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A Low-Noise 'Urban' 14 element LFA Yagi for 50MHz

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.

I am not sure too many of these will be built due to size but I guess I maybe surprised. This is the ultimate single Yagi for 50MHz. If you build one, I must come and work the DX with it!

Like the 9, 10, 11, 12 and 13 element version before it, this antenna has been designed with light-weight in mind and optimum performance through single piece elements. It has all the common attributes of an LFA Yagi, Flat SWR, Excellent Gain, fantastic Front to Back ratio and suppressed unwanted lobes.

A True DX'ers antenna and at over 25 metres long, not for every ham in the neighbourhood! However, this antenna does have a massive .3dB advantage over the smaller 13 element version and at these levels of gain, that can make quite a difference.In addition, I have supressed further the lobes around the centre of the antenna in order to improve receive performance even more.

Both European and UK/USA versions are available. Build and construction details are below and EZNEC files are available for download on the download page.

The 14 element LFA Yagi for 50MHz. How it will look when completed

4nec2 (with nec4 engine) Elevation plot of the 14el 50MHz LFA

14el 50MHz Azimuth plot from the 4nec2 antenna modelling package

 

SWR as presented in the 4nec2 antenna modelling package using nec4.1 Double Precision calculation engine

PLEASE NOTE:

Performance European Version                             UK/USA Version

Forward Gain:                                   16.44dBi at 50.150MHz                 16.43dBi at 50.150MHz

Front to Back Ratio:                           30.91dB at 50.150MHz                  31.16dBi  at 50.150MHz

Peak Gain:                                       16.46dBi                                           16.45dBi

Peak F/B:                                          34.6dB                                           35.53dB

Bandwidth:                                       500KHz below 1.1:1                       500KHZ below 1.1:1

Build Dimensions for UK/USA Version

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                 0                                                             1.484                                               3/8 Diameter tube or solid rod

DE1                                       .389                                                         1.231                                               1/2 inch Tube

DE2                                       .954                                                         1.231                                               1/2 inch Tube

D1                                         1.714                                                       1.394                                               3/8 Diameter tube or solid rod

D2                                         3.303                                                       1.363                                               3/8 Diameter tube or solid rod

D3                                         5.231                                                       1.341                                               3/8 Diameter tube or solid rod

D4                                         7.481                                                       1.322                                               3/8 Diameter tube or solid rod

D5                                         9.867                                                       1.305                                               3/8 Diameter tube or solid rod

D6                                         12.341                                                     1.289                                               3/8 Diameter tube or solid rod

D7                                         14.91                                                       1.272                                               3/8 Diameter tube or solid rod

D8                                         17.478                                                     1.257                                               3/8 Diameter tube or solid rod

D9                                         20.164                                                     1.24                                                 3/8 Diameter tube or solid rod

D10                                       22.761                                                     1.213                                               3/8 Diameter tube or solid rod

D11                                       25.178                                                     1.193                                               3/8 Diameter tube or solid rod

D12                                       27.755                                                     1.172                                               3/8 Diameter tube or solid rod

Notes:

DE1 and DE2 are joined at the ends by 3/8 tube

Feed point is the centre of DE1

SWR Plot for the UK/USA version of the G0KSC 14el 50MHz LFA Yagi

Build Dimensions for European Version - mail me if you need 13mm tube driven loop sizing

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           1.483                                               10mm Diameter tube or solid rod

DE1                                       .389                                                      1.229                                                12mm Tube

DE2                                       .954                                                      1.229                                                12mm Tube

D1                                         1.713                                                    1.394                                               10mm Diameter tube or solid rod

D2                                         3.303                                                    1.362                                               10mm Diameter tube or solid rod

D3                                         5.231                                                    1.34                                                 10mm Diameter tube or solid rod

D4                                         7.481                                                    1.321                                               10mm Diameter tube or solid rod

D5                                         9.867                                                    1.304                                               10mm Diameter tube or solid rod

D6                                        12.341                                                   1.288                                               10mm Diameter tube or solid rod

D7                                        14.91                                                     1.271                                               10mm Diameter tube or solid rod

D8                                        17.478                                                   1.256                                               10mm Diameter tube or solid rod

D9                                        20.164                                                   1.239                                               10mm Diameter tube or solid rod

D10                                      22.761                                                   1.212                                               10mm Diameter tube or solid rod

D11                                      25.355                                                   1.192                                               10mm Diameter tube or solid rod

D12                                      27.755                                                   1.171                                               10mm Diameter tube or solid rod

Notes:

DE1 and DE2 are joined at the ends by 10mm tube

Feed point is the centre of DE1

SWR Plot for the UK/USA version of the G0KSC 14el 50MHz LFA Yagi

Antenna Elevation Plot in EZNEC Pro/4

European version Azimuth Plot in EZNEC Pro/4

As always, any questions please ask!

Justin G0KSC