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/BalunDo 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.
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
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