I am fairly aware of the general thermistor/ diode/ thermocouple methods of sensing microwave power. Currently my requirements are simpler: A device that senses only microwave power incident on it - and not any other form of radiation.
For this I used a Pt-100 RTD and coated the sensing tip of it with SiC (a well known microwave absorber). This tip was then shielded by thermocoal (inserted into a thermocoal block), and the block was then moved through the edges of a microwave oven to capture the microwave flux leakage. On conducting this experiment, there were noticeable changes in resistance.
However, there were fluctuations in resistance (albeit to a smaller scale) even when the microwave oven was switched off, presumably due to direct heating of the RTD sensor.
Are there any glaring erros in the design? What other alternative can I use?