How to Detect and Measure Low Frequency Microwave Modulation?

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#1 21673619 09 Mar 2015 20:01

Vishnu T Vishnu T

Anonymous

Post #1
21673619 09 Mar 2015 20:01

I would like to know how to detect microwave modulation at low frequency and I would like to know measure it
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#2 21673620 10 Mar 2015 16:39

richard gabric richard gabric

Anonymous

Post #2
21673620 10 Mar 2015 16:39

You don't say what frequency, low is not much help.
PIN diodes are often used, a quick search using "microwave modulation detection using diode" yielded some results.
If you are talking the low end of the microwave spectrum, there are a number of Integrated circuits that will do the job, the LTC5564H is an example.
Cheers,
Richard
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#3 21673621 10 Mar 2015 20:21

Orin Laney Orin Laney

Anonymous

Post #3
21673621 10 Mar 2015 20:21

PIN diodes are used to create amplitude modulation (and for switching), but are useless to measure it. For that you want a detector diode, or as pointed out, any of a number of ICs that can strip LF modulation off of a microwave carrier. Analog Devices, Maxim, and Linear Tech all make these.
#4 21673622 11 Mar 2015 18:57

Vishnu T Vishnu T

Anonymous

Post #4
21673622 11 Mar 2015 18:57

I understand that we can only detect microwave using devices .

Any hand portable device that we can detect microwave modulation at low frequency ?
Anything that we can see the heat from microwave around us using software or other tool ?
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#5 21673623 11 Mar 2015 18:59

Vishnu T Vishnu T

Anonymous

Post #5
21673623 11 Mar 2015 18:59

I am looking for detection microwave at low frequency 0 to 100 Hz , and I am looking also for visualization of microwave around us ?
#6 21673624 11 Mar 2015 20:41

Orin Laney Orin Laney

Anonymous

Post #6
21673624 11 Mar 2015 20:41

It sounds like you're looking for a field strength meter. Narda Microwave, lessemf.com, and a bunch of other people offer them, and I'm sure you can find low cost options in ham radio publications. You probably want a broadband rather than tuned design. Unless your field strength is really low you could probably make adequate qualitative measurements by cobbling up a microwave version of a crystal radio - just a single turn loop with a microwave schottky diode between the ends, and an RC filter across the diode into a headphone amplifier to listen to the modulation. Of course, your ears don't go down to zero hertz, so you'll want a meter for the DC component. Google up "microwave field strength meter plans" for more elaborate schematics.
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#7 21673625 21 Mar 2015 07:37

Vishnu T Vishnu T

Anonymous

Post #7
21673625 21 Mar 2015 07:37

I got the sound signature file. It is really strange and cant figure it
#8 21673626 21 Mar 2015 09:38

Orin Laney Orin Laney

Anonymous

Post #8
21673626 21 Mar 2015 09:38

Listened to the sound file, but with zero information on what it is you are listening to I can only make one guess. This sounds like the switching harmonics of a microcontroller executing a control loop. every time a button is pressed or some other event is processed it goes into the appropriate subroutines and returns. This shows up as the momentary noise changes. The rest of the time the loop just goes round and round waiting for something to happen. Am I right or even close?
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Topic summary

The discussion addresses methods to detect and measure low frequency modulation on microwave signals, specifically in the 0 to 100 Hz range. Detection typically involves using microwave detector diodes rather than PIN diodes, which are suitable for modulation generation but not measurement. Integrated circuits from manufacturers such as Analog Devices, Maxim, and Linear Technology can demodulate low frequency modulation from microwave carriers. The LTC5564H is cited as an example IC for this purpose. For practical measurement, field strength meters from companies like Narda Microwave or low-cost broadband designs found in ham radio resources are recommended. A simple homemade detector can be constructed using a microwave Schottky diode, a single-turn loop antenna, and an RC filter feeding a headphone amplifier to qualitatively listen to modulation, though a meter is needed for DC component measurement. Visualization of microwave fields and portable detection devices were also queried, but no specific solutions were provided. Additionally, a sound file related to the modulation was discussed, with speculation that it might represent microcontroller switching harmonics rather than direct microwave modulation.
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How to Detect and Measure Low Frequency Microwave Modulation?

How to Detect and Measure Low Frequency Microwave Modulation?

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