G0KSC SC144011L 11el 144Mhz Yagi Antenna with a 6.8 Metre Length Boom
This is a good wide band Yagi optimised for 144 to 144.600Mz. It has a mid-sized length boom of 6.8 metres and therefore can be made from a single piece 1.25 inch square tube section. Boom Support will be required with by guy wire or an additional 1.25 inch boom length bolted to the bottom of the main boom and covering 4 metres (2 metres either side of the boom centre.
Remember, this is a very wide band Yagi although it only has 11 elements it provides good forward gain. Performance of this antenna is very good with maximised radiation efficiency and very low loss. Take a look at the images below.
The SC14411L at WB9WOZ - Bruce has an 18el LFA for 430MHz directly below it
Dimensions in Metres
- Ref = 0
- Driven = .374
- D1 = .535
- D2 = 1.010
- D3 = 1.707
- D4 = 2.503
- D5 = 3.361
- D6 = 4.235
- D7 = 5.124
- D8 = 6.050
- D9 = 6.795
Element sizes per element half:
- Ref = .508
- Driven = .506
- D1 = .478
- D2 = .4635
- D3 = .452
- D4 = .4445
- D5 = .437
- D6 = .433
- D7 = .4265
- D8 = .4235
- D9 = .4355
Performance figures @ 144.300Mhz:
- Froward Gain: 15.78dBi free space
- Front to Back: 24.01dB
- Radiation angle at 10 Metres above ground: 3 degrees
Each element is made out of single piece 1/2 inch (12.7mm) aluminum tubing Each element half length needs to be doubled in order to gain your total element size. No difference is length needs to be calculated for the 1inch or 1.25 inch boom as the elements sit high enough above the boom for the boom to have no influence.
You can build this antenna with 13mm diameter tubing using the same parameters above. Slightly higher front to back ratio and forward gain will be seen along with a narrower SWR curve.
For construction information see 'G0KSC insulators' and the UKSMG article from the main menu on the home page.
Antenna layout, how it will look
Super clean, low-noise pattern
A Symmetrical, low-noise elevation plot too
SWR Plot nice and low.
Enjoy the antenna and please send photos!