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A 8el 12.5 Ohm 50MHz Optimised Wideband Low impedance (OWL) Yagi
Revised 31st January 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 8 element 50MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With almost 13.3dBi and a boom less than 10M 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 more details
The 8el OWL installed at ZL1RS
Performance UK/USA Version
Forward Gain: 13.26dBi at 50.150MHz
Front to Back Ratio: 26.85dBi at 50.150MHz
Peak Gain: 13.27dBi
Peak F/B: 26.90dB
Bandwidth: 500KHZ below 1.12:1
Build Dimensions for UK/USA Version
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 1.5145 12.7mm 1/2 inch Diameter tube
DE .200 1.460 12.7mm 1/2 inch tube
D1 .537 1.4235 12.7mm 1/2 inch Diameter tube
D2 1.575 1.3775 12.7mm 1/2 inch Diameter tube
D3 3.346 1.342 12.7mm 1/2 inch Diameter tube
D4 5.469 1.315 12.7mm 1/2 inch Diameter tube
D5 7.741 1.293 12.7mm 1/2 inch Diameter tube
D6 9.782 1.283 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
DE .200 1.4615 12mm Diameter tube
D1 .532 1.4255 12mm Diameter tube
D2 1.575 1.380 12mm Diameter tube
D3 3.346 1.344 12mm Diameter tube
D4 5.469 1.3165 12mm Diameter tube
D5 7.741 1.2955 12mm Diameter tube
D6 9.782 1.2815 12mm Diameter tube
Fantastic Azimuth plot of this 8el 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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8el 12.5Ohm 9.8m
