Ipad mini Retina like IPAD Air
The iPad mini Retina does have the same radios as the iPAD air.
Thus, it generally will be usable across the various US carriers with the different sims. Note that a carrier may refuse to activate the cell connection however if it has an IMEI number for a different carrier.
Generally ATT and Tmobile are easiest to activate with the given Sim. Of the CDMA carriers, Verizon is probably easier to work with from what I have read elsewhere.