• Which Products are you interested in ?

    CST offers a wide range of EM simulation software to address design challenges across the electromagnetic spectrum, from static and low frequency to microwave and RF, for a range of applications, including EDA & electronics, EMC & EMI and charged particle dynamics.

  • CST STUDIO SUITE
  • CST EMC STUDIO
  • CST BOARDCHECK
  • Antenna Magus
  • IdEM
  • FEST3D
  • Optenni Lab
  • Looking for a Training, Workshop or eSeminar ?

    CST STUDIO SUITE® is being demonstrated at trade shows and workshops all over the world. Take a look at the list of conferences and exhibitions CST will be attending and get further information regarding CST workshops, eSeminars and training days.

  • TrainingsRegular training courses are held in CST's offices in Asia, Europe, and North America. Please check our trainings section for detail of trainings in all over the globe. Advance registration is normally required.

  • WorkshopsCST hosts workshops in multiple languages and in countries around the world. Workshops provide an opportunity to learn about specific applications and refresh your skills with experienced CST support staff. Make sure you visit our workshop section.

  • eSeminarsThroughout the year, CST simulation experts present eSeminars on the applications, features and usage of our software. You can also view past eSeminars by searching our archive and filtering for the markets or industries that interest you most.

  • Check our latest Events
  • Why create a MyCST Account ?

    A MyCST account may facilitate your access to many of the offerings on the CST website, for example the registration for eSeminars and the watching of eSeminars recordings, setting email preferences, and there is more functionality to come. It is required to participate in workshops and trainings.

  • Personal PreferencesAllows you to update your email preferences and areas of interest. It helps us to personalize your experience.

  • EventsSearch for events by location, industry and application. Once you are registered, you will be able to manage your registrations and check important details about your events. This section also provides you with a repository for Workshop & Training material.

  • LibraryYou can collect articles you find on the CST website to reference or read later by clicking on the “Add this article” button at the bottom of the article page.

  • Create Your Own Account
  • Need technical Support ?

    Customers can customize their accounts once they have completed the account creation process. This platform acts as vivid interface between CST and our customers.

    We therefore offer access to the latest Service Packs (including an automatic notification that a new Service Pack is available), a steadily growing database of Frequently Asked Questions (FAQs), Application Notes and Training Videos, as well as an individual FTP section for easy exchange of large files with our support team.

  • Do I need an Account?To access the Support Site a valid maintenance contract and a one-time registration is required.

    Please note that your Support login does not work for the MyCST account.

  • Get Support
  • How to request a Trial License ?

    Get your license in only three steps:

    1. Fill in the required fields in the contact form on the right and click "Send Us Your Request".

    2. Lean back and wait until one of our CST Experts contacts you.

    3. Enjoy a our trial license.

  • Student Edition

    Student Edition The CST STUDIO SUITE® Student Edition has been developed with the aim of introducing you to the world of electromagnetic simulation, making Maxwell’s equations easier to understand than ever. With this edition you have, bar some restrictions, access to our powerful visualization engine and some of the most advanced solvers of CST STUDIO SUITE.

    Student Edition

CST – Computer Simulation Technology

Sensitivity Computation of an Inductive Proximity Sensor

Proximity sensors enable, in a simple manner, the position, size and material of a metal target to be established. Such sensors have the ability to obtain absolute analog signals proportional to proximity and are compact, robust and reliable constructions. Inductive sensors consist of a coil embedded in an open magnetic circuit.

The coil’s properties such as complex impedance depend on the magnetic resistance of the circuit. Metallic targets in the vicinity of the sensor affect the magnetic circuit and change the impedance and quality factor of the coil. These relatively small variations are detected by electronic circuitry and converted into desired length units.



Figure 1: Cut-Away snapshot section through the sensor

The geometry of the sensor was imported via the CST STUDIO SUITE® STEP Interface (Figure 2). The coil, also imported, was simplified by a faceted representation. A target was added which was parameterized to allow a set of S-Parameters, and subsequently the input impedance, to be obtained as a function of distance to the sensor. ...



Figure 2: 3D Model of the inductive sensor imported through STEP

A second order tetra-based mesh was applied to the geometry (Figure 3) and the full wave frequency domain solver of CST MICROWAVE STUDIO® was used for solving the field problem.



Figure 3: Tetrahedral mesh representation of the 3D model

The field plots in Figures 4-6 show different configurations of sensor and target with respect to the magnetic flux and current densities.



Figure 4: Magnetic flux density including a 2.5 mm spaced metal target



Figure 5: Current density at a spaced target of 2.5 mm



Figure 6: Current density at the windings at 6 Mhz resonance

The complex impedance can be directly derived from the S-parameters shown in Figure 7 for R +jωL as a function of frequency, a resonance can be identified at 6 MHz.



Figure 7: Complex impedance as a function of frequency

The Q-Factor gives an indication of the effectiveness of the sensor in terms of the frequency (Figure 8). A measure of the sensitivity can be obtained by the following equations:



Figure 8: Q-Factor formulae

This Q- Sensitivity / Q-measure is shown in Figure 9. A good working point is in the area of 100kHz at which the Q-Sensitivity is maximum. A blind spot is also obtained at 300 kHz where the Q-factor remains constant and the target distance can not be  identified by the sensor.



Figure 9: Q-factor and Q-measure as a function of frequency

Finally, an equivalent of the sensor was derived for which the complex impedance was fitted over a wide range of frequencies.



Figure 10: Equivalent circuit representation and curve fitting of the impedance

This article has demonstrated how 3D EM field simulation in combination with S-Parameters and circuit optimization can be applied to the design and analysis of inductive proximity sensors.

Rate this Article

0 of 5 Stars
5 Stars
0%
4 Stars
0%
3 Stars
0%
2 Stars
0%
1 Stars
0%
contact support

Your session has expired. Redirecting you to the login page...

We use cookie to operate this website, improve its usability, personalize your experience, and track visits. By continuing to use this site, you are consenting to use of cookies. You have the possibility to manage the parameters and choose whether to accept certain cookies while on the site. For more information, please read our updated privacy policy


Cookie Management

When you browse our website, cookies are enabled by default and data may be read or stored locally on your device. You can set your preferences below:


Functional cookies

These cookies enable additional functionality like saving preferences, allowing social interactions and analyzing usage for site optimization.


Advertising cookies

These cookies enable us and third parties to serve ads that are relevant to your interests.