Is a flat spiral coil better for a PI detector?

[MDfanatic]

What are your thoughts on flat spiral coils? Are they better than a typical DIY coil for a PI detector?
I've been thinking about constructing a flat spiral coil (50cm) but I'm not sure if it's worth the effort.

Would I gain anything in sensitivity or depth or is the difference neglectible?

[kt315]

nikola tesla coil?

[MDfanatic]

Yes but with 55cm opening in inner diameter.

[lucifer]

Flat spiral coils have less parasitic capacitance which could allow for earlier sampling and increased sensitivity to small gold. On the other hand, coil's inductance is also somewhat lower due to the spacing between turns and you might get slightly less depth.

[MDfanatic]

Well I'm not looking for small gold, I'm looking for medium and big size targets (like a cache) at depths of 1 - 1.5 meters.

That's where I'm confused, theoretically a lower inductance coil (50cm 300-350uH) would be better for my application (i.e a cache at 1 - 1.5m deep) so (in theory) a flat spiral coil would be better in terms of sensitivity.
But that's just my lucky guess as I don't have a testing field or the tools to make a coil winding jig to test different coils.

[Carl-NC]

Sounds like you don't need an aggressively short delay, so a spiral coil won't help. A low inductance coil is also not necessary.

[MDfanatic]

Thank you Carl for your input, I guess I'm better with the classic hand wound coil.