80 m antenna

• Full size• Limited space• Omnidirectional• Low noise• Effective• Cheap

Feedpoint 1

• Balun balance the antenna, so that the dipole radiate even on the two legs

• Veldefinet radiation• Less BCI tendency

Feedpoint 2

• Lexan sheet • 2 toroids w. 3 vdg.• Impregnated w.

linenoil• Baked at 70 dg C for

2days• Holding cable• Holding antenna wire• Feedcabel RG58

Feedpoint 3

• 3 windings pr core• Each gives 500 Ohm• 2 in serie gives 1000

Ohm• Wire ø 1,25 mm• Wire and cabel

solderet• Silikoneprotected

Feed cable

• For each 2,5 m on feeder ferritetubes are placed

• Each tube gives 100 Ohm• Feeder do not resonate, or

disturb radiation diagram• BCI advantage• ½ wavelength X 0,66

Antenna mast

• 6 m flagpole• Wooden pole 3,6 m• Totalheigth 8 m• Supporting wire

Endpoints of antenna

• Endpoints in trees• Springs in stainless

steel to eleminate the movement of the trees

• 8/6 m heights• 105 grader

Calculation of balun

• Z=AL x N x N• Example: J-42915 –

TC, at 4 Mhz AL = 30• 3 turns gives 30 x 9 =

270 Ohm

Groundplane

• Wires on ground• Internally connected• Not connected to earth• Less loss to ground• Less noise from mains

supply• More radiated power

Horisontal radiation diagram

• 105 dg horisontal wires

• Almost omnidirectional

• Ideel to localtrafic• Working fine up to

2000 Km

Vertikal radiation diagram 1

• Antenna height means all for the vertical radiation

Vertikal radiation diagram 2

• Big heights are not always an advantage!!

Bandwith

• 3500 KHz: 136 Ohm• 3600 Khz: 78 Ohm• 3700 Khz: 50 Ohm• 3800 Khz: 80 Ohm