A Low-Noise 'Urban' 3 element LFA Yagi for 70MHz

Revised March 2010 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 commerical gain exists, express permission of G0KSC must be sort.

EZNEC files for this antenna are on the download page.

If you suffer with noise from living in the city, this is an antenna for you.

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. Note there are no lobes striaght up and down in the Elevation plane.

Note: The loop feedpoint as as per the photo, at the front of the loop nearest the reflector

Please read 'Making the LFA Loop which can be found HERE

2 x 4 element LFAs in stacked config being used in the 4M Trophy 2009 by G0VHF

Performance UK/US version

Gain: 8.66dBi @ 70.20MHz

F/B: 22.44dB @ 70.20MHz

SWR: bandwidth 500KHz 1.3.1

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                              1.058                                            13mm or 1/2 inch

DE1                      .347                          .886                                              13mm or 1/2 inch

DE2                      .678                          .886                                              13mm or 1/2 inch

D1                        1.388                       .9425                                             13mm or 1/2 inch

Performance EU version

Gain: 8.63dBi @ 70.20MHz

F/B: 23.41dB @ 70.20MHz

SWR: bandwidth 500KHz 1.3.1

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                              1.058                                            13mm or 1/2 inch

DE1                      .347                          .885                                              13mm or 1/2 inch

DE2                      .678                          .885                                              13mm or 1/2 inch

D1                        1.388                       .9425                                             13mm or 1/2 inch

Notes:

The loop ends are joined using 3/8 or 10mm tube.

Please read 'Making the LFA Loop which can be found HERE

Azimuth pattern of the UK/US version

Elevation plot of the UK/US version

SWR Plot of the UK/US version

As always, ask if you have any questions and I look forward to working you at field day!

Justin G0KSC