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A 6 element LFA Yagi for 70MHz with a 4.9mtr boom - 6LFA4KSC

Revised August 2010 V1.2

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.

 

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. However, this version is not a model with optimum suppression which would see a reduction in forward gain of 1dB. 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 6el at G3NPI (lucky lad)

 

 

the 6el 4m LFA at GW0EZY






The 6el 4m LFA installed at G0KSC (tower lowered) What's the object above the boom? G0KSC Antenna Balun

 

 

The 4.9m long 70MHz 6el LFA above a 6.0m long 50Mhz 6el LFA at G8FJG. G0KSC Antenna Balun on both

 

Performance

11.84dBi @ 70.250MHz

29.33dB @ 70.250MHz

SWR: Below 1.1.1 from 70MHz to 70.900MHz

Construction

 

 

For full details of how to make the LFA, read here: http://www.g0ksc.co.uk/making-the-lfa-loop.html

Antenna Dimensions for UK/USA sized tubing - European version below

Spacing                      Half Element Size  in Metres              Element Diameter

Reflector                0                              1.0595                                           3/8 inch

DE1                      .266                          .8835                                             1/2 inch

DE2                      .664                          .8835                                             1/2 inch

D1                        1.120                        .9935                                             3/8 inch

D2                       2.139                         .9635                                             3/8 inch

D3                       3.426                         .9375                                             3/8 inch

D4                       4.883                         .879                                               3/8 inch

 

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

 

Antenna Dimensions for European sized tubing

Spacing                      Half Element Size  in Metres              Element Diameter

Reflector                0                              1.060                                           10 mm

DE1                      .266                          .882                                              12 mm

DE2                      .664                          .882                                              12 mm

D1                        1.120                        .994                                              10 mm

D2                       2.139                         .964                                              10 mm

D3                       3.426                         .938                                              10 mm

D4                       4.883                         .875                                              10 mm

 

The ends of DE1 and DE2 are connected together with 3/8 inch 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.

 

 

Pattern is identical when using metric or imperial tubing. This is the Elevation Plot

 

 

Azimuth Plot of this super antenna

 

 

SWR Plot

 


Any questions, please ask!

 

Justin G0KSC

 
 
 
 

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