No way I would have bad contacts or moisture ingest. I did similar measurements on single antennas that were coax fed and these gave identical results. The effects I disclosed are mainly antenna related, not open wire feed. This probably only works in California :-) Solder connections at dipoles outside non protected. No offense but most US made antennas are mechanical crap, not able to resist UV and rain. I had some, most baluns or dipoles dropped apart after a few years outside. He tries his best but his designs are to mine opinion 'over optimised' and very lossy using 12,5 ohms apprach, and far too narrow banded. His designs are broadbanded and hell he knows why.ĭK7ZB is currently very popular in European magazines with loads of publications. I did not expect to get so many comments, but it is true I highlighted a yagi phenomenon not a lot of people are aware of.ĭL6WU is the father of yagi optimisation 'old style'. But only with QSO partners in dry area's :-)īEWARE of computer (over)-optimised yagi'sĬomments appreciated: to a comment by : ON7WP on If this would have been a DL6WU yagi array, peak gain might have been a fraction of a dB less, but ON5OF would have been able to keep bouncing in this adverse weather. No need to say the impact of this resonance drop on the gain characteristic. Look what happens.Īfter a night of rain I registered this plot in the next morning, rain still pouring down.

Then rain starts dropping, just a little, enough to make the antenna slightly wet. Let me start with a picture of the return loss of this antenna when it was still dry: He has a very nice home brew 8 yagi array with open feeders to minimize losses. I will write a more in depth article revealing the details and pulling some over exaggerated designs off their statue, but I would like to start with an illustration of what I witnessed while tweaking my friend ON5OF's EME array in France last January. So why bother to optimize to get a tiny 0,2 dB more if the antenna gets useless in rainy weather (the time we most spend inside our shacks). Old DL6WU designs that are far more broad-banded and thus more tolerant to construction failures do not suffer at all of this rain degradation. With optimized yagi's like the DK7ZB design this is a very narrow cliff. A Yagi is kind of a low pass filter with very steep performance degradation above the optimum frequency. While all yagi's performed fine in good weather conditions, they all dropped significantly in center frequency when it started raining. Recently I had the time to setup a measurement in my garden to determine the gain characteristics of some common yagis on 70 and 23 cm using Anritsu network analyzers. Or the Real Truth About Optimized Yagi Antennas. A Scary Tale About the Rain Impact on Yagi Antennas

Dl6wu yagi design program