Transponder-based microwave telemetry apparatus

A transponder-based microwave telemetry apparatus for an internal combustion engine comprising:

• a transponder disposed inside the engine for measuring a sensed condition of a piston in the engine and providing a modulated microwave signal that contains information on the sensed condition;
• and
• a transceiver disposed outside the engine to fill a crankcase of the engine with microwave energy and to separate modulated and continuous-wave signal components of the signal and extract information from the modulated component.

A transponder-based microwave telemetry apparatus for an internal combustion engine comprising:

• a transponder disposed inside the engine for measuring a sensed condition of a piston in the engine and providing a modulated microwave signal that contains information on the sensed condition, said transponder comprising a switch, an information gathering circuit, an antenna, and a power source, said switch turning said antenna ON and OFF at a frequency determined by said information gathering circuit to amplitude modulate incoming microwave energy;
• and
• a transceiver disposed outside the engine to fill a crankcase of the engine with the microwave energy and to separate modulated and continuous-wave signal components of the signal and extract information from the modulated component.