This antenna has been built, tested and used at the RSGB Field Day (2 X Stack) , July 2009. South Portugal being the best result during that contest from thisi fantastic performer. As with all LFA's I publish now, this is a wide-band, low noise antenna and will not shift dramatically in wet weather or when placed near other antennas.
This antenna is particularly good for EME purposes due to it's class leading low noise (Sky Temperature) and 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
- There are two sets of measurements listed below. One uses imperial sizes, the other uses metircsizes. 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
Built by GM3PMB
4 x 9el LFA for 144MHz at WA8HTO
Installed and built by GU8FBO
RSGB Field Day 2009. G0KDV using 2 x 9el LFA Yagis
G8FJGs 9el 144MHz LFA between a 28/50MHz G0KSC DualBand Yagi and a 22el LFA Yagi
4 x 9el 144MHz LFAs at G3MLO (all parts required purchased from this site !!)
The 9el LFA for 144Mhz iinstalled at DL4KUG
A close up shot of the G0KSC 1:1 'Antenna Balun' installed on the 9el LFA
The finished 4 x 9el Array at DL4KUG
There many versions of this antenna below in different element diameters, scroll down!:
Performance European Version UK/USA Version
Forward Gain: 14.15dBi at 144.300MHz 14.13dBi at 144.300MHz
Front to Back Ratio: 24.41dB at 144.300MHz 24.86dBi at 144.300MHz
Peak Gain: 14.2dBi 14.18dBi
Peak F/B: 26.32dB 26.99dB
Bandwidth: 1.4MHz below 1.1:1 1.6MHZ below 1.1:1
Build Dimensions for European Version
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 .515 5mm Diameter tube or solid rod
DE1 .138 .435 13mm Tube
DE2 .306 .435 13mm Tube
D1 .532 .473 5mm Diameter tube or solid rod
D2 .806 .462 5mm Diameter tube or solid rod
D3 1.34 .463 5mm Diameter tube or solid rod
D4 2.052 .4565 5mm Diameter tube or solid rod
D5 2.837 .45 5mm Diameter tube or solid rod
D6 3.659 .44 5mm Diameter tube or solid rod
D7 4.447 .435 5mm 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
Please read the 'how to make the LFA Loop' page here
SWR Plot for the European version of the G0KSC 9el 144MHz LFA Yagi
Build Dimensions for UK/USA Version
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 .515 3/16 inch Diameter tube or solid rod
DE1 .138 .435 1/2 inch Tube
DE2 .306 .435 1/2 inch Tube
D1 .533 .4735 3/16 inch Diameter tube or solid rod
D2 .808 .462 3/16 inch Diameter tube or solid rod
D3 1.34 .463 3/16 inch Diameter tube or solid rod
D4 2.052 .4565 3/16 inch Diameter tube or solid rod
D5 2.837 .45 3/16 inch Diameter tube or solid rod
D6 3.659 .44 3/16 inch Diameter tube or solid rod
D7 4.447 .435 3/16 inch Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by either 3/8 tube
Feed point is the centre of DE1
Please read the 'how to make the LFA Loop' page here
SWR Plot for the UK/USA version of the G0KSC 9el 144MHz LFA Yagi
Performance European Version 4mm
Forward Gain: 13.73dBi at 144.300MHz
Front to Back Ratio: 27.84dB at 144.300MHz
Peak Gain: 13.80dBi
Peak F/B: 28.13dB
Bandwidth: 1.4MHz below 1.1:1
Build Dimensions for European Version with 4mm parasitic elements
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 .5165 4mm Diameter tube or solid rod
DE1 .110 .4365 12mm Tube
DE2 .274 .4365 12mm Tube
D1 .495 .4795 4mm Diameter tube or solid rod
D2 .845 .4665 4mm Diameter tube or solid rod
D3 1.322 .463 4mm Diameter tube or solid rod
D4 1.981 .4565 4mm Diameter tube or solid rod
D5 2.762 .449 4mm Diameter tube or solid rod
D6 3.576 .435 4mm Diameter tube or solid rod
D7 4.366 .4185 4mm Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by either 10mm or 8mm tube. Adjust loop on completion for best SWR.
Feed point is the centre of DE1
Performance UK/USA Version all elements 1/2 inch
Forward Gain: 14.04dBi at 144.300MHz
Front to Back Ratio: 27.78dB at 144.300MHz
Peak Gain: 14.06dBi
Peak F/B: 28.08dB
Bandwidth: 800KHz below 1.1:1
Element Spacing in metres Half element Length in metres Element Notes
Reflector 0 .5075 1/2 inch Diameter tube or solid rod
DE1 .207 .4345 1/2 inch Tube
DE2 .381 .4345 1/2 inch Tube
D1 .564 .4675 1/2 inch Diameter tube or solid rod
D2 .837 .452 1/2 inch Diameter tube or solid rod
D3 1.402 .4495 1/2 inch Diameter tube or solid rod
D4 2.125 .440 1/2 inch Diameter tube or solid rod
D5 2.902 .430 1/2 inch Diameter tube or solid rod
D6 3.747 .415 1/2 inch Diameter tube or solid rod
D7 4.508 .409 1/2 inch Diameter tube or solid rod
Notes:
DE1 and DE2 are joined at the ends by 3/8 inch tube. Adjust loop on completion for best SWR.
Feed point is the centre of DE1
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 236.2 Kelvin for this array which is lower than any other array of this boom length (VE7BQH G/T list, Google search). Not only this, G/T which is the figure of merit used to determine an antennas ability to receive signals is also better than any other antenna of this length (-3.72dB).
G/T and Sky Temperature are better than any other antenna of this boom length, period.
4 x 9 element LFA Yagis configured in a 4 Bay array 3 metres Vertically and 3.1 metres horizontally
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