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
