The large loop antenna is a simple antenna, especially if you already have 4 trees in key places.  Our loop has a perimeter of about 900 feet, up about 50 feet.  It is fed in the corner with 50 feet 450 ohm ladder line, which goes into a 4:1 balun, then another 25 feet of RG-214 into the shack.  Here are some views of what EZ-NEC thinks of our antenna.  Surprisingly, the SWR sweep is fairly accurate!  The radation pattern on 80 meters predicted by eznec also somewhat matches on the air test results.  Now these are not scientific, but there does seem to be a correlation, those lobes at 45 degrees are pointing right to the UK, and we consistantly work the UK barefoot.   Check out the 40 meter and 20 meter patterns.