A 9el 12.5 Ohm 144MHz Optimised Wideband Low impedance (OWL) Very Low Temperature 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 section above.

Do not look at the gain figure of this antenna and compare with other 9 element 144MHz Yagis. Compare the gain, F/B and bandwidth together against other antennas of a similar boom length. With 14.26dBi and a boom less than 4.7M long and a single antenna sky temperature of 229.7 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 1.3MHz 1.1:1 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
• There is a second version of this antenna designed for SP3IYM - the 9OWL2IYM. Data and details at the bottom of this page

The 9el OWL fitted with a Folded Dipole by Vine antennas www.vinecom.co.uk

All 12.5Ohm OWLs have a 50Ohm feedpoint if fitted with a folded dipole

The 9el 2M OWL at ZL1RS

'The SWR dips are at 144.0 and 145.3 with a lift to 1.1:1 in between...' Bob ZL1RS

The 9el 12.5Ohm OWL built by SP3IYM

'Today I checked antenna on other one and SWR is realy nice. Antena has wide horizontal angle, but is realy quiet ! On 10el DK7ZB (6m long) I had much bigger noise on the band...  I tested it today at 7m above the ground. I heard 4 beacons with nice signal (OZ7IGY/B 470km). Also F/B is good. I'm located 1km from SR3VHX beacon (5W into 7dBd) 144.481. but i haven't problems with reading OZ7IGY at 144.471 when back of antenna is pointing to vhx ;)'

Performance UK/USA Version

Forward Gain:                           14.26dBi at 144.300MHz

Front to Back Ratio:              30.19dBi at 144.300MHz

Peak Gain:                               14.30dBi

Peak F/B:                                30.41dB

Bandwidth:                              1.3MHz below 1.1:1

Sky Temp. TA:                        229.7 Kelvin

G/T:                                        -9.37dB

Four bay array (in metres) - 2.85V x 3.0H

Sky Temp. TA:                        225.0 Kelvin

G/T:                                        -3.54dB

Gain:  19.98dBi

Build Dimensions for UK/USA Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   .5145                                           3/8 inch tube

DE                       .132                               .4935                                           1/2 inch tube

D1                       .371                               .4795                                           3/8 inch tube

D2                       .857                               .4645                                           3/8 inch tube

D3                     1.514                               .4535                                           3/8 inch tube

D4                     2.285                               .444                                             3/8 inch tube

D5                     3.103                               .434                                             3/8 inch tube

D6                     3.965                               .4235                                           3/8 inch tube

D7                     4.746                               .420                                             3/8 inch tube

Build Dimensions for European Version

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   .514                                            10mm tube

DE                       .132                               .494                                            12mm tube

D1                       .371                               .479                                            10mm tube

D2                       .857                               .464                                            10mm tube

D3                     1.514                               .453                                            10mm tube

D4                     2.285                               .4435                                          10mm tube

D5                     3.103                               .4335                                          10mm tube

D6                     3.965                               .423                                            10mm tube

D7                     4.746                               .4195                                          10mm tube

SP3IYM version 9LFA2IYM

Forward Gain:                           14.35dBi at 144.300MHz

Front to Back Ratio:             27.51dBi at 144.300MHz

Peak Gain:                               14.37dBi

Peak F/B:                                28.34dB

Sky Temp. TA:                        227.9 Kelvin

G/T:                                        -9.24dB

Four bay array (in metres) - 2.88V x 3.1H

Sky Temp. TA:                        224.1 Kelvin

G/T:                                        -3.41dB

Gain:  20.09dBi

Element           Spacing in metres Half element Length in metres            Element Notes

Reflector               0                                   .5145                                            6mm tube

DE                       .160                               .4895                                            12mm tube

D1                       .444                               .4835                                            6mm tube

D2                       .953                               .470                                              6mm tube

D3                     1.619                               .460                                              6mm tube

D4                     2.402                               .451                                              6mm tube

D5                     3.228                               .443                                              6mm tube

D6                     4.130                               .431                                              6mm tube

D7                     4.913                               .430                                              6mm tube

Antenna Plots

Fantastic Azimuth plot of this 9el 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