![]() The chamfer is taking into account by the following expression: In these formulas, the dimensions r o, r i, h e are in millimeters, C 1 - mm -1, C 2 - mm -3. The effective factors of a toroidal core with a rectangular cross section are determined as follows: Effective cross-sectional area of the magnetic circuit A e.These are indicated by the suffix "e" added to the symbol. The dimensional parameters of that substitute toroid are called effective parameters. In this method, the original core is substituted by an ideal toroidal core such that a coil wound on that toroid would give exactly the same electrical performance and with same number of turns as the original coil. The method for calculating magnetic core coils, which is standard, is recommended for use by the International Magnetic Association in IEC Publication 205, “Calculation of Effective Parameters of Magnetic Piece Parts”. μ r - relative magnetic permeability of the core.In a simplified form, with the dimensions of the core in millimeters and the inductance in micro-Henry, the equation looks like this: I - the value of current through the coil.μ r - actual relative magnetic permeability of the core.The signs in the formulas correspond to the following diagram of a toroidal ferrite core: We divide this area into infinitely thin segments of height h at a distance r from the axis and sum these segments by integrating over the radius:įurther, in accordance with the definition of inductance, we arrive at the following expression: The magnetic flux through the cross-sectional area of the core can be calculated as follows. In accordance with the Ampere's Law, we can calculate the magnetic flux density in the core at an arbitrary distance r from its central axis. We can find the formula for the inductance of a rectangular cross-section toroidal coil step by step based on fundamental laws of electromagnetism. Inductance calculation of a ferrite toroid coil Ferrite core inductor at radio frequency.Multilayer air core inductor on a rectangular form.Self-capacitance of single-layer inductor.Features of calculation of power supply chokes.How to calculate single layer LC-circuit coil in Coil64?.Usually, the power density is measured in mW/cm2. The power density at a distant point (R) from a practical antenna with a gain of G is the power density from an isotropic antenna multiplied by the practical antenna gain. The gain (G) of the practical antenna represents the maximum radiation intensity in a given direction (or absorbs incident power from that direction) when compared with a theoretical isotropic antenna. R = Distance to the center of the antenna (i.e., radius of the sphere) Where, P = Transmitted power/power input in Watts Power density from an isotropic antenna (at distance R) P D = P / 4πR2 The power density at a distance “R” from an isotropic antenna is defined as the ratio of the transmitted power to the surface area of a sphere (4πR2) at that distance. Unit of power density is usually represented in mW/cm2.Īn isotropic antenna is a theoretical antenna (i.e., practically not exist) that would radiate out RF waves equally in all directions with the same intensity. In other words, power density can also be defined as the product of the power density of an isotropic antenna and its gain. The space can be represented as a sphere having a radius “R” (distance from the center of the antenna). The power density of an antenna is the measure of power/square cm (in space) from the center of the antenna.
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