[PCR-1000] Antenna suggestions wanted

[Phuzz]

Hello all!

   I have finally got around to setting up a not so long longwire
antenna in the backyard of
My house and have got alot better reception (especially in the lower
frequencies) then sticking
the arial the PCR1000 comes with out the bedroom window. The new setup
is fairly simple, a length
of copper magnet wire about 18 feet long running parallel to the top of
the side fence. It is fed 
Into the radio with co-ax attached at the end of the antenna closest to
the house. The radio is also
grounded using thick copper wire and a 3' steel pole rammed into the
ground just outside the house.
With the new antenna however, I am getting a lot of noice below 25 Mhz
and its something I would
Like to try and deal it. So I'm coming to this list for suggestions.
First off, should I go for a better
ground? Should the grouding rod be copper and how deep do I really need
to go. I live in a rented
townhouse so any and all antenna creations must be very subtle and
without any major manipulation of 
The yard/house/neighbourhood :) Second, what can I do to improve the
noise resistance of the feed line
Into the house? The coax feed is only about 6 feet from antenna to
radio, but Im wondering if its picking
up a lot of the electrical noise from the house. Would it be better to
move the connection to the antenna wire
To the far end of the line, away from the house and run the coax back
from there? Finally, as I stated, I am
Currently using a straight piece of wire attached to ceramic insulators
at each end. My yard however has a fence on three sides, like a 'U'
shape in behind the house. I am currently only running wire down the one
side. Would it be advantagous to make an L or U shaped antenna that
travels around all 3 sections of the fence? The antenna runs about 5
feet of the ground.
Any ideas/suggestions/comments would be greatly appreciated. Thanks in
advance' 

PS: I am more interested in antenna ideas for below 50 Mhz....