A Low-Noise 'Urban' 11 element Plus2 LFA Yagi for 144MHz
Premium commercial versions of this antenna at Innovantennas
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.
The new LFA Plus2 range includes an additional 2 reflectors which are used in order to maintain pattern stability throughout the 1MHz coverage (144-145MHz).This is the ultimate in 2m VHF performance today, the new LFA Plus2 is the one to beat showing flat SWR, pattern stability throughout and better sky temperature and G/T figures than any other Yagi of the same boom length (VE7BQH list).
Currently these antennas are available in METRIC SIZES ONLY. Imperial will be launched at a later date.
As with ALL LFAs this antenna requires no matching, it has a 50 Ohm input impedance.
2 x 11el Plus2 LFA Yagis at OZ1CT (G0KSC 6m/4m dual bander on other side of the tower)
The VK3VG 2 x 11el Plus2 2M LFA Yagi
4nec2 (with nec4 engine) Elevation plot of the 11el Plus2 LFA Yagi
The 11el Plus2 Azimuth plot from the 4nec2 antenna modelling package
SWR as presented in the 4nec2 antenna modelling package using nec4.1 Double Precision calculation engine
How the antenna will look when built
- 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
Performance European Version
Forward Gain: 15.26dBi at 144.300MHz
Front to Back Ratio: 25.26dB at 144.300MHz
Peak Gain: 15.27dBi
Peak F/B: 25.74dB
Bandwidth: 144-145MHz below 1.1:1
Build Dimensions for European Version - mail me if you need 12 or 13mm tube driven loop sizing
Element Spacing (m) Half element Length (m) Element Notes
Plus2 Rear Reflectors 0 .508 above and below loop by 225mm 8mm tube
Reflector .192 .514 8mm Diameter tube or solid rod
DE1 .354 .444 10mm Tube
DE2 .519 .444 10mm Tube (feedpoint)
D1 .750 .478 8mm Diameter tube or solid rod
D2 1.214 .461 8mm Diameter tube or solid rod
D3 1.625 .449 8mm Diameter tube or solid rod
D4 2.167 .453 8mm Diameter tube or solid rod
D5 2.896 .447 8mm Diameter tube or solid rod
D6 3.688 .441 8mm Diameter tube or solid rod
D7 4.526 .436 8mm Diameter tube or solid rod
D8 5.435 .424 8mm Diameter tube or solid rod
D9 6.226 .425 8mm Diameter tube or solid rod
DE1 and DE2 are joined at the ends by 8mm tube
Feed point is the centre of DE2
As always, any questions please ask!