11el 144MHz Low Noise LFA

A Low-Noise 'Urban' 11 element LFA Yagi for 144MHz

If you suffer with noise from living in the city, this is another low-noise antenna from G0KSC

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.

This antenna has been built and tested with a version of this one being marketed by Vine Antennas. Again, like the 9 element version before it, this antenna has better allround performance than any other antenna of the same boom length, included within the VE7BQH G/T table.

This antenna is particularly good for EME purposes due to the class leading low noise (Sky Temperature) and G/T figures mentioned above. See the bottom of this page for more information.

PLEASE NOTE:

• This antenna WILL NOT show the true SWR in any antenna modelling package unless you are using one which uses the latest NEC4 calculation engine. Do not confuse nec versions with EZNEC versions. Unless you have EZNEC pro/4 you are using nec2 NOT nec4
• There are two sets of measurements listed below. One uses imperial sizes, the other uses metirc sizes. Ensure you use the correct one for the material you have
• 'within one or two millimetres' Will not do! take the time to ensure you get the spacing ant element lengths as close as you possibly can to the measurements below to ensure good, solid performance
• Please read the 'how to make the LFA Loop' page here

Download the European and UK/USA versions of this antenna in EZNEC format HERE

An 11 Element 144MHz LFA on test

Download the European and UK/USA versions of this antenna in EZNEC format HERE

Note: Performance figures given at 144.100MHz, the EME centre frequency

Performance European Version                             UK/USA Version

Forward Gain:                                   15.25dBi at 144.100MHz                 15.27dBi at 144.100MHz

Front to Back Ratio:                         33.9dB at 144.100MHz                   33.09dBi at 144.100MHz

Peak Gain:                                        15.28dBi                                           15.28dBi

Peak F/B:                                        33.91dB                                           34.28dB

Bandwidth:                                     1.5MHz below 1.1:1                       1.3MHZ below 1.1:1

Build Dimensions for European Version - If you need 12mm Loop sizing mail me

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           .5135                                               6mm Diameter tube or solid rod

DE1                                       .149                                                      .4365                                               13mm Tube

DE2                                       .309                                                      .4365                                               13mm Tube

D1                                         .545                                                      .479                                               6mm Diameter tube or solid rod

D2                                         .906                                                      .459                                               6mm Diameter tube or solid rod

D3                                        1.356                                                     .4595                                             6mm Diameter tube or solid rod

D4                                        2.019                                                     .4545                                             6mm Diameter tube or solid rod

D5                                        2.785                                                     .4495                                             6mm Diameter tube or solid rod

D6                                        3.608                                                     .445                                               6mm Diameter tube or solid rod

D7                                        4.455                                                     .4385                                             6mm Diameter tube or solid rod

D6                                        5.331                                                     .43                                                 6mm Diameter tube or solid rod

D8                                        6.125                                                     .4275                                             6mm 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

Download the European and UK/USA versions of this antenna in EZNEC format HERE

SWR Plot for the European version of the G0KSC 11el 144MHz LFA Yagi

Build Dimensions for UK/USA Version

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           .5135                                               1/4 inch Diameter tube or solid rod

DE1                                       .149                                                      .4375                                               1/2 inch Tube

DE2                                       .309                                                      .4375                                               1/2 inch Tube

D1                                         .546                                                      .479                                               1/4 inch Diameter tube or solid rod

D2                                         .906                                                      .459                                               1/4 inch Diameter tube or solid rod

D3                                        1.356                                                      .4595                                             1/4 inch Diameter tube or solid rod

D4                                        2.019                                                     .4545                                              1/4 inch Diameter tube or solid rod

D5                                        2.785                                                     .4495                                              1/4 inch Diameter tube or solid rod

D6                                        3.608                                                     .445                                                1/4 inch Diameter tube or solid rod

D7                                        4.455                                                     .4385                                              1/4 inch Diameter tube or solid rod

D6                                        5.331                                                     .43                                                 1/4 inch Diameter tube or solid rod

D8                                        6.125                                                     .4275                                             1/4 inch Diameter tube or solid rod

Notes:

DE1 and DE2 are joined at the ends by either 3/8 tube

Feed point is the centre of DE1

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

Download the European and UK/USA versions of this antenna in EZNEC format HERE

SWR Plot for the UK/USA version of the G0KSC 11el 144MHz LFA Yagi

Antenna Elevation Plot

European version Azimuth Plot

UK/USA Elevation Plot

EME Notes

This antenna makes an excellent EME antenna when configured in a 4 bay stack. Below is the TanT output screen showing that sky temperature is 226.1 Kelvin for this array which is excellent. Not only this, G/T which is the figure of merit used to determine an antennas ability to receive signals is better than any other antenna of this length (-2.29dB).

G/T and Sky Temperature are better than any other antenna of this boom length, period.

4 x 11 element LFA Yagis configured in a 4 Bay array 3.63 metres Vertically and 3.63 metres horizontally

Download the European and UK/USA versions of this antenna in EZNEC format HERE

As always, any questions please ask!

Justin G0KSC