Very large DD coil

[dbanner]

I would try super D geometric pattern first. Just scale up from 19 inches to 38 inches. Then cut out pattern and place on board with nails to wind coils. Both Rx coils will have same number of turns. Aim for your target inductances and use coil calculator to approximate no. Of turns. You can tune the coils to correct resonance so that at null, phases will be correct.

[Krzychu_]

Coils are large and interact with each other on a long length and surface, and in addition must be electritically shielded. The fluxes of the variable electromagnetic field of both coils must be compensated and the entire system must have an appropriate phase of response for proper operation of identification and discrimination. Arrangement from the point of view of geometry seems simple, because symmetrical, but, to obtain this symmetry may prove to be the most difficult problem to solve ... It remains to experiment in the absence of external disruptions, that is in the field, outside the city.

[dbanner]

They can then be tightened in place with plastic nut an bolts together with glue. If you want to try different Rx coil then all you have to do is disassemble from slide. This makes easier for experimenting with different coils for Rx.

[dbanner]

Cut grooves in ply along for each Rx will slide along perpendicular axis to tx coil. This make easy to fix null position

[dbanner]

For easy nulling I suggest you pot the Rx coils independent of each other in their own respective housing which can be rigged with a slide mechanism to easily
adjust its null position with respect to tx coils.

[dbanner]

Your design looks interesting, where did you get the idea from? It looks somewhat like the gpz 19 inch super D coil shape. Bigger coil bigger EMI effect. Required very good shielding.

[Krzychu_]

OK, I intend to finish the transmission winding and pour it over the resin without electrostatic shielding, while the RX receiving winding pre-position and check the correctness of identification and discrimination. It's hard to predict the effect of the electrostatic screen on their final, mutual location. When balancing the coils, I will have to leave part of the loose section of the windings to correct their compensation

[kt315]

Kr_

we do not have the experts here on big ramified coils to say you more. no data. i can give some recommendations and thas all.
in my opinion you do not have to strengthen the windings in all constructive and have to test at first as temporary one.
after getting good result then gather them and glue together.

[dbanner]

Then for capacitance issue, well ok, make sense. So you are not making big capacitance.
My shock absorber theory was rubbish then.

[Krzychu_]

Thanx!
I plan to make two RX windings on both sides of the TX transmit coil connected with antiparallel. This will be a simple system for verifying false signals from the coil excitation. I will consider single signals to be false, and double signals to be correct. Is it good idea?

[kt315]

see a table on right https://en.wikipedia.org/wiki/Relative_permittivity

look vacuum vs air RPs.

[kt315]

Yes, it is for isolation from vibration at a certain frequency being transferred to coil. The rope acts like shock absorber.

not. not vibration. we say again about ε_r --- is the relative static permittivity (sometimes called the dielectric constant) of the material between the plates (for a vacuum, ε_r = 1);

look https://en.wikipedia.org/wiki/Capacitance

As a quantitative example consider the capacitance of a capacitor constructed of two parallel plates both of area A separated by a distance d. If d is sufficiently small with respect to the smallest chord of A, there holds, to a high level of accuracy:C=ε rε 0Ad{\displaystyle \ C=\varepsilon _{r}\varepsilon _{0}{\frac {A}{d}}}

[dbanner]

I can't say for sure,but tiny movements across such a long axis is amplified, and could affect the coil.

[dbanner]

OK, thanks for the advice. Did I understand correctly that enameled wire should be wrapped with a wide rope or tape? Is it because the coil so made does not transfer vibrations, tension and other unwanted effects from the resin to the windings?

Yes, it is for isolation from vibration at a certain frequency being transferred to coil. The rope acts like shock absorber.

[Krzychu_]

OK, thanks for the advice. Did I understand correctly that enameled wire should be wrapped with a wide rope or tape? Is it because the coil so made does not transfer vibrations, tension and other unwanted effects from the resin to the windings?