Complex sentence: The S band is a designation by the Institute of Electrical and Electronics Engineers (IEEE) for a part of the microwave band of the electromagnetic spectrum covering frequencies from 2 to 4 gigahertz (GHz).
Split into simpler sentences: The S band is part of the microwave band of the electromagnetic spectrum. It is defined by an IEEE standard as frequencies that range from 2 to 4 gigahertz (GHz).