Last night I figured out the math to plot nice cardioid patterns, and this morning I finally got the rotation right, so now the PHG plotting shows the directivity parameter, too. It's been requested by quite a few users since I got the circles going.
The first image shows a PHG plot with an omni pattern (no directivity), and the second image shows a PHG plot with a directional antenna pointing at 135° (southeast). Please bear in mind that these plots describe very rough approximations and best guesses about the station's service range.
You can generate a PHGR comment extension for your digipeater or igate using the PHG calculator. Please monitor your station's receiver performance and adjust the PHG settings to match the observed range.