G0KSC SC14412S 12el 144Mhz Yagi Antenna with a 6.9 Metre Length Boom

Premium commercial versions of this antenna at Innovantennas

Please read the whole page, If you do not see the diameter tubing you need to have this antenna designed in or require tapered elements, Email me!

This antenna has been redesigned and represents what I beleive to the the 'ideal boom length' for an OWA direct feed 50 Ohm Yagi with 12 elements on 144MHz. 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 very low-noise pattern.

The model below is designed with 12.7mm / 1/2 inch dipole and 8mm - 5/16inch 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, Spacing and element diameters MUST be re-optimised to reproduce the best antenna possible.

REMEMBER, Gain does not make the best antenna on 2m. F/B, SWR Banwdith, Pattern Stability, Side Lobe suppression, Sky Teperature and G/T all play a role. Choose an antenna based on gain alone and you will never know what you are missing (mainly weak signals) !!

This Antenna has been designed in order to provide amazing stability in all weathers; Rain, Ice and Snow. Little effect will be seen from close-by objects (including other antennas) and impedance is contstant. Losses are at an absolute minimum with this antenna ensuring long-term, trouble-free, any-time operating and usage.

Dimensions in Metres - all tubing 1/2 inch / 13mm diameter dipole and 8mm / 5/16 inch parasitic elements, mail for other sizes and tapered elements

Element spacing:

• Ref =      0
• Driven =  .295
• D1 =       .397
• D2 =       .778
• D3 =      1.371
• D4 =      2.076
• D5 =      2.840
• D6 =      3.642
• D7 =      4.459
• D8 =      5.309
• D9 =      6.197
• D10 =    6.934

Element sizes per element half:

• Ref =       .5105
• Driven =   .5065 (.507 for 12mm dipole)
• D1 =         .480
• D2 =         .471
• D3 =         .461
• D4 =         .4525
• D5 =         .4475
• D6 =         .443
• D7 =         .437
• D8 =         .428
• D9 =         .418
• D10 =      .4045

Note: ALL elements 8mm (5/16inch) dipole is 1/2 inch with 12mm dipole figures in brackets.

Performance figures @ 144.300Mhz:

• Froward Gain: 15.48dBi free space
• Front to Back: 31.5dB
• SWR Bandwidth - 2MHz below 1.1:1

Sky Temperature @ 144.100MHz = 224.9 Kelvin

G/T @ 144.100MHz = -8.04dB

Stacking information:

Vertical Stacking - 3.4M

Horizontal Stacking - 3.6M

Sky Temperature (4 antennas) @ 144.100MHz = 221.5 Kelvin

G/T @ 144.100MHz = -2.12dB

4 x Gain: 21.33dBi

Azimuth Plot

Elevation Plot

This fantastic antenna at 12m up

An Excellent SWR to go with the fantastic pattern!

Remeber, mail me if you have different diameter tube requirements and send photos of built antenna!