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A Low-Noise 'Urban' 5 element LFA Yagi for 144-146MHz

 

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 one is really nice and compact, has good bandwdith (over 1MHz 1.1:1) and yet has maintained an excellent pattern at the same time. Stacked in 4, you would not be unhappy with this very low-noise LFA for EME working. This antenna will be particularly good for EME purposes due to it's very low noise (Sky Temperature) and excellent G/T figures. See the bottom of this page for more information.

PLEASE NOTE:

4 stacked 5el LFAs at HB9FAP

'hi Justin. Hope U r fine. I am now at the VHF QTH and have mounted your 4x5el yagis.

I have mounted also 2x13 CC so that I can compare the 2 antennas systems. I am very

positive surprised abt your antennas! They are at least so good as the 2x13CC and even

a bit better! The lobe is very nicely broad and clearly (of course) wider than the 2x13CC.

I think they will do a very good job on MS during the coming MS Sprint on thursday.'

Fabio HB9FAP

Note: performance figures centred on 144.300MHz the centre SSB frequency

Performance

Forward Gain:                   11.17dBi at 144.400MHz

Front to Back Ratio:          19.93dBi at 145.100MHz

Bandwidth:                                  1MHZ below 1.1:1 (2MHz 1.3:1)

Azimuth Plot of this wideband 5el 144MHz LFA

Elevation Plot

SWR Plot from 144MHz to 146MHz

Build Dimensions for UK/USA/European version Version

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           .513                                              3/8 Inch or 10mm Diameter tube or solid rod

DE1                                       .122                                                      .433 (.432 on Euro sizes)                 1/2 inch or 12mm Tube

DE2                                       .299                                                      .433  (.432 on Euro sizes)                1/2 inch or 12mm Tube

D1                                         .558                                                      .4685                                              3/8 inch  or 10mm Diameter tube or solid rod

D2                                        1.125                                                     .446                                              3/8 inch or 10mm Diameter tube or solid rod

D3                                        1.789                                                     .426                                              3/8 inch or 10mm Diameter tube or solid rod

Notes:

DE1 and DE2 are joined at the ends by either 10mm or 3/8inch tube. Feed point is the centre of DE1

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

As always, any questions please ask!

Justin G0KSC