Microwaves - general questions

I am studying Microwaves and have some questions I hope someone here can answer.

I understand that microwave ovens use a particular frequency of microwave to heat the food - actually the water contained in foods. I am curious as to the use of metal in microwave ovens. Is it true that the microwaves will bounce off the metal surfaces inside ?

I know one should not put metal object in microwaves. However, if microwaves were directed at an object, with a single layer of tin or aluminum foil in between the microwave source and the object - would that totally block the microwaves from the object ? If so, does the foil need to be tied to any sort of ground - or is it just the fact that it is metal ?

In the above case, would the foil become warmer due to being struck by microwaves ?

Is it true that some types of gases will also block (or greatly absorb) microwaves ?

Are microwaves strictly line of sight - that is in their use in communications ?

What would be a good source of LOW POWER microwaves for studying such issues ? I am not about to play around with the high voltage parts of a microwave !

Does anyone know of low cost modules (IE: Ebay) readily available that can detect the presence of microwaves ?

Is it true that the microwaves will bounce off the metal surfaces inside ?

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Yes, the idea in an oven is the waves are reflected off the sides and back into the food.

I know one should not put metal object in microwaves. However, if microwaves were directed at an object, with a single layer of tin or aluminum foil in between the microwave source and the object - would that totally block the microwaves from the object ? If so, does the foil need to be tied to any sort of ground - or is it just the fact that it is metal ?

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Almost 100% of the waves will be reflected from a large surface but beware that small conductive items may resonate at the microwave wavelength and absorb energy. This is why it is recommended that metal objects are not used. Grounding makes no difference.

In the above case, would the foil become warmer due to being struck by microwaves ?

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Not appreciably unless resonant as mentioned earlier.

Is it true that some types of gases will also block (or greatly absorb) microwaves ?

Click to expand...

No idea but quite likely at some microwave frequencies higher than used domestically.

Are microwaves strictly line of sight - that is in their use in communications ?

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Yes but to some degree they are subject to 'bending' or refraction due to atmospheric conditions.

What would be a good source of LOW POWER microwaves for studying such issues ? I am not about to play around with the high voltage parts of a microwave !

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Look out for Gunn effect devices. They are widely used commercially for speed and motion detection. They only produce a few mW and typically run from about 8V.

Brian.

dxpwny said:

What would be a good source of LOW POWER microwaves for studying such issues ? I am not about to play around with the high voltage parts of a microwave !

Does anyone know of low cost modules (IE: Ebay) readily available that can detect the presence of microwaves ?

Click to expand...

I would recomend an SDR radio. A HackRF(or similar) would make a really useful too to see whats going on in the EM spectrum.