He entered the field of radio astronomy, working at the Cavendish Laboratory, Cambridge, after war service in military radar research. Hewish made both practical and theoretical advances in the observation and exploitation of the apparent scintillations of radio sources due to their radiation impinging upon plasma.
This led him to propose, and secure funding for, the construction of a large array radio telescope at Cambridge in order to conduct a high resolution radio sky survey. In the course of this project, one of his graduate students, Jocelyn Bell, first noticed the radio source which was ultimately recognised as the first pulsar.
The paper announcing the discovery had five authors, Hewish's name being listed first, Bell's second. The Nobel award to Hewish without the inclusion of Bell as a co-recipient was controversial, and was roundly condemned by Hewish's fellow astronomer Fred Hoyle.