Hi Charles..
There's lots of info on the Magnetic Slot on L B
Cebik's page...W4RNL http://www.cebik.com/
L B has done extensive comparisons amongst all that group of antennae..Delta
Loop, Half Square, etc.
I've not "done one" yet, but I intend to try one on 80m.
Happy huntin'
John EI7BA http://www.iol.ie/~bravo/