An 11el 12.5 Ohm 144MHz Optimised Wideband Low impedance (OWL) Very Low Temperature Yagi

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 11 element 144MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With 15.28dBi and a boom less than 6.3M long and a single antenna sky temperature of 225.1 Kelvin, this antenna will be a winner for all those seeking the most quiet antenna of this size for 2M. Class leading G/T figures too! This antenna also has an incredible 900KHz 1.12:1 bandwidth too!

PLEASE NOTE:

• 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 insulators similar to G0KSC. If through boom/insulator/element bolts are used, add 3mm
• This is a Very Low Temperature antenna, ideal for EME work

The 11el 12.5Ohm OWL at G0KSC

Screen shot of the first EME QSO on this single 11el Yagi with no elevation and only 100 watts

Performance UK/USA Version

Forward Gain:                           15.28dBi at 144.300MHz

Front to Back Ratio:                 27.26dBi at 144.300MHz

Peak Gain:                               15.31dBi

Peak F/B:                                27.31dB

Bandwidth:                              900KHz below 1.12:1

Sky Temp. TA:                        225.1 Kelvin

G/T:                                        -8.24dB

Four bay array (in metres) - 3.3V x 3.5H

Sky Temp. TA:                         219.9 Kelvin

G/T:                                        -2.33dB

Gain:     21.09dBi

Note: all G/T and sky temperature figures at 144.100MHz

Build Dimensions for UK/USA Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   .5155                                           3/8 inch tube

DE                       .111                               .496                                             1/2 inch tube

D1                       .293                               .483                                             3/8 inch tube

D2                       .718                               .4685                                           3/8 inch tube

D3                     1.328                               .457                                             3/8 inch tube

D4                     2.081                               .4465                                           3/8 inch tube

D5                     2.895                               .440                                             3/8 inch tube

D6                     3.739                               .4335                                           3/8 inch tube

D7                     4.619                               .425                                             3/8 inch tube

D8                     5.516                               .418                                             3/8 inch tube

D9                     6.297                               .4245                                           3/8 inch tube

Build Dimensions for European Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   .515                                            10mm tube

DE                       .111                               .4965                                          12mm tube

D1                       .293                               .4825                                          10mm tube

D2                       .718                               .468                                            10mm tube

D3                     1.328                               .4565                                          10mm tube

D4                     2.081                               .446                                            10mm tube

D5                     2.895                               .4395                                          10mm tube

D6                     3.739                               .433                                            10mm tube

D7                     4.619                               .4245                                          10mm tube

D8                     5.516                               .4175                                          10mm tube

D9                     6.297                               .424                                            10mm tube

Antenna Plots

Fantastic Azimuth plot of this low temperature 11el 144MHz 12.5Ohm OWL Yagi

The Elevation plot is really clean too. A super quiet antenna, find one the same size that is more quiet!

A Super quiet antenna that is wideband? Another first from G0KSC. 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 three elements. My 'secret' to wide band low impedance antennas I now release for all to use.

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

Justin G0KSC