A Low-Noise 'Urban' 8 element LFA Yagi for 144MHz

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 badnwdith (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:

• 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 your version of EZNEC with nec version. EZNEC uses nec2 by default.
• 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

4 x 8el LFA at IV3MUR for EME

VE7XDT installing his bay of 4 x 8el 144MHz LFA Yagis

The completed VE7XDT Array - more photos of this array at the bottom of the page

'Your antennae are PERFECT!!! We calibrated my MFK 269 first. After that we tuned the 4 antennae - all came

with in 1/2mm accuracy in dimensions!!! There is 250KHz zone with SWR being 1.0:1 - amazing!!! Lionel (VE7BQH)

was impressed .'

- VE7XDT

The 8el LFA at IK8YSW with G0KSC Antenna Balun installed (boom top) pic taken at IARU 2010 contest 

'Hi Justin, here some pictures of my fresh 144 MHz 8 el LFA during IARU VHF reg1 contest, also a picture of swr meter...
The antenna receives very little noise, it's very interesting !!

Thanks for this nice designed antenna .

73 de Errico - IK8YSW'

 

IK8YSW shows his impressive SWR on the above antenna during the contest

Jose EA2FL installs his 8el 2M LFA on top of his tower

The 8el 2M LFA at EI7BA

IV3MUR with his 8el 2m LFA installed with elevation for EME. The reflector is just 50cms from ground!

One of IV3MURs EME QSOs with this single 8el LFA. Note the -17 signal strength!

Note: performance figures centred on 144.100MHz the centre EME frequency

Performance European Version                             UK/USA Version

Forward Gain:                                 13.29dBi at 144.100MHz                 13.32dBi at 144.100MHz

Front to Back Ratio:                        25.69dB at 144.100MHz                 25.76dBi at 144.100MHz

Peak Gain:                                        13.35dBi                                           13.36dBi

Peak F/B:                                           27.85dB                                           28.36dB

Bandwidth:                                       1MHz below 1.1:1                       1MHZ below 1.1:1

Build Dimensions for European Version -  12mm Loop sizing is 434mm per half - always adjust for best SWR

Note: Dimentions  are the same for both antennas, only the tube diameter changes

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           .515                                               1/4 inch OR 6mm mm Diameter tube or solid rod

DE1                                       .127                                                      .436                                               1/2 inch OR 13mm Tube

DE2                                       .29                                                        .436                                               1/2 inch OR 13mm Tube

D1                                         .46                                                        .480   (.4805 for UK/USA Version) 1/4 inch OR 6mm Diameter tube or solid rod

D2                                         .846                                                      .467                                               1/4 inch OR 6mm Diameter tube or solid rod

D3                                        1.466                                                     .457                                               1/4 inch OR 6mm Diameter tube or solid rod

D4                                        2.187                                                     .447                                               1/4 inch OR 6mm Diameter tube or solid rod

D5                                        2.973                                                     .434                                               1/4 inch OR 6mm Diameter tube or solid rod

D6                                        3.729                                                     .42                                                 1/4 inch OR 6mm Diameter tube or solid rod

Notes:

DE1 and DE2 are joined at the ends by either 10mm tube (when 13mm main sections used) or3/8 inch tube (when 1/2 inch main sections are used).

Feed point is the centre of DE1

SWR Plot for the European version of the G0KSC 8el 144MHz LFA Yagi

SWR Plot for the UK/USA version of the G0KSC 8el 144MHz LFA Yagi

Antenna Elevation Plot

European version Azimuth Plot

UK/USA Azimuth 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 236.2 Kelvin for this array which is lower than any other array of this boom length (VE7BQH G/T list, Google search). Not only this, G/T which is the figure of merit used to determine an antennas ability to receive signals is also better than any other antenna of this length (-3.72dB).

There are no antennas as short as this on the VE7BQH G/T list. However, this array still outperforms longer arrays in all respects

4 x 8 element LFA Yagis configured in a 4 Bay array 2.4 metres Vertically and 2.6 metres horizontally. Optimum spacing still to be defined

The VE7XDT EME Array pointed to the stars...

At the moon - The VE7XDT array ready for action

As always, any questions please ask!

Justin G0KSC

A Low-Noise 'Urban' 12 element LFA Yagi for 50MHz

Revised 24th August 2009 V1.0

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.

 

I am not sure too many of these will be built due to size but I guess I maybe surprised. This is truley an excellent performer. If you build one let me know.

