Canvey Island, Essex, England Justin@g0ksc.co.uk
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Twin boom quad
144MHz LFA Yagis
144MHz LFA Yagis

Low Noise LFA Yagis designed by G0KSC free to build for personal use.

144MHz LFA Yagis
70cms LFA Yagis
70cms LFA Yagis
Twin-Boom G0KSC Quads
G0KSC Twin-Boom Quads
Twin-Boom G0KSC Quads
G0KSC Custom Dish feeds - Above installation @ HB9Q
Custom low-noise dish feeds
Custom low-noise dish feeds
G0KSC Custom Dish Feeds

Above installation @ HB9Q

G0KSC Custom Dish feeds - Above installation @ HB9Q
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Read Time: 4 - 8 minutes
A 7 element OWA Yagi for 21MHz with a 16.3mtr boom

Premium commercial versions of this antenna at Innovantennas

I WILL MODEL THIS ANTENNA IN ANY TUBE SIZE OR TAPER SECHDULE FOR YOU, CONTACT ME VIA EMAIL

This is a high-gain, wideband OWA (Optimised Wideband Array) Yagi which covers the whole of the 15m band with an SWR of less than1.1:1. It has options with both UK/USA and European sized tube and has a 3 section taper.

This Antenna has been modelled using NEC4 and confirmed by FEKO. This is thousands of dollar of the very latest antenna design software available and the results are highly accurate. When loading into your software, you will see similar SWR but not the same. Please do not alter the model, build to these dimensions for the best results.

Contact me if you are unsure what correction (if any) you require for the element holders/stand-offs you will use or any other questions you may have.

Antenna Layout and Construction:

Performance

11.89dBi @ 21.200MHz

23.86dB @ 21.20MHz

SWR: Below 1.1.1 from 21MHz to 21.450MHz

Construction details

Refer to the above drawings

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

Taper: Mid Section, 5/8 inch tube (total length 4.8m). Outer section 1/2 inch 2.4m long. End sections as per below schedule

                          Spacing                  End Section Length   (All below sizes in Metres)               

Reflector                0                              1.201                                          

DE1                      2.064                        1.133                                           

D1                        2.798                           .964                                           

D2                        4.881                           .948                                           

D3                        8.150                           .879                                           

D4                        12.452                        .820                                           

D5                        16.835                        .666                                           

Antenna Dimensions for European sized tubing

Taper: Mid Section, 16mm tube (total length 4.8m). Outer section 13mm tube 2.4m long. End sections as per below schedule

                         Spacing                      End Section Length  (All below sizes in Metres)          

Reflector                0                              1.199                                            

DE1                      2.064                         1.130                                             

D1                        2.798                          .962                                             

D2                        4.881                         .946                                             

D3                        8.150                         .877                                             

D4                      12.452                         .818                                             

D5                      16.835                         .664                                            

Polar Plots

Azimuth Plot of this super antenna

Elevation plot of this antenna

Elevation plot of this antenna at 15M above ground

SWR Plot

Any questions, please ask!

Justin G0KSC

Read Time: 5 - 9 minutes
A 6 element LFA Yagi for 70MHz with a 4.9mtr boom - 6LFA4KSC

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? 

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

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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