I saw
this post and decided to give it a go.
I moved out the code to draw the radar radius during an interception to a new function:
void RADAR_DrawCoverage(const menuNode_t* node, const radar_t* radar, vec2_t pos);
I then added a call to the switch for the menu message in the map drawing routine, so that the coverage is drawn when creating a new base.
Here's a zip archive with the changed files and a diff:
http:///darkwax.co.uk/kable/ufoai/radar_coverage.zip
P.s. should radar coverage really get so big when you have 3 stations? I think it might be better if coverage
area is increased by a set amount each time a new station is added, otherwise there is no motive to build radar at other bases... you can get much better coverage just building many stations at one.