Topband: how to check a BOG

[Bob K6UJ]

How do you plot the directivity of your BOG ?
I am toying with the idea of either transmitting from my car HF rig 
(milliwatt sig)
and plotting the pattern from diff directions or is it possible to 
transmit with the BOG with
a real low milliwatt sig ? I was thinking then I could drive around with 
my HF rig in the car
in about a half mile radius and see if I could plot the pattern. This 
might not be doable,
but thought I would throw it out there.
How do you test your BOG ?

Bob
K6UJ