Automating antenna impedance characterization with Connect

Nominal Connect offers custom applications for RF engineers to coordinate, calibrate, and save test runs

What is antenna matching?

Antennas have become ubiquitous in modern technology, serving a vital role in the transmission and reception of RF signals across a diverse set of applications. Their influence ranges from the cell phones we carry in our pockets to the missile defense radars that line our coasts. Antennas are critical hardware components that require extensive test and validation campaigns.

Impedance matching is an important part of the antenna design and test process that ensures the antenna performs with maximum efficiency within the desired frequency ranges. For RF test engineers, antenna characterization can be an involved and difficult process, as it requires repeated calibrations, measurements, and analysis with benchtop instruments such as a Vector Network Analyzer (VNA). As antenna production continues to grow, test engineers are forced to perform tedious, critical testing – again and again and again.

That’s where Nominal Connect comes in.

Nominal Connect: The single platform for antenna benchtop instruments

Nominal Connect provides test engineers with a single platform that centralizes all of the data and software necessary to calibrate and command benchtop instruments, gather measurements in real-time, plot and analyze key insights, and save and share test data across teams. With Connect’s Python-first SDK, engineers can take advantage of open-source instrumentation libraries such as PyVISA to easily communicate with numerous benchtop instruments.

In the case of impedance characterization, in less than 30 lines of Python code, an engineer can::

• Establish connection to a VNA

• Set sweep parameters (bandwidth, start/stop frequency, power level, point count)

• Run a frequency sweep

• Measure and return S-parameters of the device-under-test (DUT)

Nominal Connect also offers real-time visualization and customizable GUIs, enabling quick and easy development of applications with streamlined interfaces for loading and saving files, displaying key measurements and statistics, and remotely commanding instruments.

For example, an RF test engineer looking to streamline antenna impedance characterization can use Connect’s low-code platform to build an application to load VNA calibration files, input desired VNA sweep parameters, run a frequency sweep, visualize the S11 magnitude/phase curves and Smith Chart, and save the measurements to a CSV or Touchstone file.

Re-usable calibration files

Every engineer that has used a VNA to test RF devices and networks understands the importance of calibration for removing systematic errors. To avoid spending time re-calibrating the instrument, engineers can save calibration files which contain the systematic errors measured from a previous calibration process. Connect’s framework enables engineers to easily load calibration files and avoid wasting time re-calibrating the instrument.

Setting parameters and running the sweep

Primary parameters for a VNA sweep include:

• Start frequency: the beginning frequency of the sweep

• Stop frequency: the final frequency of the sweep

• Point count: the number of discrete frequency steps within the sweep range

• Power level: the power level of the VNA source signal

• Bandwidth: the bandwidth of the intermediate frequency (IF) filter

With Connect’s framework, an engineer can build a simple and intuitive interface that allows users to input values for these parameters and send commands to configure the VNA accordingly. No need to rewrite messy config files every time you want to run a sweep, just input the desired values and click “Run Sweep.” Connect’s real-time visualization will show you the measurements and give results immediately.

Saving results

Once a run is complete, an engineer can easily save the collected measurements to a CSV or Touchstone file, documenting the results of the test and making the data accessible, queryable, and shareable.

Nominal Connect handles the data;
RF engineers focus on the mission

By building an application in Nominal Connect that streamlines much of the antenna impedance matching process, an RF test engineer can save several hours of time spent on troubleshooting and debugging test automation scripts and instead focus on collecting measurements, drawing insights, and sharing results – to build at scale, faster.