[TowerTalk] OWA YAGIS and YO Version 7.07

[Stan Stockton]

Just for kicks put the numbers found on the internet for the popular OWA yagis into YO.  Following is the output from YO for the 6L20, 6L15 and 7L10 all on 48 foot booms.  

I used the diameters and lengths, plate sizes and spacing as found in the article and specified direct feed with 50 ohm coax.  

I am wondering if anyone has an idea as to why the results are so different from you would expect.  The 20M one is off by a bunch in the feedpoint impedance category.  The others are reasonably good looking antennas according to YO although the gain on 10M shows to be down from maximum by 1.4 dbi until you get up in the part of the band you would rarely use. 

The real question is whether YO is off as much as would be indicated as compared to whatever the gold standard of modeling would be, am I doing something wrong or what??

20M:

14.000 9.91dbi 20.24 F/B 34.1-j8.3 1.54 SWR
14.175 10.11 dbi 24.45 F/B 31.2+j1.6 1.60 SWR
14.350 10.29 dbi 23.29 F/B 28.9+j12.4 1.88 SWR

15M:

21.000 10.98 dbi 23.71 F/B  43.3+j1.4 1.16 SWR
21.225 11.28 dbi 25.97 F/B 44.7+j8.3 1.23 SWR
21.450 11.51 dbi 24.98 F/B 49.7+j8.4 1.18 SWR

10M:

28.000 11.37 dbi 23.94 F/B 42-j1.2 1.19 SWR
28.500 11.37 dbi 23.94 F/B 42-j1.2 1.19 SWR
29.000 12.46 dbi 27.39 F/B 53+j17.3 1.4 SWR

Thanks...Stan, K5GO