A Low-Noise 'Urban' 9 element LFA Yagi for 50MHz
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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 or just don't want to hear stations behind or to the side of you try this, another low-noise antenna from G0KSC
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 15 metres long, not for every ham in the neighbourhood!
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.
An InnovAntennas supplied 9el 50MHz LFA at EA7KW
The first in a stack of 3 x 9el 50MHz LFA Yagis at W3LPL
The 9el LFA at WA4NJP
The 9el 50MHz LFA (1/2 inch elements) at MI0AYR
The 9 element LFA Yagi for 50MHz how it will look when completed
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
- 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
Performance European Version UK/USA Version
Forward Gain: 14.51dBi at 50.150MHz 14.5dBi at 50.150MHz
Front to Back Ratio: 32.52dB at 50.150MHz 32.53dBi at 50.150MHz
Peak Gain: 14.56dBi 14.54dBi
Peak F/B: 34.59dB 34.86dB
Bandwidth: 600KHz below 1.1:1 600KHZ 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 1.48 10mm Diameter tube or solid rod
DE1 .405 1.225 13mm Tube
DE2 .967 1.225 13mm Tube
D1 1.808 1.387 10mm Diameter tube or solid rod
D2 3.469 1.352 10mm Diameter tube or solid rod
D3 5.499 1.327 10mm Diameter tube or solid rod
D4 7.801 1.306 10mm Diameter tube or solid rod
D5 10.238 1.283 10mm Diameter tube or solid rod
D6 12.771 1.249 10mm Diameter tube or solid rod
D7 15.016 1.247 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
SWR Plot for the European version of the G0KSC 9el 50MHz LFA Yagi
Build Dimensions for UK/USA Version
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 1.481 3/8 inch Diameter tube or solid rod
DE1 .405 1.225 1/2 inch Tube
DE2 .967 1.225 1/2 inch Tube
D1 1.809 1.388 3/8 inch Diameter tube or solid rod
D2 3.469 1.353 3/8 inch Diameter tube or solid rod
D3 5.499 1.328 3/8 inch Diameter tube or solid rod
D4 7.801 1.307 3/8 inch Diameter tube or solid rod
D5 10.238 1.284 3/8 inch Diameter tube or solid rod
D6 12.771 1.25 3/8 inch Diameter tube or solid rod
D7 15.016 1.248 3/8 inch Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by 3/8 inch tube
Feed point is the centre of DE1
Build Dimensions for UK/USA Version with all 1/2 inch elements
Performance
Forward Gain: 14.63dBi at 50.150MHz
Front to Back Ratio: 38.38dB at 50.150MHz
Peak Gain: 14.65dBi
Peak F/B: 38.92dB
Bandwidth: 500KHz below 1.1:1
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 1.477 1/2 inch Diameter tube or solid rod
DE1 .406 1.226 1/2 inch Tube
DE2 .970 1.226 1/2 inch Tube
D1 1.801 1.381 1/2 inch Diameter tube or solid rod
D2 3.476 1.3435 1/2 inch Diameter tube or solid rod
D3 5.537 1.319 1/2 inch Diameter tube or solid rod
D4 7.826 1.300 1/2 inch Diameter tube or solid rod
D5 10.230 1.280 1/2 inch Diameter tube or solid rod
D6 12.743 1.248 1/2 inch Diameter tube or solid rod
D7 15.018 1.2465 1/2 inch Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by 3/8 inch tube
Feed point is the centre of DE1
SWR Plot for the UK/USA version of the G0KSC 9el 50MHz LFA Yagi
Antenna Elevation Plot
European version Azimuth Plot
UK/USA Elevation Plot
As always, any questions please ask!
Justin G0KSC