• G0KSC designed 3el, 40M & 6el 20M (Force 12)

    This antenna uses the G0KSC OP-DES design on both 40m and 20m to provide full-band coverage on each.

  • 6 x 7el WOS 50MHz LFA Yagi

    175' fully rotating tower and 6 x 7el 50MHz WOS LFA Yagis at W7EW

  • 3 el 24MHz LFA Yagi by InnovAntennas

    Serious low-noise performance for the HF bands too!

  • 4 x 6el 50MHz LFA Yagis @ DL5WP

    Those that do their research and want low noise Yagis choose G0KSC designs!

  • 4 x 11el 144MHz LFA's @ F3EGA

    Excellent G/T figure antenna array ensuring F3EGA can hear and be heard!

  • G0KSC Monoband 14MHz Log Periodic

    With a boom of just 2m and F/B in excess of 20dB including full-band coverage, this is a super-compact Field day antenna!

  • 4 x 24el 432MHz LFA @ PA2V

    PA2V selected G0KSC LFAs (built by InnovAntennas) when he wanted the very best in EME performance!

  • 4el 27MHz LFA Yagi by InnovAntennas

    A 4 element 27MHz LFA by InnovAntennas. The LFA can handle 20KW plus and does for many radio stations, commerical and hobby!

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You read all sorts of stuff around the Internet these days since the LFA made such an impact on Yagi design. On one site you will read 'you don't need fancy loops to make a Yagi'. Well that is right, you don't if you want the same old performance that has been around for decades. The same author suggests the LFA is not 50Ω and is in fact much lower. What he perhaps still does not have a grasp of is what this 50Ω feed is all about, what constitutes a 50Ω Yagi? From my point of view a 50Ω Yagi is one that comes out of the optimiser and needs nothing attached to it to allow 50Ω coax to be connected to a 50Ω feed point. No matching devices, traps, coils or odd impedance coax cables all of which could impact the final performance of the antenna in one way or another.

I read another recently where the self-proclaimed professional designer states 'You will be amazed by their performance' and links to a mocked VE7BQH list showing performance compared with other antennas and as well as being extremely narrow band (meaning the antenna will be unstable around other antennas and in wet weather), all other parameters are very average at best.

Despite the attempts by a few to undermine, the serious and well educated continue to switch to the G0KSC LFA Yagi and enjoy the associated Benefits. Many have done so until now and more recently,  Joe Taylor, K1JT asked me to design an LFA Yagi array for the Princeton University in the USA which is to be used for Radio Astronomy. Also, HB9Q has a very large dish array used for EME applications. The feed system consisted of 4 x 3el DK7ZB Yagis and they wanted to replace these with LFAs. I explained that for best and continued performance across the required range, 3 elements on the boom length currently used is too few so suggested 4 elements per boom would be needed. We implemented the design and the antennas were installed with the results being presented below.

Another interesting point which I have long presented is that despite any loop feed being installed on a Yagi, the loop is not self-balancing, not in all real-world conditions in any case. The importance of which is very much highlighted in the below summary of events (ferrite cores on the coax) and I will cover this subject in more detail in a future issue of DUBUS magazine.

Remember, G0KSC designed antennas are optimised for Signal to Noise ratio, the same as any other part of the receiver. The naive continue to design narrow-band, 'Gain, Gain, Gain' focused antennas and I am sure will remain blinkered and continue to do so for many years to come....

The new LFA feed point array at HB9Q

 

Hi Justin

I didn't wrote this email before because I was waiting receive the ferrite cores to install on the coax line, after a long discussion with Dan we conclude than the replacement of our feed based in your LFA antennas was a good move:

1- First definitive we find a better SWR on our pass band, the antennas match almost perfect in 144.1, after correct some minor errors on the coax termination SWR was 1.2:1 or better

2- That initial test was done without any kind of RF choke on the coax termination, today we install 6 ferrites (same as you recommend) in each antenna and we had no variation on the SWR, very good.

3- Now the interesting part, initial test show 2dB lower noise compared with the original feed system and the initial sun noise measurements show also aprox 1 to 2dB more sun noise, never the less measure sun noise in 2m is not really accurate but give an idea how system perform.

4- We compare all our measurements with our 8 x19el M2 yagis and with the records we have with the old feed and looks like we confirm 1 to 2dB more sun noise with the LFA feed!! Great!!

5- What was really nice is we had less birdies on out pass band and definitive our noise level is lower, both channels (Horizontal and Vertical) exhibit now a better balance and the difference in the noise is only 0.3 to 0.8dB, considering our preamps and RX channels are perfectly matched in gain this is a tremendous advantage due the fact in the old system the Vertical channel was always up to 5dB more noisy, in adaptive polarization is a must to have both channels balance in gain as much you can and now we are in a very good position.

6- Initial test showing almost same performance compare with other similar stations but we need to run the system several days to feel the improvement, never the less until now we didn't find really weak signals, the performance can be compare and estimated only with very low QRP stations and this will come during the next days but I'm very confident our system is better now.

7- On the TX side independent of the SWR improvement we don't see any difference compare with the old system, probably mainly because the feed design is almost the same and in the TX part the new LFA antennas are almost on the same position but TX was never a problem, we TX perfect circular and this is the way we want.

8- But we gain in performance on the 2m and now the 70cm system is a little affected, initial test show us 1dB less sun noise on 70cm, the LFA feed looks much more invasive than the old one and probably out total shadow over the 70cm feed now is bigger, we will try to find a compromise increasing the separation of the LFA yagis, I will inform you the progress on that part later.

Well, definitive our feed is much better now, if this will be translated in more QSO we will see but at least we don't regret every cent we spend on the new feed, more about the new performance will come in the next months when the European winter will back QRP stations on activity, we will see. but definitive the LFA antennas are much more quiet and noise immune than traditional design.

Well Justin, thank you very much for your support and great product,

We are in touch

73 de Alex, HB9DRI

 

 

 
 
 
 

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