A 11el 12.5 Ohm 50MHz Optimised Wideband Low impedance (OWL) Yagi

Revised  February 2010

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 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 11 element 50MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With almost 15.16dBi and a boom less than 16.6M 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 for thru-boom and element insulators add 3mm

The Force12 17.9m long version of this antenna with 15.3dBi at KK5O - Details www.texasantennas.com

A close-up shot of the KK5O 11el fitted with the G0KSC 'Antenna Balun' - More info HERE

The G0KSC Antenna Balun fitted on this FORCE12 11el OWL from another angle

VE1JF also installed the 17.9m Force12 inc version at 255' above salt water, awsome !!

Performance UK/USA Version

Forward Gain:                           15.16dBi at 50.250MHz

Front to Back Ratio:              24.84dBi at 50.250MHz

Peak Gain:                                 15.2dBi

Peak F/B:                                24.88dB

Bandwidth:                               500KHZ below 1.13:1

Build Dimensions for UK/USA Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   1.4965                                             12.7mm 1/2 inch Diameter tube

DE                       .301                               1.446                                               12.7mm  1/2 inch tube

D1                       .884                               1.398                                               12.7mm 1/2 inch Diameter tube

D2                     1.653                               1.325                                               12.7mm 1/2 inch Diameter tube

D3                     2.711                               1.3495                                             12.7mm 1/2 inch Diameter tube

D4                     4.619                               1.329                                               12.7mm 1/2 inch Diameter tube

D5                     6.871                               1.307                                               12.7mm 1/2 inch Diameter tube

D6                     9.322                               1.288                                               12.7mm 1/2 inch Diameter tube

D7                     11.822                              1.270                                              12.7mm 1/2 inch Diameter tube

D8                     14.424                              1.2645                                             12.7mm 1/2 inch Diameter tube

D9                     16.598                              1.288                                               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                                   1.4975                                            12mm Diameter tube

DE                       .301                               1.447                                              12mm Diameter tube

D1                       .884                               1.399                                              12mm Diameter tube

D2                     1.653                               1.326                                               12mm Diameter tube

D3                     2.711                               1.3505                                             12mm Diameter tube

D4                     4.619                               1.330                                               12mm Diameter tube

D5                     6.871                               1.308                                               12mm Diameter tube

D6                     9.322                               1.289                                               12mm Diameter tube

D7                     11.822                             1.271                                               12mm Diameter tube

D8                     14.424                             1.2655                                             12mm Diameter tube

D9                     16.598                             1.289                                               12mm Diameter tube

Fantastic Azimuth plot of this 11el 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