Military personnel are covered by the U.S. Constitution, but not in exactly the same way as civilians are. While military personnel are not excluded from the rights set forth in the Constitution and Bill of Rights, Article I, Section 8, of the Constitution grants Congress the power to make rules for the government and regulation of the land and naval forces.
As a practical matter, most civilian Constitutional rights are afforded to military personnel - although with some differences to fit the military situation. In some areas, such as right to counsel and rights (Miranda) warnings, military personnel have broader protections than those contained in the Constitution. In other areas such as search and seizure, they have reduced expectations of privacy and fewer protections.
Military appellate courts tend to interpret military law as being consistent with Constitutional protections so far as is possible.