GB2GP has three towers at 60, 80 and 100ft. For 28MHz we currently have a 3 element yagi at 100ft, a 5 element yagi at 80ft, which could be moved to the 60ft tower if needed. There is no easy way to move the big yagi to 100ft.
The HFTA analysis presented in the gallery below compares these antennas against a flat earth model. I have assumed the following beam headings:
JA - 30 Deg
EU - 80 Deg
AF - 170 Deg
NA -300 Deg
SA - 235 Deg
AS - 80 Deg
Click through the gallery and let me know which height would would choose and why!
My conclusions at 28Mhz are:
1) Gain is more important than tower height at this site on this band.
2) The 5 element at 28MHz has a better figure of merit at 60 ft in most directions as it's gain doesn't fall away at medium arrival angles compared to higher antennas.
3) The take of angle to the EU is quite a lot more than 5 degrees, maybe EU isn't DX?
4) My on air experience is that the 3 el at 100 ft is able to open the band. I guess this is because the arrival angle is low and the combination of 100ft tower and the slope works to our advantage.
Please use the comments below or tag me in Twitter!
1) Gain is more important than tower height at this site on this band.
2) The 5 element at 28MHz has a better figure of merit at 60 ft in most directions as it's gain doesn't fall away at medium arrival angles compared to higher antennas.
3) The take of angle to the EU is quite a lot more than 5 degrees, maybe EU isn't DX?
4) My on air experience is that the 3 el at 100 ft is able to open the band. I guess this is because the arrival angle is low and the combination of 100ft tower and the slope works to our advantage.
Please use the comments below or tag me in Twitter!
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