about negative polar plots not defined in python not even matlab

[Robin Becker]

.........
> polar(power,theta)
> title.....?
> how can i show the step on the polar plot  plot(-40, -30,-20,-10,0)
> 

I think you need to consider why you want to plot negative values. The 
decibel scales are actually logarithmic ie all power is actually 
positive. Zero power corresponds to -infinity.

In practice, I think your radiation pattern plot might correspond to 
gain (or attenuation). Just relabel your plot and change the values to 
positive. If you do that and the plots look familiar then you have an 
answer.
-- 
Robin Becker