G0KSC - Simple to build, High Performance Yagi and Quad Antennas - Home of the LFA Yagi

144MHz LFA Yagis

Low Noise LFA Yagis designed by G0KSC free to build for personal use.

70cms LFA Yagis

Twin-Boom G0KSC Quads

G0KSC Twin-Boom Quads

G0KSC Custom Dish feeds - Above installation @ HB9Q

Custom low-noise dish feeds

G0KSC Custom Dish Feeds

Above installation @ HB9Q

Read Time: 2 - 4 minutes

A 3 element LFA Yagi for 24MHz with a 3.9mtr boom

This is a high-gain, wideband LFA (Loop Fed Array) Yagi which covers 24.890 - 24.980MHz with an SWR of less than1.1:1. It has options with both UK/USA and European sized tube and has a 3 section taper.

This Antenna has been modelled using NEC4 and confirmed by FEKO. This is thousands of dollars of the very latest antenna design software available and the results are highly accurate. When loading into your software, you will see similar SWR but not the same. Please do not alter the model, build to these dimensions for the best results.

Contact me if you are unsure what correction (if any) you require for the element holders/stand-offs you will use or any other questions you may have or require different element diameter.

M0CTR installed a 3el 24MHz LFA

'Hi Justin,

Well here we are with the 12m beam, I apologies for the quality of the pics, the best ones are actually the beam in the air but it was an awful day yesterday with fine drizzle and that got on the lens, Some better ones to follow I promise. The beam works and tuned a treat, first contact was into Paraguay which is not a common contact on 12 for me, cream of the days was HK0 San Andreas and province, in Central America, working split and with quite a pile up, that's a new band slot for me, also worked into Brazil, as well as several contacts to N. America. It seems to give a very quite reception and the results are very encouraging considering the SFI was below 80 again.

The dimensions were spot on for a perfect SWR...'

'...The LFA worked a treat and I followed your advise from the web site which worked perfectly..'

Andy M0CTR

Antenna Layout and Construction:

Performance

8.51dBi @ 24.920MHz

21.17dB @ 24.920MHz

SWR: Below 1.1:1 from 24.89MHz to 24.980MHz

Stacking:

Distance: 5m

Gain: 10.6dBi (15.87 at 15m above real ground)

F/B: 21.76

Construction details:

Refer to the above drawings

Antenna Dimensions for UK/USA and European sized tubing

Taper: Mid Section, 5/8 inch or 16mm tube (total length 2.40m). Outer section 1/2 inch or 13mm tube (4.40m). End sections as per below schedule and in 3/8 inch or 10mm.

Spacing End Section Length (All below sizes in Metres)

Reflector 0 .885

DE1 .819 0.311 - FEEDPOINT

DE2 1.914 0.311

D1 3.912 0.562

Adjust loop width for best SWR upon completion. Fit antenna with a 1:1 balun

Polar Plots