Microwave Moisture Measuring Sensor NEED HELP!

Discussion in 'The Projects Forum' started by kayjabbar, Sep 8, 2016.

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  1. kayjabbar

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    Sep 8, 2016
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    Hello,

    I used to be a senior member to this forum years back ,but unfortunately I forgot the password and alternative email address is also not accessible (forgotten password of that too):p, its great to see this forum in such an attractive new theme.

    Anyways I am currently working on a university project which is about measuring the amount of moisture and density on Yarn/ Fibre Strands after starch or other chemicals applied to it.

    I came across a similar principle of measuring moisture and density through Microwave Moisture Sensing Mechanism.
    The idea is that a semiconductor oscillator generates microwave energy which is absorbed by water molecules present on any substrate( as I have yarns) and on the other side of the yarn sheet second microwave sensor (detector/receiver) is present which detects the amount of energy absorbed by water and the remaining is displayed which can be further calibrated to moisture and density levels.

    The attached file is exactly what I want to design, yarns will run between these two sensors.



    My question is what can be those two microwave oscillating semiconductor and the microwave sensor/detector on the other side.

    Please anyone help me what components can do the required job.

    Some further information for understanding is provided in this link
    http://www.google.com/patents/US4674325
    This patent gives the basic concept but I would like to do this with latest technology here they are using motors for resonators.
    Find the attachments too.

    I want to know what will be the circuit diagram and what components can do such job of generating microwaves and receiving to show differences when the wave strikes the object.



    Please Help Me for creating this circuit in an easy way.


    Thank you everyone,
    I am waiting for your replies.
     
  2. jpanhalt

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    Jan 18, 2008
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    The patent gives you the basic design. This article gives you the approximate frequency:
    http://www1.lsbu.ac.uk/water/microwave_water.html (microwave 2.45 GHz)

    There must be a lot of information on transmitters and receivers at that frequency.

    John
     
  3. jpanhalt

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    Jan 18, 2008
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    Or in the alternative, just pull your yarn though a microwave oven and measure its temperature increase with an IR (no contact) thermometer.

    You will need to standardize the conditions and get or modify a microwave oven for continuous operation.

    John
     
  4. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    There's nothing to do with microwave oven or heating the yarns...its just a mechanism of microwaves (electromagnetic waves) which measures moisture and density of an object.
    microwave oven is not the thing.
     
  5. kayjabbar

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    Sep 8, 2016
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    I don't want to cook anything please read the thread thoroughly its nothing to do with MICROWAVE OVEN or HEATING.

    The yarns coming from the starch box are already at 90 degree temperature.
    I don't want any microwave oven..

    I want to design a contactless moisture meter
     
  6. jpanhalt

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    Jan 18, 2008
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    Unfortunately, you don't seem to understand that the patent describes absorption of microwave radiation by the yarn. That absorption is proportional to the moisture content. What do you think happens to that absorbed energy?

    Sorry to confuse you with an alternative. Just copy the patent and your should be fine.

    Good luck on your project.

    John
     
  7. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    I simply want a microwave signal generator and microwave signal reciever schematics
     
  8. jpanhalt

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    What frequency of microwave do you want?

    As you know, 2.45 GHz is frequently used for microwave ovens, but apparently that is not what you want.

    Have you tried Google?

    John
     
  9. kayjabbar

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    Sep 8, 2016
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    Yes i have tried google alot...

    I want frequencies ranging from 400mhz to 3ghz..
     
  10. jpanhalt

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    Why? Does water absorb over that entire region? Quantitative determinations using broad-band excitation and detection are not very accurate. Have you looked at the absorption spectrum for water? In other words, did you understand the link I gave in Post #2? If not, what parts were not clear?

    Was your previous "lost" account user name Ritesh?

    John
     
  11. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    This upoaded file is exactly what i am trying to design myself...i am checking for the exact frequency at which it can provide us moisture I'll get back with it.

    No my earlier id was aq_rules.
     
  12. kayjabbar

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    Sep 8, 2016
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  13. ian field

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    Oct 27, 2012
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    One of the TV satellite frequencies is commonly known as the; "rain absorption band" - the military didn't want that band for obvious reasons.

    You could also research why 2.45GHz was chosen for microwave ovens - it agitates the water molecules in food (and therefore absorbs energy) - but is it the most effective frequency to do that?
     
  14. kayjabbar

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    Sep 8, 2016
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    The article i uploaded now says that the frequency used are low upto 1ghz for moisture measurement....
    We dont need to heat the water molecules so keeping the microwave oven aside and their frequencies we need to focus on moisture present in fibres or any nonconductive material.
     
  15. jpanhalt

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    As I asked before, but you didn't answer, what happens to the energy absorbed by the molecules? Absorption of any of these microwave frequencies will "heat" the water. The absorption bands are due to excitation of rotational and translations movements of the water molecules.

    Have you read post #2? Do you understand it?

    John
     
  16. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    Nothing happens to the energy absorbed by the molecules.

    I posted a link at post#12

    Read the last line carefully. This was the reason i shared this link to you.
    "The microwaves do not heat or change in any way the material, due to the extreme low energy emitted ( it would need approximatelly one thousand emitters to cause any measurable effect)."


    The energy is just absorbed as very low energy is emitted as stated above and rest of it strike the sensor which detects the difference and gives some deflection to a scale which is then calibrated to moisture percentage by means of calibration curve.
     
  17. kayjabbar

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    Sep 8, 2016
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    Another file thats attached with post #14 says

    The Microwave Measurement Method

    The microwave moisture measurement method reacts with high accuracy to the water molecules in the
    product. This selectivity results on two attributes of the water molecules:
    1. Water molecules possess a strong electrical dipole field which shows a good measurable effect to an
    external electrical measuring field.
    2. Water molecules are very small and movable, much smaller than e.g. sugar-or fat-molecules.
    The introduced microwave measuring system produces an external, processor controlled electrical
    measuring field with very low electrical power and an extremely high polarity changing rate at the sample
    applicator. This change of polarity takes place with a frequency in the lower gigahertz-range i.e. more than
    1000 million times per second and a wavelength of about 10 cm which explicates the general terminus
    ‘microwave technology’.

    If now a sample is placed into this microwave field, the bipolar water molecules orientates with the
    oscillating external field and begin rotating. Bigger molecules or e.g. ions of mineral salt are not small enough
    to follow the high rotation rate of the water molecules. The rotating of the molecules with the oscillating
    external field influences the external field itself in a measurable way.
    The practical realization of the microwave method is based upon the resonator method. The low power
    measuring field (max. 10 mW) resides either inside a metallic cave or upside a plane plate. Due to an
    extremely exact three-dimensional design of the measuring field there is no ambient emission of electrical
    energy and no warming up of the product.

    Two microwave parameters are measured accurate and fast from the interaction between electrical field and
    water molecules: energy loss and frequency change of the electrical measuring field. The instrument now
    determines the result out from the two parameters by means of a patented method. The system registers the
    complete amount of moisture contained in the sample volume: surface-moisture and capillary bound moisture.



    I hopes now this is clear to you that nothings going to heat up by absorption of energy.
     
  18. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    The microwave ovens operate at 2.5 ghz and wavelength of 12.2 cm.

    Here we need frequency of 1ghz and wavelength 10cm.
    I need help in microwave emitter and detector schematic.
     
  19. jpanhalt

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    I am sorry, metaphysics is beyond my level of understanding. Something does happen to the energy that is absorbed.

    John
     
  20. jpanhalt

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    How can a lower frequency have a shorter wavelength? Metaphysics again?

    John
     
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