Looks like the aerial of the passing car is also causing interference with that 'flat-edged black shadow'...
Friends, I want to bump this brilliant observation from Mr Finch. When he posted it, I didn't realize its significance!
Look at what happens to the car aerial when it meets the Lovelady 'shadow':
Why, the aerial
disappears, but
only in the Lovelady 'shadow' area! Once it's past that 'shadow', it pops back into visibility!:
What a peculiar aerial, you must be thinking!
But!
What if it's not the aerial that's causing interference with the 'shadow' but the 'shadow' that's causing interference with the aerial?