SJ 13 (Shi Jian 13), also known as, is a Chinese experimental geostationary communications satellite, which is to test electric propulsion on a DFH-4S bus. It is to be operated as ZX 16 (ChinaSat 16) after the experimental phase.

Besides testing the electric propulsion, the satellite is also reported to carry China's first high-throughput satellite payload (HTS), with a capacity of 20gb per second. The satellite is aiming to provide Ka-band satellite broadband and multimedia services. China Satcom is responsible for the construction and operation of the satellite. The satellite will be located at 110.5° East and the design lifetime is 15 years. The satellite is able to provide 26 user beams covering China and offshore areas and will serve for distance learning, medicine, internet access, airborne and maritime communications, and emergency communications.

Additionally it is also to conduct space-to-ground laser communications experiments.