[Antennas] Wilson 5L15m Yagi Pattern Concerns

Tue Sep 7 17:02:22 EDT 2010

Hi Larry,
Did you match the diameters and lengths
of each section to the Wilson specs?
Again, it's not the overall length, but
the length and diameter of each section.
If not, then the taper/etc. will be off
and well, all bets MAY be off as to if
the individual elements are correct.
YES, as to the spacing will also impact
this too. However, changes in the above
should not skew the main lobe.
What/how are you feeding the yagi? Wilson
used a gamma match on many of their yagis of
that time frame ... problems with that part
of the picture may be more likely to cause
that skewing you are mentioning <after of
course checking that your rotor is accurate
as we've all been bit by that one before>.
The high SWR could be the wrong taper in
the elements, the skewed pattern sounds like
the feedline is doing some radiating too,
thus the better reports off the side/back,
or some combination of several factors.
As mentioned in another reply, some designs
will reverse their patterns if you wander off
too far from the designed range, so you could
have a combination of challenges to resolve.
If there is a local close to you, you might
do some F/S and F/B checks ... say at 21,
21.1, 21.2, 21.3, 21.4, 21.45 ... and do a
rough plot of the pattern. That's one way to
confirm of the elements are the right lengths.
Hang in there, you can overcome this, we just
need a bit more of the details to try and help.
73 de Billy, AA4NU
-----Original Message-----
>>From: LARRY D GODEK <telegrapher at q.com>
>>Sent: Sep 7, 2010 2:46 PM
>>To: antennas at mailman.qth.net
>>Subject: [Antennas] (no subject)
>>>>>>Well i am a bit cornfused as the saying would go. Let me try and explain. Maybe something that i'm overlooking, not understanding or is part of the paranormal!
>>>>Years back i bought a Wilson 5 el. 15 meter beam. Spring time this year i bought some new element tubing from Hygain and replaced some of the bent up elements. Carefully measuring all the lengths and distances between said elements on the boom. More than once i did the measuring. Anyway got it up on about 25 ft on a rotator and figured now i'd work the world on 15 which is one of my more favorite bands anyway. 
>>>>Hmmmm. Worked some dx including E51 and ZD7 along with VP8 and multiple JA's and PY's, YV's a couple of CE's and other stuff down that way. Funny thing is that when working SA the beam usually is pointing NE. The other day 5Z4EE was on CW and according to information i have the antenna should ahve been pointing about 48 degrees. I heard him the best with it pointed about 146 degrees and if i turned it right on him i couldn't hear him at all. Doubt it was propagation as a couple other hams in the area worked him just fine but nadda for me. Good SWR with no power reflected as shown on the Bird. The beam is set for the low end of 15 meaning above 21.150 the SWR starts climbing quickly. just seems that i hear stations better off the side on the antenna and back of it than i do off the front like i should. 
>>>>I've checked the beam from the ground and there is nothing loose that i can see. Elements are in line. However, if you go and look at the HyGain 155 beam it is essentially the same antenna but the element spacing is different. Now i don't know which design to believe. It's a bear for me to get up there and take that thing down but when it gets quite a bit cooler, read November-December in the desert i can do it.
>>>>gotta get it right as i'm getting to old to keep wrestling these 50 lb chunks of aluminum around up on the tower.
>>>>Anyone got any ideas? Sure like to see this thing working more like it's supposed to. Don't suppose it's just to close to the ground do ya? It's just over 1/2 wave up.
>>>>Larry
>>W0OGH