The beauty of the pennant and similar designs is that ground conditions does not have much effect on the achievable null depth
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/connelly.html
Experiences from the initial testing in the real world of the Pennant design
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/transformer3.html
While the Pennant is easier to build, the Flag is symmetrical and therefor adaptable to a rotatable configuration.
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/flag_w7iuv.html
Test for your Pennant. If it does not pass, it has a problem that can cost you weak signal reception
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/test.html
Several times the flag heard stations which were completely inaudible on the other antennas
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/transformer.html
The Flag antenna is particularly good for DX-ing in specific direction. The antenna is simple to construct, is relatively small, and has no direct connection to ground
http://www.hard-core-dx.com/nordicdx/antenna/loop/flag/flag2.html