An alternative to the 6M7JHV antenna for 6m / 50MHz
Subjective noise thoughts
Reducing the impact of local noise was the primary goal of going to all the effort and cost of building a pair of new antennas. However, ascertaining whether the LFAs are better than the 6M7JHVs is far from a logical task as local noise sources vary so considerably.
Before swapping the stacks I measured the noise level using WSJT at all hours of the day through 360 degrees with an aim of comparing before and after. More on this when I have undertaken the analysis.
However, in the mean time I do have some positive news. When I pointed my antennas at 90 degrees, they are pointing down all the houses in my road and thus is the noisiest direction I have (barring ad hoc arcing). For all this summer this noise registered s2 to s3 on my transceiver's S-meter. Looking at this noise today, I can say that the S-meter does not now move at all. Of course, I will need to monitor this over an extended period of time to be sure this result is real (I really do hope that it is!).
The reduced noise level @ 90 degrees
I have found on numerous occasions in the past that when I do get severe interference it has originated in close by houses. Therefore, I have assumed that this 'aggregate' S2 to S3 of noise from 90 degrees is the sum of all the noise of all the electronic devices in houses down the road. Therefore, using an antenna with much better front lobe suppression - which the LFAs have - -30.8dB could significantly reduce this interference.
The plot below shows the elevation performance of the 6M7JHV and the LFA2 and graphically shows the difference in the size of the forward facing lobes. Don't forget that the lobes shown in the plot are mirrored below the antenna as well and point straight to my neighbours houses.
6M7JHV (red) v LFA2 design in elevation at 20 metres
At the moment it looks to me that theory coincides with practice - I hope it continues.
When I added elevation I can see noise reductions of 10dB plus! Note that by elevating by only 15 degrees reduces background noise by 2dB - that is a lot!
