A 50-ohm non-inductive resistor mounted on a heat sink✓پاسخ درست
A low-voltage power supply and a DC relay
A 50-ohm inductive reactance mounted in a shielded enclosure
توضیح
A dummy load must look to the transmitter exactly like a matched antenna, so it is a non-inductive resistor of the system impedance, normally 50 ohms, mounted on a heat sink or in oil to dissipate the power as heat. A reactive load would not present a match and would reflect power back.