• 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

Design of Circularly Polarized Patch Antennas

A reader is a radio frequency (RF) transmitter and receiver, controlled by a microprocessor or digital signal processor. The reader, using an attached antenna, captures data from tags then passes the data to a computer for processing. Here the design flow of a patch RFID-antenna for frequency range: 908.5 - 914 MHz (RFID band of Korea) using CST MICROWAVE STUDIO® (CST MWS) is described. This article is published with the permission and courtesy of Prof. Bierng-Chearl Ahn and his colleagues at Chungbuk University, Korea.

Figure 1 shows the proposed structure of the antenna and the design parameters.



Figure 1: Design parameters of RFID-antenna

The design parameters define the operation and the performance of the antenna. The operating frequency determines the size of the patch antenna: W ≈ L = 0.4 λ, while truncation t / W, as well as vertical height of the ground plane, the axial ratio. The ground plane size controls the gain of the antenna while the distance between ground plane and the patch affects the bandwidth. On the other hand, the size of the feed gap influences the impedance matching. The geometry was drawn and the parameters of the antenna optimized through simulations performed in CST MWS. Figure 2 shows the CST MWS model of the patch antenna, the final design parameters and the manufactured antenna. ...



Figure 2: The geometry of the patch antenna seen in CST MWS together with fabricated one

 

The measurements were made and compared with the simulations. The plots of the reflection coefficient and the gain are shown in Figure 3. It can be seen that the measurement results agree with the simulations very well.

Figure 3: Comparison results between measured and simulated values; All simulations were performed in CST MWS

The patch antenna was further miniaturized by placing dielectric material between the patch and the ground. The simulated and consequently fabricated miniaturized antenna can be seen in Figure 4 with the final design parameters.



Figure 4: RFID patch antenna miniaturized by dielectric loading

The simulations are compared to the measurements in Figure 5. It can be seen that with the dielectric between patch and the ground, the better resonance at frequency of 900 MHz can be achieved.



Figure 5: Simulation and measurement results for the antenna with dielectric

 

As the last step the gain was increased via designing 2-Element SFADP Array. First, the distance between elements was optimized using CST MWS in order to obtain maximum gain. After that the feeding network and power divider circuit (Figure 6) were designed.

Figure 6: Feeding network and power divider

The antenna array was manufactured and measured. The comparison plots between measurements and simulations can be seen in Figure 7 and 8.



Figure 7: Performance of the designed antenna


Figure 8: Performance of the designed antenna: axial ratio

In this article three RFID reader antennas were designed using CST MWS. Measurements of the fabricated antennas show good agreement with simulated results.

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.