Memoirs of DXCC

1. Memoirs of DXCC Joe Horanzy AA3JH April 4th, 2013 K3DN Presentation

2. Agenda Awards Impedance Measuring Equipment Picking the Antenna Antenna components with construction tips and theory Putting it all together Multiband Getting more gain Simulation tools Vertical Moxon Future plans

3. Awards

4. 10 meter progress Open to all license classes

5. Impedance Z = R + jX Where R = natural antenna and grd loss resistance X = total antenna reactance combination of capacitance and inductance Reactance (X) is your enemy. Why? A reactive component alternately absorbs energy from the circuit and then returns energy to the circuit. A pure reactance will not dissipate any power.

6. Impedance You can’t go by just impedance (Z) alone. A Z of 50 of resistance vs. a Z of 50 reactance is very different. A Z of 50 of pure resistance = SWR 1:1 A Z of 50 of reactance = SWR >20:1 ! A Z of 100 of pure resistance = SWR 2:1 A Z of 100 of reactance = SWR >20:1 !

7. Impedance “So I have residual reactance, so what? I’ll tune it out with my trusty antenna tuner in the shack.” #1 Remove all reactance at the antenna. Matching at the transceiver only satisfies the connection between the transceiver and the tuner. Loss in the cable dramatically increases

8. Impedance

9. Measuring Equipment

10. Picking the antenna Main Object: Get on HF to communicate around the world (DX) with an antenna that is: • Simple • Low maintenance • Ease of construction • Readily available components • Stealth • Low cost • But very efficient and effective.

11. The Vertical Antenna Few components, low cost. Easy to hide. Easy to make multiband. Has low take off angle, great for DX DX is not line of sight. Polarization doesn’t matter. Vertical dipoles: don’t need ground radials but is ½ l and end fed requires matching. ¼ wave vertical: only ¼ l high (half the V/D height), no balun required, but requires ground radials.

12. The ¼ Wave Vertical They get a bad name because many don’t radiate from improper installation from: • Ineffective ground plane / counterpoise • Residual reactance, not resonating. • Improper trap design causing excess loss. Anytime you move from the basic antenna, there will always be compromises either through power loss and/or bandwidth limitations.

13. The ¼ Wave Vertical

14. The ¼ Wave Vertical Single Band • How high: *235/ Freq (Mhz) example: for 14.1 Mhz 20 meter band 235 / 14.1 = 16.7 feet. *235 is from: 300 M meter/sec (speed of light) X 95% (speed of light slows down in wire) /4 (1/4 wave) X 3.3 ft/m (convert to ft)

15. The ¼ Wave Vertical Ground system

16. 2. How many ground radials why? • Soil has high resistance. • To reduce ground resistance as much as possible. • Any power that is dissipated in the soil weakens the signal. As they say: heating up the worms From Arrl Antenna handbook

17. Ground loss Rr: Antenna’s natural radiations resistance: is the virtual resistance in transferring the energy to produce the radio wave. For ¼ wave vertical antennas, it’s about 36 ohms. (note: SWR 1:4) Rg: Ground loss resistance. Rtotal = Rr + RgZ = Rtotal+ jX Antenna efficiency (%) = (Rr / Rtotal ) x 100 For example: say ground resistance is 14 ohm, then Rtotal = 36 + 14 = 50 ohms, great SWR but… Efficiency = 36/50 x 100 = 72 percent If 100 W is transmitted only 72 watts is being radiated. xmit Rr: Radiated resistance Rg: Ground resistance From Arrl Antenna handbook

18. Ground radials

19. The ¼ Wave Vertical 2. Ground radials length: .25 l or greater. For multiband, use random lengths. 3. Wire size: 12 or 14 AWG 4: Type: Stranded for vertical Solid for ground radials 5: Insulated: Doesn’t matter.

20. COMPONENTS OR

21. Putting it all together Bungee cord 20M trap

22. Ground Connection

23. Ground Connection Close up

24. Multiband Vertical Resonate Traps:

25. Trap: Inductor/ HV Cap

26. Multiband Vertical Another approach Fan Vertical

28. Contacts made with home brew fan vertical antenna (40 to 10 meter) No amplifier.

29. Summary Cancel out all reactance at the antenna. Install best ground radials as possibleto keep ground resistance low as possible. Keep all component loss in the system to a minimal. Use good coax, RG213 or better, and ensure all connections are soldered correctly (beware of HRO).

30. Gain Dbi : Gain measured in relation to an isotropic radiator, an imaginary antenna in freespace. Dbd : is a reference to a dipole antenna in free space and is simply Dbi - 2.15 Dipole in freespace can have 2.15 Dbi gain or 0 Dbd. From Arrl Antenna handbook

31. Vertical ¼ wave vs. Horizontal Dipole Vertical Horizontal Azimuth Pattern: Antenna radiation pattern viewed from above.

32. Vertical ¼ wave vs. Horizontal Dipole Horizontal Vertical Elevation Pattern: Angle of maximum radiation in relation to the ground. Lower the better for DX.

33. Height above ground of a Horizontal antenna to be effective “Sky shooter” Comparable to vertical Lowers angle even more Bad for DX More gain than vertical Creates multiple lobes Would require rotator

34. How to get gain out of my vertical? Yagi style but vertical?

35. The Moxon Variation of the Yagi Compact than Yagi Equivalent gain of a YagiHigh front back ratio

36. The Moxon http://www.moxonantennaproject.com/design.htm

37. Free simulation software http://www.qsl.net/4nec2/

38. Free simulation software

39. Vertical Moxon Simulated results

40. Horizontal Moxon Simulated results

41. The Vertical Moxon

42. End Fed Matching Network • Pick permeability • too low: too much wire • too high: more loss • Self resonate secondary winding in band to prevent additional reactance (16T) • Measure Z at antenna input (2K) • Calculate turns ratio: • Calculate primary winding: 16/6.3 = 2.5 turns • Short secondary, measure primary Z, note reactance. • To cancel out the inductive reactance, put series capacitor with same reactance in series with the input of the primary.

43. The Vertical Moxon

44. Future plans Hex Beam

45. Future plans Hex Beam

46. Future plans Hex Beam

47. Thank you very much DE AA3JH