NFC Antenna Tool - v1.1.0 User Manual

This is the online user manual for the software “NFC Antenna Tool” version v1.1.0. NFC Antenna Tool can be used to calculate antenna parameters for Renesas NFC products.

This user manual is provided in English only. For assistance in other languages please either use your browser’s translation engine or contact your local Renesas representative.

Features

The software has been tested on following platforms and operating systems:

  • Windows 11 x86 64-bit

    • Edge

    • Chrome

  • Ubuntu 24.04 LTS x86 64-bit

    • Firefox

    • Chromium

  • Android 15

    • Edge

    • Chrome

Other operating system versions supported by abovementioned web browsers may work too but were not subject to testing. Note that to enter decimal number either the dot or the comma separator can be used, depending on the operating system and browser’s language settings.

The main application features are:

  • Matching Calculation

    • calculating the values of the antenna matching circuit based on:

      • L Antenna [nH]

      • R Antenna [Ohm]

      • Antenna Self Resonance [MHz]

      • Product properties

      • Cs_IC [pF] (constant defined by product properties)

      • R_dr [Ohm] (constant defined by product properties)

      • Target Impedance

      • Target System Q factor

    • calculated values

      • Q Antenna

      • Cs

      • Cp_se

      • cp_diff

      • Rp_se_ext

  • Coil Calculation

    • calculating certain antenna properties based on:

      • coil outer dimensions

        • a

        • b

      • w - track width

      • g - gap between traces

      • N - number of turns

      • t - track thickness (constant)

    • calculated values:

      • L Antenna [nH]

      • R Antenna [Ohm]

      • Q Antenna

      • Free Coil Area

Installation Notes

This application is web-based and does not require any additional installation procedure. However, for offline-use and for faster access the application it can be installed on the local device via the Google Play Store or by using the following installation instruction.

Installation steps for Chrome and Microsoft Edge browsers:

  1. Open the NFC Antenna Tool.

  2. Look at the right side of the address bar, you will see an install icon (Chrome: a small computer screen with an arrow icon, Microsoft Edge: three boxes with a “+” icon).

  3. Click the install icon.

  4. A confirmation dialog will appear. Click Install.

Alternatively the installation procedure can also be started using the Install button at the bottom of the left-side menu.

There will be no install icon if you already have the application installed.

Updates and offline availability

When installing the application one specific version of it gets installed. A toast message is popping up on application start in case a new version is available. To switch to the newer version use the combo-box next to the application title in the top bar. Selecting the new version number will switch to that version. When restarting the application the recently used version will be opened by default. It is possible any previously visited application version also when being not connected to the internet. Opening the version combo-box will list and mark such versions as AVAILABLE OFFLINE.

Graphical User Interface

To start the NFC Antenna Tool on Windows, open the tool in a browser Tab. For offline-users, just open the downloaded App.

The menu bar on the left-hand side offers two main functionalities, these are the Coil Calculation and the Matching Calculation. In these tabs, all calculations are triggered automatically on any change of an input.

At the bottom of the menu bar the menu item Get Support will redirect to the community forum for NFC enabling users to request help by the NFC customer support team.

Coil Calculation

When designing your personalised solution, it is recommended to start with the Coil Calculation, as resulting characteristics of the antenna are required for the Matching Calculation. Examples for these would be the antennas inductance and resonant frequency.

To start, set the available Area for the desired antenna, by changing the outer dimensions a and b.

The track thickness of the PCB has minor impact to the calculation. For that reason a default value of 0.035mm is used and there is no input control available for it.

After having set the antennas Area, a goal inductance should be set depending on the application. A general recommendation for IoT applications is 900nH ±10% and for behind display applications it should be 600nH ±10%. For other applications, please contact your local Renesas representative to assist in choosing the most appropriate value.

To achieve the desired inductance the track width w, the gap g and the number of turns N have to be adjusted.

  • By increasing w the inductance strongly decreases.

  • By increasing g the inductance decreases.

  • By increasing N the inductance strongly increases.

This approach is only valid in free air applications (conductive free surrounding). The minimum distance between the antenna and conductive materials should be larger than 10mm. Avoid conductive closed loops around the antenna.

In case of the presence of conductive materials near the coil, the use of ferrite sheets is recommended. Ferried sheets generally increase the inductance of the coil and lower the quality factor, thus increasing losses.

Matching Calculation

Now that the values of the antenna have been set, the matching calculations can be done.

To start input the previously calculated inductance of the antenna L Antenna. R Antenna and Antenna Self Resonance have to be measured with a Vector Network Analyzer that is hooked up to the antenna.

Then the correct product name has to be selected, because of their different Cs_IC and R_dr.

Lastly the Target Impedance has to be chosen. Target impedance changes the power of the antenna based on the following formula: P_rms = V^2/ 2*impedance (V is fixed and is set by the product being used) and P_rms is directly proportional to the read distance of the antenna. The antenna size is also directly proportional to the read distance of the antenna.

Save Results

A feature of this tool is that it is able to save the input values in the browsers cache. Thus, closing the tool does not loose data.

If needed it is possible to reset the editable values to their defaults. To do that the circular arrow in the upper right corner, has to be clicked. After confirming your action in the popup window, the resetting will be complete.

Exporting of result values is not supported.

About view

This view provides some legal information as well as the list of used 3rd party software licenses.

Release Notes

This chapter contains the release notes for the NFC Antenna Tool v1.1.0.

Release Data

Software

NFC Antenna Tool

Software Release Date

25-09-2025

Software Version Number

v1.1.0

Software Versioning Rules

This describes the software version numbers and does not apply to documentation version numbers (as found in the footer of this document).

Each software version number string consists of three numbers: MAJOR. MINOR. HOTFIX. Software version numbering is implemented according to https://semver.org.

Given a version number MAJOR.MINOR.PATCH, increment the:

  • MAJOR version when the major version number of the integrated SDK has increased so that both major version numbers are equal.

  • MINOR version when you add functionality in a backward compatible manner.

  • PATCH version when you make backward compatible bug fixes.

Changelog

  • Added product type PTX205R to matching calculation

  • Optimized app icon for various operating system icon border styles

  • [Android] Close keyboard automatically after last input field completed

Known Issues

Known issues and limitations of the application can be found at the Known issues and limitations page.