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 (#14 AWG), (2) insulators, center connector (ladder lock) 450 ohm window line, 4:1 balun and a tuner.

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 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 of TX power and found that every band tuned easily wth an LDG AT-100PRO autotuner.  We were able to make numerous contacts during the brief test including contacts with Saudia Arabia, United Arab Emirates, Crotia, Columbia, and Paraguay.

Caution: Keep the window 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 included below.  Predicted transmission line (TL) efficiency (% power delivered to antenna) was calculated with VK10D’s RF Transmission Line Loss Calculator using EZNEC SWR values.

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

ocf-eznec-models

80 meter band

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actual 80 meter SWR curve


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Predicted 80 meter TL efficiency
Frequency (MHz) Efficiency (%)
3.50 94.92
3.75 97.57
4.00 98.46
 

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40 meter band

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actual 40 meter SWR curve

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Predicted 40 meter TL Efficiency
Frequency (MHz) Efficiency (%)
7.00 97.62
7.15 98.14
7.30 98.26
 
 

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20 meter band

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actual 20 meter SWR curve


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Predicted 20 meter TL efficiency
Frequency (MHz) Efficiency (%)
14.00 92.45
14.17 93.71
14.35 94.81
 

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17 meter band

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actual 17 meter SWR curve

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Predicted 17 meter TL efficiency
Frequency (MHz) Efficiency (%)
18.068 94.65
18.113 95.06
18.168 95.54
 
15 meter band

imageactual 15 meter SWR curve

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Predicted 15 meter TL efficiency
Frequency (MHz) Efficiency (%)
21.000 91.97
21.225 92.78
21.450 93.94
 
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12 meter band
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actual 12 meter SWR curve
 
Predicted 12 meter TL efficiency
Frequency (MHz) Efficiency (%)
24.89 92.07
24.93 92.28
24.99 93.94

 

image10 meter band

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actual 10 meter SWR curve

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Predicted 10 meter TL efficiency
Frequency (MHz) Efficiency (%)
28.00 90.75
28.85 89.54
29.70 88.69
 
 
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6 meter band

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actual 6 meter SWR curve