backpacker. George - KJ6VU

Transcription

1 Portable HF Antennas Think Like A Backpacker George - KJ6VU

2 WWW. HAMRADIO360.COM WWW. PACKTENNA.COM PODCAST

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4 My Personal Goals Operate more HF Get out and hike more Improve my CW skills Build some cool stuff Obsess over a new project

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8 Popular Portable HF Antennas

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11 Just Throw A Wire Up In A Tree

12 Fiberglass Mast

13 1:1 Feed Point Balun Vertical wire element jack Holes for S-Clips - Antenna wire strain relief - Mounting Mounting holes for mini-bungee cords Zip-tie holes to mount toroids Coax connector Horizontal or Vee wire element jacks

14 Feed Points and Chokes 1:1 Balun Feedpoint 9:1 UNUN Feedpoint In-LineCurrent Choke Inverted Vee Ground Plane Dipole End-Fed Wire Any Hi-Z Antenna End-Fed Wire

15 Think Like a Backpacker 1. Weigh your stuff - Ounces add up to pounds. 2. Trim the fat: leave the kitchen sink at home. 3. Plan your trip: limit your contingencies. 4. Take the lightest possible item to do the job. 5. Simplify: take items that serve multiple functions. 6. Don t just take a bunch of stuff: build a system. 7. Get back to the basics - don't over complicate things. Backpacking Light 101 By Ryan Jordan "Seven Steps to Enlightenment

16 Next Project even smaller The MINI 5-1/2

17 ELECTRICAL DESIGN

18 Portable HF Antenna Challenges Needs to be big: 16 to 66 (20m to 80m) Needs some sort of support Needs to be light weight Needs to be compact Answer Wire + Mast (or tree)

19 OK, But What???!!??? What kind of antenna design? What materials? What bands?

20 Wire Antenna Basics X X X Dipole Inverted Vee Ground Plane End-Fed Random Wire End-Fed Half Wave

21 Center Fed Half Wave Dipole ½ wavelength 72 Ohms

22 Off Center Fed Half Wave Dipole 200 Ohms ½ wavelength

23 End Fed Half Wave 4,000 Ohms ½ wavelength

24 Two Common Wire Antennas End Fed Random Wire with a 9:1 UNUN End Fed Half Wave with 50:1 UNUN 1935

25 9:1 UNUN The turns ratio is 3:1 for a transformation of 9:1. The impedance is the square of the turns ratio (Z=T^2)

26 50:1 7:1 Turns = 49:1 Impedance 2450 Ohms : 50 Ohms Z = T 2 Impedance = Turns Ratio Squared

27 MECHANICAL DESIGN

28 Design Goals Combine Wire Winder + 9:1 + Wire Make it smaller

29 Make It Small 5-1/2

30 PT Mini PCB

31 Same PCB Different Torroids 50:1 UNUN 9:1 UNUN

32 50:1 Toroid Core A/C wire length = 24 C Each time the wire passes through the core it is 1 turn 14 turns C B A/B wire length = 6 B A 2 turns bifilar winding A

33 9:1 Toroid Core C Each time the wire passes through the core it is 1 turn B A A

34 FIELD TESTING

35 20m End Fed Half Wave Dimensions 50:1 UNUN 31 3

36 20m End Fed ½ Wave

37 40m & 20m End Fed Half Wave Dimensions :1 UNUN 51 turns #24 on 1 OD PVC

38 20m/40m End Fed ½ Wave Coil

39 Use S-Clips and Banana Connector To Customize Your Setup :1 UNUN turns #24 on 1 OD PVC 51 turns #24 on 1 OD PVC

40 20m/40m End Fed ½ Wave

41 End Fed All Band Random Wire Dimensions 9:1 UNUN 29 TUNER Length = Not a ¼ wavelength or harmonic on any band Good choices:

42 ½ Wave counterpoise

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44 Wire Wrapping Wrap the wire using a figure 8 pattern. Wrap 20 (½ the wire) on one side then 20 (half the wire) on the other side.

45 Thank You