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!

A 14 element LFA Yagi for 70MHz with a 19.306mtr boom

Premium commercial versions of this antenna at Innovantennas

Note: If you do not see this antenna in an element diameter you would like, mail me!

The LFA design has a patent pending and all G0KSC designs are copyright. Any ham can build for their own use or those of a friend. Where profit or commerical gain exists, express permission of G0KSC must be sought.

If you suffer with noise from living in the city, this is another low-noise antenna from G0KSC

This antenna has been designed in order to minimise the upward and downward lobes typically seen the the EL plane on Yagi antennas. By doing this, a drastic reduction in pick up of unwanted noise in City locations is the result. The double bonus is the likelihood of reducing transmitted interference too. If you suffer with very bad noise on 70MHz and have room for an antenna of this size, Email me for details of the very high suppression version.

This antenna can be built with Metric or Imperial sized tubing:



2 x 7el 4m LFAs at G0VHF/P

Performance

16.53dBi @ 70.200MHz

F/B 30.98dB @ 70.200MHz

SWR: Below 1.1.1 from 70MHz to 70.600MHz

Construction

Antenna Dimensions for UK/USA sized tubing

Spacing                                Half Element Size  in Metres                Element Diameter

Reflector                0                              1.0555                                           3/8 inch or 10mm tube or rod

DE1                      .296                          .881  (.880 with 12mm tube)      1/2 inch or 12mm tube

DE2                      .692                          .881  (.880 with 12mm tube)      1/2 inch or 12mm  tube

D1                       1.245                          .9915                                           3/8 inch or 10mm tube or rod

D2                       2.352                         .966                                              3/8 inch or 10mm tube or rod

D3                       3.728                         .9495                                            3/8 inch or 10mm tube or rod

D4                       5.323                         .9345                                            3/8 inch or 10mm  tube or rod

D5                       7.007                         .9225                                            3/8 inch or 10mm tube or rod

D6                       8.765                         .910                                              3/8 inch or 10mm tube or rod

D7                       10.529                       .8975                                           3/8 inch or 10mm tube or rod

D8                       12.368                       .885                                              3/8 inch or 10mm tube or rod

D9                       14.210                       .878                                              3/8 inch or 10mm tube or rod

D10                     16.059                      .8735                                             3/8 inch or 10mm tube or rod

D11                     17.911                      .871                                               3/8 inch or 10mm tube or rod

D12                     19.306                      .886                                               3/8 inch or 10mm tube ot rod

The ends of DE1 and DE2 are connected together with 3/8 inch or 10mm tube or rod. the Feed point is the centre of DE1.

NOTE:

SWR will not read as per the graph below if you use a package with mininec or nec2. DO NOT Get your version of EZNEC confused with nec versions. Unless you have EZNEC Pro/4 you do not havew nec4. The swr graph is correct and confirmed within nec4 and through building this antenna.

DE1 and DE2 will have to be cut shorter than the above measurements in order to allow for the radius on the loop ends. Always adjust loop for best SWR.

Feedpoint gap 6-10mm this gap is not critical.

Please send photos of this antenna if you build it.

Azimuth Plot of this super antenna

The much improved elevation plot

Elevation plot at 20m up

The SWR curve is virtually the same with both metric and imperial sized tubing

Dave, G1OGY operating at G0VHFD had this to say ' The antenna was very sharp, it had a 30 degree beamwidth and if you went out side of this, there was nothing there !! This made it ideal beign able to block out some very strong signals coming in from behind the beam.. ' .

Any questions, please ask!