Like the 9, 10 and 11 element version before it, this antenna has been designed with light-weight in mind and optimum performance through single piece elements. It has all the common attributes of an LFA Yagi, Flat SWR,Excellent Gain, fantastic Front to Back ratio and suppressed unwanted lobes.

A True DX'ers antenna and at over 22 metres long, not for every ham in the neighbourhood! However, this antenna does have a massive .3dB advantage over the smaller 11 element version and at these levels of gain, that can make quite a difference.

Both European and UK/USA versions are available. Build and construction details are below and EZNEC files are available for download on the download page.

 

 

The 12 element LFA Yagi for 50MHz. How it will look when completed

 

Elevation plot as presented in 4nec2

 

Supper clean Azimuth Plot shown by 4nec2

 

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 EZNEC with the NEC engine. EZNEC uses nec2 by default
• 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
• Please do not alter segmentation or try to 'tune' the antenna unless you have nec4 or better. SWR will not read true within anything else

Download both the European and UK/USA EZNEC files HERE

Performance European Version                             UK/USA Version

Forward Gain:                                   15.83dBi at 50.150MHz                 15.82dBi at 50.150MHz

Front to Back Ratio:                           27.22dB at 50.150MHz                  27.72dBi at 50.150MHz

Peak Gain:                                       15.84dBi                                           15.83dBi

Peak F/B:                                          32.43dB                                           32.72dB

Bandwidth:                                       500KHz below 1.1:1                       500KHZ 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                                                             1.479                                               10mm Diameter tube or solid rod

DE1                                       .409                                                         1.231                                               13mm Tube

DE2                                       .972                                                         1.231                                               13mm Tube

D1                                         1.734                                                       1.392                                               10mm Diameter tube or solid rod

D2                                         3.359                                                       1.358                                               10mm Diameter tube or solid rod

D3                                         5.29                                                         1.338                                               10mm Diameter tube or solid rod

D4                                         7.63                                                         1.316                                               10mm Diameter tube or solid rod

D5                                         9.938                                                       1.303                                               10mm Diameter tube or solid rod

D6                                         12.422                                                     1.287                                               10mm Diameter tube or solid rod

D7                                         15.028                                                     1.264                                               10mm Diameter tube or solid rod

D8                                         17.494                                                     1.249                                               10mm Diameter tube or solid rod

D9                                         20.135                                                     1.213                                               10mm Diameter tube or solid rod

D10                                       22.481                                                     1.205                                               10mm Diameter tube or solid rod

Notes:

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

Feed point is the centre of DE1

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

Download both the European and UK/USA EZNEC files HERE

SWR Plot for the European version of the G0KSC 12el 50MHz LFA Yagi

 

Download both the European and UK/USA EZNEC files HERE

 

Build Dimensions for UK/USA Version

Element                             Spacing in metres Half element Length in metres            Element Notes

Reflector                                0                                                           1.486                                               3/8 inch Diameter tube or solid rod

DE1                                       .409                                                      1.23                                                1/2 inch Tube

DE2                                       .972                                                      1.23                                                1/2 inch Tube

D1                                         1.734                                                    1.387                                               3/8 inch Diameter tube or solid rod

D2                                         3.359                                                    1.357                                               3/8 inch Diameter tube or solid rod

D3                                         5.29                                                      1.335                                               3/8 inch Diameter tube or solid rod

D4                                         7.63                                                      1.314                                               3/8 inch Diameter tube or solid rod

D5                                        9.938                                                     1.3                                                   3/8 inch Diameter tube or solid rod

D6                                        12.422                                                   1.286                                               3/8 inch Diameter tube or solid rod

D7                                        15.028                                                   1.275                                               3/8 inch Diameter tube or solid rod

D8                                        17.494                                                   1.254                                               3/8 inch Diameter tube or solid rod

D9                                        20.135                                                   1.239                                               3/8 inch Diameter tube or solid rod

D10                                      22.481                                                   1.206                                               3/8 inch Diameter tube of solid rod

Notes:

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

Feed point is the centre of DE1

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

SWR Plot for the UK/USA version of the G0KSC 12el 50MHz LFA Yagi

 

Antenna Elevation Plot

 

European version Azimuth Plot

 

UK/USA Elevation Plot

 

Download both the European and UK/USA EZNEC files HERE

As always, any questions please ask!

 

Justin G0KSC