A Low-Noise 'Urban' 7 element LFA Yagi for 144MHz
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, this is another low-noise antenna from G0KSC
This one is really nice and compact, has good bandwdith (1MHz 1.1:1) and yet has maintained an excellent pattern at the same time. Stacked in 4, you would not be unhappy with this very low-noise LFA for EME working. This antenna will be particularly good for EME purposes due to it's very low noise (Sky Temperature) and excellent G/T figures. See the bottom of this page for more information.
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. Do not confuse your version of EZNEC with nec version. 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
The 7el 144MHz LFA installed at K3UAZ completed with G0KSC Antenna Balun above the boom
The 7el 2m LFA by MW0CXH - Below is the SC6-4-8D Dualband G0KSC (4m/6m) Yagi
Peter comments:
Note: performance figures centred on 144.100MHz the centre EME frequency
Performance European Version UK/USA Version
Forward Gain: 12.83dBi at 144.100MHz 12.81dBi at 144.100MHz
Front to Back Ratio: 21.21dB at 144.100MHz 21.33dBi at 144.100MHz
Peak Gain: 12.88dBi 12.87dBi
Peak F/B: 23.46dB 23.67dB
Bandwidth: 1MHz below 1.1:1 1MHZ 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 .52 10mm Diameter tube or solid rod
DE1 .088 .435 13mm Tube
DE2 .261 .435 13mm Tube
D1 .399 .476 10mm Diameter tube or solid rod
D2 .809 .461 10mm Diameter tube or solid rod
D3 1.471 .449 10mm Diameter tube or solid rod
D4 2.2 .438 10mm Diameter tube or solid rod
D5 2.894 .434 10mm Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by either 10mm tube. Feed point is the centre of DE1
SWR Plot for the European version of the G0KSC 7el 144MHz LFA Yagi
Build Dimensions for UK/USA Version
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 .52 3/8 Inch Diameter tube or solid rod
DE1 .088 .434 1/2 inch Tube
DE2 .261 .434 1/2 inch Tube
D1 .401 .475 3/8 inch Diameter tube or solid rod
D2 .809 .461 3/8 inch Diameter tube or solid rod
D3 1.471 .449 3/8 inch Diameter tube or solid rod
D4 2.2 .438 3/8 inch Diameter tube or solid rod
D5 2.894 .434 3/8 inch Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by either 3/8inch tube. Feed point is the centre of DE1
SWR Plot for the European version of the G0KSC 7el 144MHz LFA Yagi
Antenna Elevation Plot
European version Azimuth Plot
UK/USA Azimuth Plot
EME Notes
This antenna makes an excellent EME antenna when configured in a 4 bay stack. Below is the TanT output screen showing that sky temperature is 237.3 Kelvin. There is no other array this short on the VE7BQH list. However, the sky temperature is lower on this array than many of the longer arrays listed (VE7BQH G/T list, Google search).
There are no antennas as short as this on the VE7BQH G/T list. However, this array still outperforms longer arrays in all respects
4 x 7 element LFA Yagis configured in a 4 Bay array and showing current distribution. 2.25 metres Vertically and 2.975 metres horizontally. Optimum spacing still to be defined
As always, any questions please ask!
Justin G0KSC