Signal loss in S.E. Massachusetts

We have factory installed Sirius radios in a 2010 Toyota Highlander and a 2006 Mercedes E320. Until Fall 2013 we had these vehicles in Las Vegas, NV and never experienced any signal loss or dead zones. Now we live in Plymouth, MA and we are CONSTANTLY dealing with dead zones and signal loss. And the signal loss occurs in the same parts of town (and actually in many places in SE MA) with both cars. This tells me it isn't a hardware problem, but a signal strength issue.

Am I correct? Are other subscribers in SE MA having the same problems? Any suggestions?

Rural areas of marshfield, duxbury, and plymouth kill my signal because of all the overhead trees and power lines crisscrossing the streets. I can drive down a back road and the signal cuts out every 10 seconds as a power line crosses above the road.

I live right outside of Boston and the signal is great. When I head down towards the beaches during the summer, the signal sucks. I have lots of family on the south shore.

it's the same here in south florida going east to the beach i always lose the signal, and sometimes going north or south on I95 you lose the signal for miles.

I thought my antenna was going bad, but some of my coworkers that have sirius have the same issues