is the directv cinema wireless adapter 5 ghz compatible?

Yes, but why do you want to use this device?  Whole Home DVR is designed to work with the BB adapter hard wired to your router and the installation of same is included in the installation at no added cost.  The BB adapter provides a superior connection over the adapter.

my understanding of what i'm supposed to be doing is connecting the coax to the adapter........and then connecting the adapter to the dvr via coax.  I don't see anything that tells me to connect the adapter to my wireless router via ethernet.  What am I missing?

I was considering switching my router to the 5 ghz band......

What is a "bb adapter"?

Ditto, what are talking about regarding a "bb adapter"? I just purchased Cinema Connection Kit and there was no bb adapter.

"BB Adapter" = "Broadband Adapter" = Cinema Connection Kit Adapter

ok then - now that you have clarified what you meant i'm still confused.  You make it seem that I should be connecting the ADAPTER KIT to my HOME NETWORK ROUTER via Ethernet?

Is that what you are suggesting?  Everything that I have read is telling me that since I have WHOLE HOME DVR that my connection method is Coax ONLY.

Further, the ADAPTER KIT is wireless - I don't see any instructions pertaining to hard wiring it.

The correct Cinema Connection Kit will "bridge" the coax network to your home network.  It has a coax port that connects to the SWM coax DECA network and an ethernet port to connect to your home  network router.  It should have been installed when your WHDVR system was installed. 

i ordered the cinema connection kit after i have had DTV service for several months now.  I attempted the self install and followed the directions.  Nowhere in the directions did it mention that I should attempt to connect the cinema connection kit to my home network router via ethernet cable.

Are you saying that this is an option?

No, I think you have the wrong "Cinema Connection Kit". You have their wireless adapter. The "kit" I'm referring to is typically not available for self installation.  See the info here ....

http://forums.directv.com/message/10883754#10883754

Let's start over.  Yes, the Wireless Cinema Connection Kit is dual frequency, including 5 Ghz.  As an aside, the Whole Home DVR system is designed to be all hard wired, no wireless is involved.  See the attached schematic to see how it is wired.  Also attached is a pic of the current BB adapter.  This stuff is supposed to be professionally installed when the rest of the system is put in but for whatever reasons Directv misses a lot of folks.

All of that being said, if you wish to self install a wireless Cinema Connection Kit (model DCAW1RO-01) and you have the Whole Home system, you do in fact use the coax option and begin the install on page 11 of the instructions.  Installation is normally plug n play but there are a couple of fairly common stumbling blocks.  If you should have trouble, post back and tell us what is specifically happening and we can maybe help you out.