Design and implementation of a microwave cavity resonator for modulated backscattered wave

Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Electrical and Electronics Engineering, Turkey

Approval Date: 2015


Supervisor: ŞİMŞEK DEMİR


In this study, the device called “Theremin’s Bug” which is a passive microwave cavity resonator is analyzed in detail and a similar device is designed, simulated and implemented. The device being the predecessor of modulated backscatter wave communication devices, RFID devices and microwave wireless sensors is invented by Russian inventor Leon Theremin in 1940s, and used as a covert spy device. The structure is totally passive and contains no electronic component and no battery. It uses the modulation of backscattering electromagnetic waves technique and resembles a passive microphone since it reflects the incoming wave by modulating with the ambient sound. Since the device was a secret, there is no exact information about the technical details and principle of operation of the device. All the information about the device is consisted of stories and tales. And there are many technical inconsistencies about the device and working principle. In this work, the device is studied analytically and a practical prototype is implemented.