There has been research with the Underwriter's Laboratory and they found that electromagnetic fields don't really impact us that much, if at all. And the nervous system sends impulses by electrical impluse, but in general, it's not the same as an antennae. Also, the Earth's magentic field doesn't change in presence or absence of sunlight, and it doesn't really send us signals. It's just on all the time, with minor variations from gelogical origins.