I appreciate your responses - doing further research I came up with this:
Center airspace is divided into sectors in the same manner
as terminal airspace; additionally, most Center airspace is
divided by altitudes into high and low sectors. Each sector
has a dedicated team of controllers and a selection of radio
frequencies, because ---- each Center has a network of remote transmitter/receiver sites. ----All Center frequencies can be found
in the back of the A/FD in the format shown in Figure 9-13;
they are also found on en route charts.
Each ARTCC?s area of responsibility covers several states;
when flying from the vicinity of one remote communication
site toward another, expect to hear the same controller on
different frequencies.
Source:
http://www.faa.gov/library/manuals/a...apter%2009.pdf
The requirement for higher power may not be necessary.