1ghz Microwave oscillator sensor (Emitter) and a Microwave Detector sensor.

Discussion in 'The Projects Forum' started by kayjabbar, Sep 10, 2016.

  1. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    Please can any one help me in designing a 1GHZ microwave/EM wave emitter circuit diagram, and a microwave detector sensor?
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
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    RMS voltage? Current?
    How far apart are the source and sensor?
     
  3. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    110mm apart from each other.

    I don't know the rms voltage current required.

    All i need is an emitter source generating 1ghz frequency or upto 10cm wavelength,
    When it hits the detector sensor , it should display the frequency coming from the source.

    So if i place any sheet of material between the 110mm gap the sensor should display the remaining frequency (as some of the frequency is absorbed by water molecules or some dielectric present in the sheet).

    I hope you get it
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Placing anything between a sensor and your microwave transmitter merely reduces the strength of the detected signal.
    If you transmit at 1 Ghz you will always detect a 1 Ghz signal, unless the strength of the signal falls below detection limits, and even then it will still just be a very low strength 1 Ghz signal.

    The frequency will not change unless the transmitter changes its output frequency.
     
  5. Alec_t

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    Sep 17, 2013
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    up to 10cm = >3GHz !
     
  6. Alec_t

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    This may help. So may this.
    Be aware that at this frequency you won't get away with building the circuit on a breadboard or perfboard. Circuit layout will be critical.
     
  7. kayjabbar

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    Sep 8, 2016
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    See the file i uploaded...it explains with a graph what i want to do.
     
  8. kayjabbar

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    Sep 8, 2016
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    Can you explain me this schematic of 10mhz to 1ghz as im already gone through it and confused with it...where is the microwave signal output and what component will be used to direct waves towards the material..i mean it will be an antenna or photodiode or a photo transistor..in short what emits waves and how?
     
  9. Alec_t

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    Sep 17, 2013
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    It's a VCO. The frequency is controlled by the voltage applied to the varactor D1. Output is coupled capacitively to a 50 Ohm transmission line from pin 5, which has a tank circuit L2/C6 as a load.
    The 110mm distance between emitter and receiver is about 1/3 of a wavelength at 1GHz. It is my understanding that conventional antennae are unlikely to be directional in such near-field situations.
     
  10. kayjabbar

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    Sep 8, 2016
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    So what transmission source you would recommend for this condition?
     
  11. kayjabbar

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    Sep 8, 2016
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    And what will be the detector schematic can you post any which could display the remaining frequency after it st4ikes an object?
     
  12. Alec_t

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    Sep 17, 2013
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    Sorry, I'm not an expert at near-field transmission. Someone else may be able to help on that.
    Something based on the amplifier in the second link in post #6 perhaps, followed by a rectifier and smoothing circuit to get a voltage indicative of received signal strength.
     
  13. DickCappels

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    Aug 21, 2008
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    Reading the pdf it appears that the amount of water in a sample placed in a resonator affects the oscillation frequency and by measuring the shift in frequency when a reference sample (can be an empty resonator) is replaced by the sample to be tested the amount, and measuring the power absorbed by the sample, the amount of water in the sample can be estimated.

    The oscillation needs to be around 2GHz and there needs to be a way to messure the oscillation frequency and the power absorbed by the sample.

    It sounds like a very sophisticated instrument.
     
  14. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    Sir can you please help me in the circuit design for the source and sensor?
     
  15. Alec_t

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    Reference circuit designs are given for both the source and sensor in the links I posted. Did you read them?
     
  16. BR-549

    Well-Known Member

    Sep 22, 2013
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    kayjabbar, you are trying to build a "metal detector" for water. And it should work. What is the cross sectional area of the media exiting the process? In other words, what is the target size and shape?

    You need an oscillator that slowly sweeps from a little lower than 1 GHz to a little above 3 GHz. Once you find the resonance of your process, you can limit or eliminate that sweep range. It shouldn't need much power.

    I don't know your setup, but maybe a loop around the exiting media, or a dipole in parallel with it.

    The idea is sound, but I am not qualified to build it. There are people on this site that could.

    You could use of the shelf parts, or have a contractor build it for you. If you need to build it yourself for school or something, you are in for some headaches. You can not use bread boards. High frequency rf is fuzzy and hard to control, at least for me.

    And if the solution is needed quickly, you will need some money and professional help.

    There are many companies that do this. Search for "microwave solutions".
     
  17. dannyf

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    Sep 13, 2015
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    try to design a 1Mhz wave emitter circuit and then we can go from there.
     
  18. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    Not exactly a metal detector, its a moisture sensor, between this 110mm space of source and sensor cotton or polyester yarns/strands are passing by at a certain speed, we can say it is a web of fibres passing by the system. The degree of a absorption is a measure of absolute moisture content.
    The following file attached with this post will clear everything about my project it is exactly the same thing we are doing here.

    Please see the attached pdf file.
     
  19. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    I can fabricate PCB myself so it might not be such problematic for me to play with these frequencies, but i need help from someone who can post a schematic for the source and sensor and what type of antenna or rf radiator will be used for this near field emitting and sensing equipment.
    Please guys i need your help and support.

    Kadir Jabbar.
     
  20. kayjabbar

    Thread Starter Member

    Sep 8, 2016
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    Danny, 1 Mhz or 1 Ghz can you post a schematic for the emitter and again what type of near field radiator will be used and where on that particular schematic.
    For example i found this one much related http://www.electroschematics.com/756/10-to-1000-mhz-oscillator/.

    But the component on the right hand side labelled 50 ohm.
    Its confusing me whats that and what will be the component values for my requirements here in this circuit can anyone redraw it accordingly please.
     
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