RX350 Satellite radio loses signal

[Boboli]

My 2013 Lexus RX350 XM satellite radio loses signal at times.  It displays "no signal".  Other cars with XM satellite radio driven over the same roads at the same time do not lose the signal.  Satellite radio is digital, therefore when signal level drops below a certain threshold it simply cuts off, unlike conventional analog radio signals (AM and FM) that will get weaker and static-filled), leaving the listener with no sound at all.  I suspect there is a problem in the satellite radio itself because the dealer rep told me the service department replaced the satellite antenna (but, he admitted today they did NOT replace the cable from the satellite antenna to the satellite radio).  

A friend of mine also has a 2013 RX350 with satellite radio so I will drive her Lexus over the same roads even though, as I said above, other vehicles with satellite radios do not cut off the signal when driven over these same roads.  

Has anyone else experienced this?  I know if you get behind an obstruction where the satellite signal can't get to your antenna that your receiver will lose signal.  But since other vehicles don't have the problem I am thinking I have a weak receiver.

Any help appreciated.  Service Bulletins?  Dealer Notices?  Anyone know of anything?

Thanks, Bob