Signal to noise

I live in a rural part of Norfolk.
My mobile provider is EE...
I can't use my mobile in my village as there's no signal. Only Vodafone users get a signal in the village. If I walk up the 'hill' out of the village I get a few bars...

The Countryside Alliance has started a campaign to ask people to map their mobile signal to identify 'not-spots'.
Of course, one way to improve the mobile signal would be to have more masts - but they are not popular in the landscape either...

To join in, there's an app called Root Metrics which you can put on your smartphone. This will do a test of the strength of your call signal and data connection.
A bit of citizen science.

Are there connections with the topography of the area and signal strength ?