0
$\begingroup$

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?

$\endgroup$
0
$\begingroup$

Here is a way which might work better: a simple microwave calorimeter. this consists of a small amount of water in a well-insulated nonmetallic container, into which you can insert a small temperature sensor like a thermocouple. When exposed to microwaves, the water inside the container will heat up. Knowing the mass of water in the container, the delta T, and the heat capacity of water, you can then back-calculate the number of watts of microwave power that the sample was exposed to and captured while the oven was on.

it is important to NOT expose the temperature sensor or its wires directly to microwaves because they will induce eddy currents in the wires which will make them get hot enough to melt off their insulation and start burning! therefore, do not insert the sensor until you are done with the test and have shut the microwave source off.

$\endgroup$
  • $\begingroup$ The final plan is to expand this design by replicating each unit to make, say, a 1000 by 1000 array. Using a microwave Calorimeter, in such a case would not be feasible, let alone cost effective :( $\endgroup$ – user8244 Dec 8 '17 at 11:25
  • $\begingroup$ you might also try this classic trick: assemble a cubic array of marshmallows using toothpicks that fits inside the oven. turn it on and observe the resulting melt pattern! $\endgroup$ – niels nielsen Dec 8 '17 at 18:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.