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6el 6.4mtr Boom LFA

A High-Gain 6 element LFA Yagi with a 6.4 metre Boom for 50MHz

Revised 22nd January 2010 V1.0

 

Premium commercial versions of this antenna at Innovantennas

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.

 

Note there are several versions of this antenna, the lower version is specifically designed for stacking and has highly suppresed elevation lobes.

 

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

This antenna has been designed with performance in mind and provides optimum performance for the 6.4 metre boom length. As with all of my second generation LFA's wide bandwidth has been modeled into the antenna to ensure maximum performance without matching losses.

Please read the 'how to make the LFA Loop' page here

 

2 x 6.4m 6el at VK6OX

 

 

2 x 6.4m long 6el 50MHz LFAs at ZL1RS

 

 

CT1GPZ has his 6.4m 6el 50MHz LFA between HF antenna wit no effect.

 

The 6.4m long 6LFAKYZ 6el 6m LFA sits between 2 x 11el 2m LFAs at KA0KYZ - Details of this variant are below

 

 

The 6el 6.4m boom LFA at G0CHE

 

 

Performance

Forward Gain:                                   11.63dBi at 50.150MHz

Front to Back Ratio:                           32.27dB at 50.150MHz

Peak Gain:                                        11.69dBi

Peak F/B:                                          32.43dB

Build Dimensions using 1/2 inch or 13/12mm loop 3/8 inch / 10mm parasitic elements

Element                             Spacing in metres Half element Length in metres

Reflector                                0                                                                       1.490                3/8 inch or 10mm elements

DE1                                       .298                                       (1.245)                 1.246              1/2 inch  (12mm)

DE2                                       .823                                      (1.245)                  1.246              1/2 inch  (12mm)

D1                                        1.428                                                                 1.3875                3/8 inch or 10mm elements

D2                                        2.784                                                                 1.3485                3/8 inch or 10mm elements

D3                                        4.561                                                                 1.322                  3/8 inch or 10mm elements

D4                                        6.399                                                                 1.2425                3/8 inch or 10mm elements

Notes:

DE1 and DE2 are joined at the ends by either 3/8 inch or 10mm tube when 1/2 inch or 13/12mm DE1 and DE2 are used. these end sections should be

Feed point is ALWAYS the centre of DE1

Please read the 'how to make the LFA Loop' page here

 

6el 6LFA6KYZ version using 3/4 inch elements

 

Performance

Forward Gain:                                   11.77dBi at 50.150MHz

Front to Back Ratio:                           33.15dB at 50.150MHz

Peak Gain:                                        11.80dBi

Peak F/B:                                          33.23dB

Build Dimensions using 3/4 inch elements

Element                             Spacing in metres Half element Length in metres

Reflector                                0                                                                       1.486                3/4 inch elements

DE1                                       .298                                                                  1.254                 3/4 inch  (end sections 5/8 inch)

DE2                                       .822                                                                  1.254                 3/4 inch  (end sections 5/8 inch)

D1                                        1.401                                                                 1.382                  3/4 inch  elements

D2                                        2.767                                                                 1.344                  3/4 inch  elements

D3                                        4.530                                                                 1.311                  3/4 inch  elements

D4                                        6.399                                                                 1.240                  3/4 inch  elements

Notes:

DE1 and DE2 are joined at the ends by either 3/8 inch or 10mm tube when 1/2 inch or 13/12mm DE1 and DE2 are used. these end sections should be

Feed point is ALWAYS the centre of DE1

Please read the 'how to make the LFA Loop' page here

 

Performance plot of this fantastic antenna

 

Excellent elevation plot too

 

Antenna layout showing the feedpoint (red circle) at the back of the loop closest to the reflector

 

SWR Plot

 

Stacking Version of this Antenna using UK/USA sized material

Performance

Forward Gain:                                   11.45dBi at 50.150MHz

Front to Back Ratio:                           34.31dB at 50.150MHz

Peak Gain:                                        11.47dBi

Peak F/B:                                          35.23dB

Build Dimensions using 1/2 inch or 13/12mm loop 3/8 inch / 10mm parasitic elements

Element                             Spacing in metres Half element Length in metres

Reflector                                0                                                                       1.487                3/8 inch elements

DE1                                       .298                                                                  1.249              1/2 inch 

DE2                                       .826                                                                  1.249              1/2 inch 

D1                                        1.326                                                                 1.405                  3/8 inch elements

D2                                        2.578                                                                 1.3625                3/8 inch elements

D3                                        4.377                                                                 1.317                  3/8 inch elements

D4                                        6.399                                                                 1.2265                3/8 inch elements

Notes:

DE1 and DE2 are joined at the ends by  3/8 inch  tube. Adjust loop width for best SWR

Feed point is ALWAYS the centre of DE1

Please read the 'how to make the LFA Loop' page here

 

 Version using 10/12mm elements

 

Performance

Forward Gain:                                   11.44dBi at 50.150MHz

Front to Back Ratio:                           34.85dB at 50.150MHz

Peak Gain:                                        11.45dBi

Peak F/B:                                          35.40dB

Build Dimensions using 3/4 inch elements

Element                             Spacing in metres Half element Length in metres

Reflector                                0                                                                       1.4865               10mm elements

DE1                                       .298                                                                  1.252                  12mm  (end sections 8/10mm)

DE2                                       .822                                                                  1.252                  12mm  (end sections 8/10mm)

D1                                        1.401                                                                 1.4045                10mm  elements

D2                                        2.767                                                                 1.362                  10mm  elements

D3                                        4.530                                                                 1.3165                10mm  elements

D4                                        6.399                                                                 1.226                  10mm  elements

Notes:

DE1 and DE2 are joined at the ends by either 8 or 10mm tube. these end sections should be adjusted for best SWR.

Feed point is ALWAYS the centre of DE1

Please read the 'how to make the LFA Loop' page here

 

Stacking distances (Both versions):

 

Best Pattern (lowest noise):    4.8m

Gain:                                               14.06dBi @ 50.150MHz

F/B:                                                  35.37dB @ 50.150MHz


High Performance:                     5.2m

Gain:                                               14.21dBi @50.150MHz

F/B:                                                  34.17dBi @ 50.150MHz

 

Azimuth Plot of this 6el LFA Stacker

 

 

And now the single Antenna Elevation plot

 

 

Freespace elevation plot at 4.7m spacing

 

 

Freepsace plot at 4.8m spacing

 

 

Freespace plot at 5.2m spacing

 

 

Elevation plot with 4.7m spacing at 12m above ground (bottom antenna)

 

 

Elevation plot with 4.8m spacing at 12m above ground (bottom antenna)

 

 

Elevation plot at 5.2m spacing at 12m above ground (bottom antenna)

 

 

Azimuth plot when 2 antennas are stacked

 

 

SWR Plot for this antenna

                             

 
 
 
 

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