Options I can think of:
1) raise it higher - as it is just at height or slightly above height
of brush and smaller trees. I plan to do this for permanent install,
but wanted to experiment with it at this lower height. Some articles
say 40' but will perform even at 20 or even 10'. Shouldn't I have
better results with this at 25-30 feet?
As you probably know already, height is everything. Sure it works at
a lower height, but it works better higher. You'll have less
interactions with the ground and other metal objects the farther away
from them you are, and this will affect your SWR readings.
2) Change to 450-ohm ladder line. I am thinking this will help get
better SWR into the shack, but was expecting the antenna on its own to
perform better. Or is the feedline part of the magic of making this
The nice thing about a long loop is it's an efficient radiator for any
frequency that is equal to or below it's total length. The SWR could
be horrible but if you can get power into the antenna, it will
radiate. By using a good tuner, you can show a clean 50 ohm load to
your txvr. If you are running balanced line to the antenna, even if
you have an swr of 1:10, you aren't losing the power. That is unless
you are running unbalanced line over a segment with high SWR, if so
you increase the cable loss significantly. If I had any choice at
all, I'd run ladder line for any multi-band wire antenna.
3) Assume this is how all loops work and people don't care about the
antenna SWR and fix it with feedline and/or tuners? I'm not seeing
the seeing the upside of having a loop at its current performance. I
think I may be doing something wrong.
I can't speak to others, but I don't care all that much, I can account
for the antenna with a tuner, and I have confirmed in comparisons to
my yagis, that my modelling in nec seems quite accurate with respect
to gain. Anecdotally, I heard a UAE station on the air, and tried for
over an hour to work him with my 40m two element yagi, to no avail. I
figured I'd give the loop a shot as he might be in one of my high gain
lobes (my loop is ~1000 ft, so it's 8 waves on 40m) and I got him
immediately. So loop wins for that contact vs. two element 40m yagi
at 90 feet.
4) I miscalculated something? I am hoping you can give me some good
advice of things to try.
I may have missed it in your description, but you should at least put
a 1:1 current balun either at the antenna feedpoint if you insist on
feeding it with coax or at the end point of your ladder line. (Some
tuners will have a balun in them, so if you run the ladder line all
the way back to the tuner's balanced line output you may not need
It looks like you aren't too far down the road from here (by olympic
peninsula distance standards).