How to delete a coil signal.

Thread Starter

Christos7

Joined Jan 4, 2021
3
Hello!I have a construction with two coils,of a transmitter and a receiver one next to the other and at a distance of 1 meter between them. A 1volt signal is induced in the receiver coil by the transmitter.
My problem is that I have to completely turn off the 1volt signal on the receiver because I have to make a big boost to get the signal from a metal target that I have in front of the receiver coil. Any idea?
Thank you for your time and best regards!!!

Christos
 

jpanhalt

Joined Jan 18, 2008
10,913
Welcome to AAC.

I can picture the two coils, but this sentence is unclear to me:

" My problem is that I have to completely turn off the 1volt signal on the receiver because I have to make a big boost to get the signal from a metal target that I have in front of the receiver coil. Any idea?"

Are you trying to block the signal or boost the signal? At what frequency is your transmitter working?
 

Thread Starter

Christos7

Joined Jan 4, 2021
3
" My problem is that I have to completely turn off the 1volt signal on the receiver because I have to make a big boost to get the signal from a metal target that I have in front of the receiver coil. Any idea?"
I have a 10khz transmitter coil and a receiver coil.
The signal leaves the transmitter goes to a metal surface opposite it is reflected and received by the receiver coil.
Also the receiver coil receives the signal directly from the transmitter, i.e. the receiver coil receives two signals one from the transmitter and one from the metal reflection in front of them.
So,i have two signals to the receiver coil and i must to block the one from transmmiter and to boost the other from the reflection.

Thank's for your reply!
 

jpanhalt

Joined Jan 18, 2008
10,913
That wavelength is about 3x10^4 m (30 km). They are hard to block and any antenna will be a small fraction of a wavelength.

Such extremely low frequencies have even been used to communicate with submarines. WWVB is at 60 kHz and travels quite far.

Why "must" you try to block that radio wave?
 

Papabravo

Joined Feb 24, 2006
14,831
What you want to do is very likely impossible. There is no way to distinguish between the two as the distance appears to be a fraction of a wavelength. Contrast this to a radar signal in which the wavelength is a teeny-tiny fraction of the round trip distance.
 

Danko

Joined Nov 22, 2017
1,019
So,i have two signals to the receiver coil and i must to block the one from transmmiter and to boost the other from the reflection.
Use for receiver two identical coils L2 and L3, mounted side by side.
Connect coils in series in polarity, shown on picture below.
Slightly change orientation of one coil for full elimination of transmitter's signal.
That's it.
1609801977323.png
 

DickCappels

Joined Aug 21, 2008
6,776
Alternatively switch to very short pulses, less than a nanosecond in width and transmit one pulse at a time, then giving enough time for the return signal to return you may transmit another pulse. There are tricks you can use with these pulses depending upon your objectives.
 

Danko

Joined Nov 22, 2017
1,019
Hello!I have a construction with two coils,of a transmitter and a receiver one next to the other and at a distance of 1 meter between them.
So VARIANT 1 is yours.
Danko you mean two receiving coils like the picture below?
1609814154962.png
It is VARIANT 2.
Used when transmitter coil L1 and receiver coil L2 are in the same location.

1609813528776.png

Attached Microsoft Visio file Coils.vsd
 

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