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A 7el 12.5 Ohm 50MHz Optimised Wideband Low impedance (OWL) Yagi

Premium commercial versions of this antenna at Innovantennas

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 in the CONSTRUCTION menu above.

Do not look at the gain figure of this antenna and compare with other 7 element 50MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With 12.7dBi and a boom less than 7.9M long, this antenna will be a winner for field days and the rural Ham radio operator.

PLEASE NOTE:

  • 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

Performance UK/USA Version

Forward Gain:                           12.69dBi at 50.250MHz

Front to Back Ratio:              24.01dBi at 50.250MHz

Peak Gain:                                 12.74dBi

Peak F/B:                                24.32dB

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                                   1.513                                               12.7mm 1/2 inch Diameter tube

DE                       .173                               1.460                                               12.7mm  1/2 inch tube

D1                       .575                               1.413                                              12.7mm 1/2 inch Diameter tube

D2                     1.880                               1.365                                               12.7mm 1/2 inch Diameter tube

D3                     3.791                               1.332                                               12.7mm 1/2 inch Diameter tube

D4                     5.894                               1.315                                               12.7mm 1/2 inch Diameter tube

D5                     7.890                               1.296                                               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                                   1.5105                                             12mm Diameter tube or solid rod

DE                       .173                               1.460                                              12mm Diameter tube or solid rod

D1                       .570                               1.4135                                             12mm Diameter tube or solid ro

D2                     1.880                               1.3645                                             12mm Diameter tube or solid rod

D3                     3.791                               1.3325                                             12mm Diameter tube or solid rod

D4                     5.891                               1.3175                                             12mm Diameter tube or solid rod

D5                     7.890                               1.294                                               12mm Diameter tube or solid rod

Fantastic Azimuth plot of this 7el 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