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A Low-Noise 'Urban' 6 element LFA Yagi for 50MHz

Revised 12th July 2009 V1.2

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

Download the EZNEC Project files for this antenna HERE

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 supression 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.

Note: There are TWO versions of this antenna below. One using Metirc tube sizes, the other using Imperial so anyone anywhere should be in a position to build this.

 

A 6el 50MHz LFA and a 7el 70MHz LFA at PA2J

 

Installed at JA2DDN

 

The 6el 50MHz LFA installed at EA6BB

 

The 6.8m Long 6el LFA installed at ZS6JON with a 6el 5.32m long 4m LFA on top

 

 

K7JA built his 6.8m 6el 50MHz LFA out of 'copper and wood' and still sees a flat SWR with super pattern !!

 

 

Built by KG4HG, Orlando Florida

 

6el LFA at PA3GND, DXCC # 842 for 6 Meters

 

The PA2V 6.8m 6el 50MHz LFA

 

 

2x 6el 6.8m boom LFAs at HB9BLF

 

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

 

Performance European Version                             UK/USA Version

Forward Gain:                                   11.88dBi at 50.150MHz                 11.87dBi at 50.150MHz

Front to Back Ratio:                        27.47dB at 50.150MHz                 27.51dBi at 50.150MHz

Peak Gain:                                        11.94dBi                                           11.9dBi

Peak F/B:                                       27.64dB                                           27.85dB

Bandwidth:                                     500KHz below 1.1:1                       500KHZ below 1.1:1

Download the EZNEC Project files for this antenna HERE

 

Build Dimensions for European Version

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                  0                                                          1.483                                          10mm or 3/8 inch Diameter tube or solid rod

DE1                                        .326                                                      1.243                                             13mm or 1/2 inch Tube

DE2                                        .87                                                      1.243                                               13mm or 1/2 inch Tube

D1                                         1.536                                                      1.393                                          10mm or 3/8 inch Diameter tube or solid rod

D2                                         2.964                                                     1.355                                           10mm or 3/8 inch Diameter tube or solid rod

D3                                         4.877                                                     1.315                                           10mm or 3/8 inch Diameter tube or solid rod

D4                                         6.867                                                     1.235                                           10mm or 3/8 inch Diameter tube or solid rod

Notes:

DE1 and DE2 are joined at the ends by either 10mm tube

Feed point is the centre of DE1

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

Construction

This antennas has been designed using 1/2 inch elements and the loop section is made of 2 x 1/2 inch lengths with 3/8 inch sections inserted into each end in order to complete the loop. The loop is feed at the back nearest the reflector. Details of the loop layout as per picture below:

Dimensions to be added shortly

 

 

 

 

 
 
 
 

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