Explanation: An "Antenna not connected" alarm on an Inmarsat-C terminal typically indicates a break or high resistance in the coaxial cable connecting the terminal to the antenna unit. Many satellite terminals provide DC power and control signals up the coax to the LNA/antenna, and also perform a continuity check. Shorting one end of the coax and measuring resistance from the other end is a direct way to test the cable's integrity. A good cable, when shorted, should show very low resistance (ideally less than one ohm). High resistance indicates a break, damage, or poor connection within the cable, preventing proper signal transmission and potentially DC power delivery, thus triggering the alarm. Changing satellites (B) will not fix a physical cable connection issue. Replacing the antenna unit (C) is premature without first verifying the cable, which is a common point of failure. The AZ-EL board (D) controls antenna pointing, which is unrelated to a fundamental "Antenna not connected" alarm.