[VHFcontesting] [VHF] LFA Yagi Discussion

[James Duffey]

Les - The low noise advantage quoted for these antennas is due to the low sidelobes in the patttern. They will not do anything to reduce the noise seen by the main lobe of the antenna. 

I am not sure what antennas you are running now, but look at the patterns of your antennas and the patterns of the Loop Fed Yagis and see how much different they are. If the sidelobes on your antenna are substantially greater than the Loop Fed Yagi, you might see some advantage. 

I say might, because the sidelobes of an antenna are affected by materials in their fields, and if close stacked, by the other antennas in the stack. I suspect that the Loop Fed Yagis would perform similarly to the antennas you already have in the environment you have them in.

The Loop Fed Yagis are not unique in the low sidelobe aspect. YU7EF and DK7ZB have also designed Yagis with low sidelobes and you might find it interesting to compare the patterns of antennas that have the length you are interested in. Although the patterns will be different in details, they all have pretty low sidelobes and good, if not great, front to back.

Good modern Yagis from many commercial companies are designed to have low sidelobes as well.

In short, I doubt that you would see significant improvement in signal to noise ratio in going from your current antennas to the new antennas, unless the antennas you have are pretty bad. Going to a longer antenna may help, if you can fit one in it, but if I recall correctly you have pretty much as long an antenna as you can swing.

The increased bandwidth won't help much, most antennas tuned for the weak signal end of the band are wide enough. 

Let us know how things work out. - Duffey 


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KK6MC
James Duffey
Cedar Crest NM