![measure distance between points in cst microwave studio measure distance between points in cst microwave studio](https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fs41598-021-91400-2/MediaObjects/41598_2021_91400_Fig1_HTML.png)
![measure distance between points in cst microwave studio measure distance between points in cst microwave studio](https://www.mdpi.com/applsci/applsci-11-05995/article_deploy/html/images/applsci-11-05995-g006.png)
For the first, the use of batteries presents issues in terms of periodic replacement which may require complex surgical procedures. This provides several advantages specially for applications involving implantable devices or devices that need to be hermetically sealed during operation. Wireless power systems transfer the energy without wire connection between a source and a load. The results showed that the equation presents good accuracy for geometric parameters that do not lead the solution of the elliptic integral of the first kind to infinity. The coupling coefficient is computed using CST Microwave Studio and compared to calculation and experimental results for two coils with an excitation signal of up to 10 MHz. A simple equation is derived from Neumann’s equation for mutual inductance, which is then used to calculate the coupling coefficient. In this paper, we analyze the coupling coefficient as a function of the distance between two planar and coaxial coils in wireless energy transfer systems. Although high efficiency can be achieved when the system is operating in a static state, it can drastically decrease if changes in the relative position and in the coupling coefficient between the coils occur.
![measure distance between points in cst microwave studio measure distance between points in cst microwave studio](https://media.springernature.com/full/springer-static/image/art%3A10.1038%2Fsrep09988/MediaObjects/41598_2015_Article_BFsrep09988_Fig1_HTML.jpg)
In this scope, inductive links have been widely studied as a way of implementing these systems. In wireless energy transfer systems, the energy is transferred from a power source to an electrical load without the need of physical connections.