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How to increase the Q value of the coil

Release time:

2023-07-26 09:01

Quality factor Q is an important parameter reflecting the quality of the coil, improve the Q value of the coil, can be said to be one of the key points to pay attention to the winding coil. So, how to improve the Q value of the winding coil, the following specific methods:

(1) According to the operating frequency, the choice of coil wire

Work in the low-frequency inductor coil, generally used enameled wire and other insulated wire winding. Operating frequency is higher than tens of thousands of hertz, but lower than 2MHz circuit, the use of multi-stranded insulated wire winding coil, so that can effectively increase the surface area of the conductor, which can overcome the effect of skin effect, so that the Q value of the same cross-sectional area than the same single wire winding coil 30% -50% higher. In circuits with frequency higher than 2MHz, the inductor coil should be wound with a single thick wire, the diameter of the wire is generally 0.3mm-1.5mm. between the winding of the inductor coil, commonly used silver-plated copper wire winding to increase the conductivity of the wire surface. This is not suitable for multi-stranded wire winding, because multi-stranded insulated wire at high frequency, the coil insulation medium will cause additional loss, the effect is not as good as a single wire.

(2) Selection of high-quality coil skeleton, reduce dielectric loss

In higher frequency occasions, such as short-wave band, because of the ordinary coil skeleton, its dielectric loss increased significantly, therefore, should be selected using high-frequency dielectric materials, such as high-frequency porcelain, PTFE, polystyrene, etc. as a skeleton, and the use of inter-winding method winding.

(3) choose a reasonable size of the coil, can reduce losses

A certain outer diameter of the single-layer coil (φ20mm-30mm), when the winding length L and the ratio of the outer diameter D L / D = 0.7, its loss is minimized; a certain outer diameter of the multi-layer coil L / D = 0.2-0.5, with t / D = 0.25-0.1, its loss is minimized. The loss is also minimized when the winding thickness t, winding length L and outer diameter D satisfy 3t + 2L = D. Shielded coil, the L / D = 0.8-1.2 when the best.

4) Selection of a reasonable diameter of the shield

Shield, will increase the loss of the coil, so that the Q value is reduced, so the size of the shield should not be too small. However, the size of the shield is too large, will increase the volume, and therefore to select a reasonable shield diameter size.

When the shield diameter Ds and coil diameter D ratio to meet the following values that is Ds / D = 1.6-2.5, Q value is reduced by no more than 10%.

(5) the use of magnetic cores can make a significant reduction in the number of coil turns

The use of magnetic cores in the coil, reducing the number of turns of the coil, not only to reduce the resistance value of the coil, the Q value is favorable to improve, but also reduce the size of the coil.

(6) The coil diameter is appropriately chosen to reduce losses.

Under the possible conditions, the coil diameter is chosen to be larger, the volume increases a bit, which is conducive to reducing the loss of the coil. General receiver, single-layer coil diameter of 12mm-30mm; multi-layer coils take 6mm-13mm, but from the volume considerations, should not exceed the range of 20mm-25mm.

(7) Reduce the distribution capacitance of the winding coil

As far as possible to use no skeleton winding coil, or winding in the convex rib type skeleton coil, can reduce the distribution capacitance of 15% -20%; segmented winding method can reduce the distribution capacitance of multi-layer coils of 1/3 ~ l / 2. For multi-layer coils, the smaller the diameter D, the smaller the length of the winding L, or the greater the thickness of the winding t, then the smaller the distribution capacitance. It should be noted that the distributed capacitance of the coil after diffusion impregnation and sealing coating will increase by 20%-30%.

In short, winding coils, always improve the Q value, reduce losses, as the focus of consideration.