Multi-Band OCF-dipole Antenna

Looking for a good multi-band wire antenna that covers 80, 40, 20, 17, 15, 12, 10, and 6 meters?  You will like this one.  It’s cheap and easy to build.  All you need is 133’ of wire, (2) insulators, center connector (ladder lock), 450 ohm ladder line, good quality 4:1 current balun and an unbalanced tuner.  A balanced tuner can be used if you have one.

NOTE: Due to the variances in impedance presented by the antenna, an autotuner is recommended.

KI4PMI and I built one of these antennas and analyzed it on the bands listed above.  We like to compare the EZNEC model SWR predictions to the actual SWR measurements made with an AIM-4170C antenna analyzer.  The SWR comparisons for each band are included below.  We tested the antenna using 90 watts and found that every band tuned easily wth an LDG AT-100PRO autotuner.  We were able to make numerous SSB phone contacts during a brief test including contacts with Saudia Arabia, United Arab Emirates, Crotia, Columbia, and Paraguay.

Caution: Keep the ladder line away from trees, structures, metal objects, and off the ground.

ocf-dipole-diagram

The EZNEC model predictions for the 80, 40, 20, 17, 15, 12, 10, and 6 meter bands are displayed below.  The measured values can be viewed by clicking the links under the predicted displays.

EZNEC models for each band are available in a zipped file for download at the link below.

ocf-eznec-models

NOTE:  The characteristic impedance and velocity factor (VF) of ladder line made by different manufacturers can vary significantly.  These variations are caused by the material used, insulation, distance between parallel wires, etc.  The characteristic impedance of 450 ohm ladder line can vary from 360 ohms to around 405 ohms.  The velocity factor can vary from around .89 to .93.

predicted 80 meter band SWR80m-swrmeasured 80 meter SWR

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predicted 80 meter radiation pattern

80m-radiationpredicted 40 meter band SWR

40m-swrmeasured 40 meter SWR

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40 meter band predicted radiation pattern

40m-radiation20 meter band predicted SWR

20m-swrmeasured 20 meter SWR curve

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20 meter band predicted radiation pattern20m-radiation
 17 meter band predicted SWR

17m-swrmeasured 17 meter SWR curve

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17 meter band predicted radiation pattern
17m-radiation
15 meter band predicted SWR
15m-swrmeasured 15 meter SWR curve

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predicted 15 meter band radiation pattern

15m-radiation12 meter band predicted SWR

12m-swr
measured 12 meter SWR curve
12 meter band predicted radiation pattern 12m-radiation10 meter band predicted SWR

10m-swrmeasured 10 meter SWR curve

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 10 meter band predicted radiation pattern
10m-radiation6 meter band predicted SWR

6m-swrmeasured 6 meter SWR curve

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 6 meter band predicted radiation pattern
 6m-radiation

1 Response to “Multi-Band OCF-dipole Antenna”


  • Very helpful information! I’m working around HOA restrictions and need to move the feedpoint of my extended double Zepp closer to the house; 50′ may be perfect. I may try using 300 Ohm TV twinlead to minimize visibility and run that into the shack and my Johnson Matchbox.

    Thanks,

    Jim
    KL7JBB

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