ZS6NK installs a much shorter 8el 50MHz LFA Yagi along side his 16m long 11el M2 for comparison tests

I met Paul at the G3WOS 50MHz BBQ last year and already Paul was contemplating changing to LFA Yagis but for his own piece of mind, he wanted to do some comparison tests and has the means to do so.

The first tests conducted by Paul included a switch from a DL6WU design for 70MHz to an LFA. in this instance, both antennas were similar in length and therefore, the differences where marked with signals barely detectable on the DL6WU being Q5 and several S units up on the LFA.

For 50MHz however, Paul wanted to switch to a smaller antenna and hence a much more difficult test would result as the LFA would be compared to a much longer antenna. Paul built and compares an 8el 50MHz LFA Yagi at 12.5m long with an 11el M2 at 16m long on separate towers at the same height.

The first picture above was taken after the first set of F/B tests. I asked Paul to take a photo of the antennas and send it to me after the M2 was at least 3S points down in F/B on the LFA. With most LFAs the F/B is in excess of 30dB but this particular design is around 26dB F/B and so in standard form, should be comparable to the M2 in terms of F/B performance and while I expect the T matching system on the M2 to reduce gain a little and F/B by 6-12dB, I did not expect the estimated 18dB or more reduction.

The picture told the story; the boom on the M2 was not straight and this would cause a drop in F/B. Paul took my advice and adjusted the M2 boom which did improve the F/B a little and therefore a more comparable test could be made.

For those doubters the recorded results made, tell the LFA story. These were all conducted AFTER the boom on the M2 was straightened and while comparisons could not be made with the two antennas pointing through each other (for obvious reasons), they were made when they where both were pointing in the same direction and as can be seen, marked differences between the antennas exist. Below is a back-ground noise comparison between the two antennas when pointing directly north. First is the 11el and then mid way through, the LFA is switched in line.

http://www.g0ksc.co.uk/North.mp3

The step down in noise is quite apparent and you do not need to strain your ears to be able to hear when the antennas are switched. However,  is it a dummy load antenna that is being switched in line? Is it just a reduction in all received signals which is being seen here which would mean no benefit would be seen from the LFA?

The next comparison is that of the receiving of the JY6ZZ beacon via TEP in South Africa. Again the first part of this audio is the 11el and the latter part is the LFA Yagi.

http://www.g0ksc.co.uk/jy6zz.mp3

You maybe forgiven for thinking that you are just listening to white noise again, that is until the LFA is selected!

This latest test by ZS6NK is just another in a long line of tests by hams and commercial entities of the LFA Yagi against traditional Yagis. Not just in an electromagnetic form, but as a built antenna and it is the result of the carefully selected (and tested) materials in use, in addition to the many hours spent on the electromagnetic design which contribute to the exceptional results seen with the LFA.

Above the WSJT plots for both the LFA and M2 as rotated and switched from one to the other. Circled in Yellow are the M2 noise levels, circled in red, the noise levels on the LFA

If you want to hear more, you need a low noise antenna, whatever the band you are on. This is why so many EME fans are now switching to the LFA Yagi. Do you want to hear and work the weak?

So, what are you waiting for?

Justin G0KSC