General Questions to PI Coils and their construction

[GeoMax]

Hello Forum,

I have some general questions regarding PI coils and construction.

1) Mono Coil
The mono coil is lying flat on the floor. How should be the winding direction of a mono coil in respect to the ground (the floor)? Clockwise or counter clockwise?

2) Frame Coil
Is it the same as with Mono Coils?

3) Coil with separate RX and TX Coils
Both coils are lying flat on the floor. The RX coil is smaller and located within the TX coil. How should be the winding direction of the two coils in respect to the ground (the floor)?
RX = Clockwise or counter clockwise?
TX = Clockwise or counter clockwise?

4) DD Coil
Both coils RX and TX are lying flat overlapping on the floor. How should be the winding direction of the two coils in respect to the ground (the floor)?
RX = Clockwise or counter clockwise?
TX = Clockwise or counter clockwise?

5) Dual Field Mono Coil
Both coils are connected in series and lying flat on the floor. The RX coil is smaller and located within the TX coil. How should be the winding direction of the two coils in respect to the ground (the floor)?
Outer coil = Clockwise or counter clockwise?
Inner coil = Clockwise or counter clockwise?

6) Coils for probing boreholes
What is the correct name for it and how is their construction? Does someone have a drawing or a construction information?


Thanks in advance for your answers.

[Carl-NC]

1. Doesn't matter. You'll see the same RX signal regardless.

2. Ditto.

3. What matters is whether they are wound in the same direction or opposite. And it only matters in the polarity of the RX signal, which is part of the overall system design. So there is no right answer until you design the whole system. When it comes to IB coils I like to wind them such that the RX voltage is in-phase with the TX voltage, it just makes things consistent and easy to remember. For this, you set the windings in opposite directions. Keep in mind if you get it wrong, you just flip one of the coils upside-down, or reverse its leads.

4. Ditto.

5. They just need to be wound in the same direction.

6. Not sure what kind of coil is used for boreholes. What is it trying to detect?