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6el 7.3mtr Boom LFA

A High-Gain 6 element LFA Yagi with a 7.3 metre Boom for 50MHz

 

Revised 27th July 2009 V1.3

EU version added February 2010 see below 12mm elements

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 sort.

Note, this LFA is not suited for location where high suppression of noise is required due to the existence of lobe elevation plane lobes. Where the best in noise suppression is required, chose a shorter 6el or a small 7el.

 

This antenna has been designed with performance in mind and provides optimum performance for the 7.3 metre boom length. As with all of my second generation LFA's wide bandwidth has been modelled into the antenna to ensure maximum performance without matching losses.

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

 

The 7.3m long 6el at OZ6ABA

 

The 7.3m 6el LFA at LZ1DP

 

Built my 9A9T 2011

 

The G0KSC 6 mtr Antenna, the 7.3 mtr long 6el LFA - installed 28th July 2009

 

The 6el at SP3OCC installed 2010

 

The same antenna built by VK4DDC

 

The 6el 7.3M long 50MHz LFA of OE4VIE

 

The 7.3M long 6el 50MHz LFA as built by UK8OM

 

EI2GLB's 6el 7.3m 6m LFA with 7el 4m version on top

 

'on 6m I have worked 5 new ones this year A92,A7,SU,ST & JY and usuals in Carib and some NA as well
On 4m I worked the First EI-OH on the band as also worked a load of OZ's, But I am QRT on 4m now until I fix my 847'

Trevor EI2GLB

 

Performance Standard Loop                              16mm or 0.63 Inch Loop

Forward Gain:                                   12.32dBi at 50.150MHz                  12.33dBi at 50.150MHz

Front to Back Ratio:                           22.87dB at 50.150MHz                  23.17dBi at 50.150MHz

Peak Gain:                                        12.38dBi                                     12.4dBi

Peak F/B:                                          25.46dB                                     25.46dB

Build Dimensions using 1/2 inch or 13mm elements

Element                             Spacing in metres Half element Length in metres

Reflector                                0                                                               1.488

DE1                                       .333                                                          1.236

DE2                                       .889                                                          1.236 (1.234 with 5/8 inch or 16mm loop)

D1                                        1.66 (1.58 with 5/8 inch or 16mm loop)          1.377

D2                                        3.386                                                         1.34

D3                                        5.286                                                         1.324

D4                                        7.243                                                          1.281

Notes:

DE1 and DE2 are joined at the ends by either 3/8 inch or 10mm tube when 1/2 inch or 13mm DE1 and DE2 are used. these end sections should be 1/2 inch or 13mm when 5/8 inch or 16mm main loop sections are used. If in doubt, Email me!

Feed point is ALWAYS the centre of DE1

 

Build Dimensions using 12mm elements

Element                             Spacing in metres Half element Length in metres

Reflector                                0                                                               1.4865

DE1                                       .330                                                          1.235 (Loop ends 10mm)

DE2                                       .884                                                          1.235 (Loop Ends 10mm)

D1                                        1.653                                                         1.378

D2                                        3.385                                                         1.340

D3                                        5.320                                                         1.320

D4                                        7.299                                                          1.281

Notes:

DE1 and DE2 are joined at the ends by 10mm tube when 12mm DE1 and DE2 are used. If in doubt, Email me!

Feed point is ALWAYS the centre of DE1

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

 

Performance plot with 13mm or 1/2 inch elements

 

Plot with 16mm or 5/8 inch driven loop with all other elements 1/2 inch or 13mm ( see build info)

 

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

 

SWR with 1/2 inch elements

 

SWR with 13mm elements

 
 
 
 

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