Reflectenna: a quasi passive on-off keyed microwave telemetry system for remote sensor applications

A method to transmit one-directional wireless data with low power consumption has been investigated. This system, called the ´reflectenna´, works on the principle of transmitting information by modulating an incident continuous wave carrier signal prior to re-transmission and consists of two orthogonally linear polarised, micromachined microstrip patch antennas and a single-pole-single-throw switch that modulates the carrier signal. This quasi-passive method to transmit data has been tested with a transceiver system that transmits a 10 GHz carrier signal and demodulates the received signal reflected back from the reflectenna. The carrier signal was modulated with a 2 kHz square wave and a link with a range up to 25 m was achieved.