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A 9el 12.5 Ohm 50MHz Optimised Wideband Low impedance (OWL) Yagi

Premium commercial versions of this antenna at Innovantennas


Revised  February 2010


The OWL by G0KSC provides the benefits of both OWA (Optimised wideband Array) 50 Ohm antennas with those of traditional low impedance antennas. More information on the OWL can be found here

Visit HERE to learn how to make the OWL Match/Balun

Do not look at the gain figure of this antenna and compare with other 9 element 50MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With almost 14.05dBi and a boom less than 12.5M long, this antenna will be a winner for field days and the rural Ham radio operator.


  • Special attention should be taken in ensuring the element spacing and sizes are absolutley correct upon a 12.5 Ohm Yagi
  • If SWR is not perfect, D1 may also need to be adjusted. An analyser is reccomended for use when finalising 12.5 Ohm OWL Yagis
  • Visit 'Making the OWL Match' for more information on the recommended matching methods
  • Please add 2mm to each element to allow for insulator correction if using G0KSC insulators. Other insulators may require different correction Email me for details

The 8el OWL installed at ZL1RS

Performance UK/USA Version

Forward Gain:                           14.05dBi at 50.250MHz

Front to Back Ratio:              22.67dBi at 50.250MHz

Peak Gain:                                 14.07dBi

Peak F/B:                                22.73dB

Bandwidth:                               500KHZ below 1.2:1


Build Dimensions for UK/USA Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   1.491                                              12.7mm 1/2 inch Diameter tube

DE                       .270                               1.448                                               12.7mm  1/2 inch tube

D1                       .769                               1.411                                              12.7mm 1/2 inch Diameter tube

D2                     1.908                               1.375                                               12.7mm 1/2 inch Diameter tube

D3                     3.687                               1.3425                                             12.7mm 1/2 inch Diameter tube

D4                     5.790                               1.3215                                             12.7mm 1/2 inch Diameter tube

D5                     8.029                               1.297                                               12.7mm 1/2 inch Diameter tube

D6                     10.446                              1.2845                                            12.7mm 1/2 inch Diameter tube

D7                     12.438                              1.291                                              12.7mm 1/2 inch Diameter tube


Build Dimensions for European Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   1.492                                              12mm Diameter tube

DE                       .270                               1.449                                              12mm Diameter tube

D1                       .769                               1.412                                              12mm Diameter tube

D2                     1.908                               1.376                                               12mm Diameter tube

D3                     3.687                               1.3435                                             12mm Diameter tube

D4                     5.790                               1.3225                                             12mm Diameter tube

D5                     8.029                               1.298                                               12mm Diameter tube

D6                     10.446                             1.2855                                             12mm Diameter tube

D7                     12.438                             1.292                                               12mm Diameter tube



Fantastic Azimuth plot of this 9el 50MHz OWL Yagi





The Elevation plot is really clean too. A quiet antenna compared with most!





This SWR plot is taken with the Coaxial stub embedded within the EZNEC model Ever seen a 12.5 Ohm antenna like this one before? Watch how many now appear on the Internet but remember where you saw them first!



The G0KSC OWL element layout. Note the close spacing of the first 3 elements which give the OWL its extra gain and wide bandwidth.

As always, or if you have difficulty tuning, please Email me!


Justin G0KSC


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