Ron, G8FJG proves the LFA low noise characteristic by building one and comparing with his existing DK7ZB 70cms Yagi.
Ron built a DK7ZB 16el 70cms Yagi some time back and was very pleased with the results. However, after reading the LFA story within DUBUS magazine, Ron decided to build a 70cms LFA. There were no publsihed 70cms designs so I sent Ron the dimensions for one of my test antennas I was going to build (now built and tested). The LFA was a 19el version so is a little longer than the DK7ZB it was going to be compared with although the LFA would be more than 1 metres lower than the DK7ZB on the tower. Additionally, the excellent DK7ZB antenna is tuned for maximum gain and therefore, (in theory at least) the additional gain on the 19el LFA would be less than 1dB.
The fact is when both antennas are on the tower and wound up, a big difference in noise level can be heard between the two antennas and as a result, the desired signal seems much louder. 'I asked my wife Jan to tell me which one sounded stronger' said Ron G8FJG. 'The beams were pointing at PI7CIS and I switched between Antenna 'A' and Antenna 'B'. She correctly picked the G0KSC LFA on the first switch over without seeing the S meter. and this with the LFA being closer to the ground and man-made noise than the DK7ZB!.' he went on to say.
Spectrum Scope image showing the noise level between the DK7ZB and the G0KSC LFA
right click the image above and click 'view image' to see the full size spectrum scope image file
The above image shows the noise level between the G0KSC LFA and the DK7ZB 70coms Yagi. The image is small in order to fit on this page. However, in the latter half of the scale, Ron switched between antennas each minute in order that the differences would coinside with the white minute markers which run top to bottom. The LFA can be clearly seen as low noise by the darker stripes running from the top to bottom of the page.
This first LFA being used by G0KSC and G8FJG will be published within the next issue of DUBUS magazine. Don't miss it!