Prototype Microwave Circulator (image) University of Sydney Share Print E-Mail Caption This is a prototype of the microwave circulator, next to an Australian five cent piece (19.41mm diameter). Credit Alice Mahoney/University of Sydney Usage Restrictions For this story only. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.