Fan Dipole 40/20/6m

Base

Each band has its own resonant dipole wire pare.

To feed the balanced dipole from 50Ω coax a Balun is needed. I use a D-Original BU-55 balun for this. Frequency range 3 to 75 MHz. Impedance 50 Ω. Ratio: 1:1. Maximum power 500 Watt PEP.

I build this antenna to have a reference antenna for 20 and 40m.

Balun

BU-55 D-Original
BU-55 D-Original

Wire spacing

Placed as a inverted-V every added wire makes a sharer angle at the feed point. 
Most Fan (parallel) antennas are made with the longest wire (lowest band) at the top. Highest band at the bottom.

For wind stability I changed the order and placed the 6m band dipole in the middle. Not sure what this does for radiation angle.

As I use flexible spacers the bottom wire needs a little tension. This is accomplished by en extra non metal wire from the end of the bottom wire to the top wire.. This also increases wind stability.
I think non-flexible spacers my be a better solution...

BU-55 wire spacing
BU-55 wire spacing
Fan antenna for 6/20/40m
Fan dipole antenna for 40/20/6m

Choke balun

As the antenna is hoisted, a ground connection near the feed point with the mast can't be made.

To reduce feed-line radiation a choke balun or ferrite core can be placed near the feed point. For me three ferrite chokes did the job.

Extension

As long as the band is in the range of the balun, any band (dipole) can be added.

Tuning a band may effect other bands. So be careful and cut with care. Measure all bands after every adjustment.

Fan dipole backyard view
Fan dipole backyard view

Measuraments SWR & impedance

40m

Fan dipole 40m SWRFan dipole 40m SmithFan dipole 40m Z

20m

Fan dipole 20m SWRFan dipole 20m SmithFan dipole 20m Z

6m

Fan dipole 6m SWRFan dipole 6m SmithFan dipole 6m Z.png

Editors remark

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