G0KSC SC0609L 9el 50Mhz Yagi Antenna with a 12 Metre Length BoomThis a long boom 9el Yagi for 50Mhz. It has a boom which is made from a 2 joined pieces 1.25 inch square tube section of 5 metres in length with one addition 5 metre 1.25 inch box section secured beneath the first to in the centre and therefore, bracing the first 2 elements. To extend the boom the 12 metres (additional 2 metres), it is recomended to install a 1 inch box section of 2 metres at the end of the antenna and still mount the antenna at the centre point of the 2 5 metre 1.25 inch box sections. The reason for this is there is additiona weight at the back of the boom due to the concentration of elements. the additional length at the front, acts as a counter balance. No boom support should be required. Dimensions in Metres
Element spacing: - Ref = 0
- Driven = .678
- D1 = .886
- D2 = 2.02
- D3 = 3.724
- D4 = 5.738
- D5 = 7.839
- D6 = 10.312
- D7 = 12.001
Element sizes per element half: - Ref = 1.497
- Driven = 1.475
- D1 = 1.391
- D2 = 1.366
- D3 = 1.34
- D4 = 1.328
- D5 = 1.307
- D6 = 1.304
- D7 = 1.305
Performance figures @ 50.250Mhz: - Froward Gain: 13.92dBi free space
- Front to Back: 33.91dB
- Radiation angle at 10 Metres above ground: 10 degrees
Element diameter: 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 1.25 inch boom as the elements sit high enough above the boom for the boom to have no influence. NOTE: 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. 



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