Google Translate

×

Message

EU e-Privacy Directive

This website uses cookies to manage authentication, navigation, and other functions. By using our website, you agree that we can place these types of cookies on your device.

View e-Privacy Directive Documents

A short 5 element LFA Yagi for 50MHz with a 4.4mtr boom

Revised 9th December 2009 V1.1

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 commercial 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 50MHz 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:

 

3 x 5el (yes, 3!!) 4.4m boom 50MHz LFAs at G8VR installed by G8VR and G0KSC April 2011

 

2 x 4.4m long 5el 50MHz LFAs at G3OIL for summer 2011

 

The 4.4m G0KSC 5el 50MHz LFA at ON6ZG

 

The 4.4m 5el LFA at G0LFF

 

'Have done the final tweaks and now have SWR 1.0 to 1 @50mhz and 1.1 to 1 @50.6mhz....'

'...First impressions are good with a much lower hash noise threshold and pointing at the setting

moon received decode on 1st lobe within minutes :-) ...'

G0LFF

2 x 4.4M long 50MHz LFAs installed for Summer 2010 at G0KSC

 

Performance

Gain: 10.63dBi @ 50.150MHz

F/B: 29.33dB @ 50.150MHz

Peak Gain: 10.64dBi

Peak F/B: 34.57dB

SWR: Below 1.1.1 from 50MHz to 50.600MHz

Stacking Distances:

Retain good Pattern: 4.7M @ 13.46dBi for 2 antennas

Highest gain: 5.3M @ 13.62dBi for 2 antennas

 

Construction

Download the EZNEC files HERE

For full details of how to make the LFA, read here: http://www.g0ksc.co.uk/making-the-lfa-loop.html

Antenna Dimensions

Spacing                      Half Element Size  in Metres              Element Diameter

Reflector                0                              1.483                                             10mm or 3/8 inch

DE1                      .314                          1.244    (1.242 for 12mm Tube)        13mm or 1/2 inch

DE2                      .866                          1.244    (1.242 for 12mm Tube)        13mm or 1/2 inch

D1                       1.381                         1.402                                             10mm or 3/8 inch

D2                       2.675                         1.357                                             10mm or 3/8 inch

D3                       4.354                         1.298                                             10mm or 3/8 inch

 

The ends of DE1 and DE2 are connected together with 10mm or 3/8 inch tube. 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 the swr graph is correct and confirmed within nec4 and through building this antenna.

 

 

 

 

 

Impressive - The G0KSC 2 x 5el Stack performance at 12m up where it is located at G0KSC

 

Any questions, please ask!

 

Justin G0KSC

 
 
 
 

Google Translate