G0KSC SC0609L 9el 50Mhz Yagi Antenna with a 12.2 Metre Length Boom

updated June 2010

Please read the whole page, there are several versions of this antenna listed.

This antenna has been redesigned and represents what i beleive to the the 'ideal boom length' for an OWA direct feed 50Ohm Yagi. This can be seen in the model in the super flat SWR, the high levels of F/B ratio along with the excellent gain and pattern.

The model below is designed with 12.7mm / 1/2 inch elements. If you require a version of this antenna with another diameter wire, Email me and I will remodel. It is NOT POSSIBLE to simply resize the elements when using a VERY different diameter wire and get the best performance possible. Element positions also need to change for the ideal antenna to be achieved again. Please read all the way down this page, there are other versions of this antenna using tapered elements too. As I have more requests, I will remodel in other element diameters and tapers and pulbish those too.

Enjoy the antenna and if you build, Please Send me photos!

Dimensions in Metres

Element spacing:

• Ref =      0
• Driven =  .838
• D1 =       1.012
• D2 =       1.946
• D3 =      3.588
• D4 =      5.562
• D5 =      7.750
• D6 =      10.154
• D7 =      12.234

Element sizes per element half:

• Ref =       1.477
• Driven =   1.461
• D1 =        1.3915
• D2 =        1.379
• D3 =        1.346
• D4 =        1.322
• D5 =        1.302
• D6 =        1.278
• D7 =        1.272

Performance figures @ 50.150Mhz:

• Froward Gain: 13.93dBi free space
• Front to Back: 28.12dB
• Radiation angle at 10 Metres above ground: 6 degrees

Azimuth Plot

Elevation Plot

This fantastic antenna at 20m up

An Excellent SWR to go with the fantastic pattern!