In our previous blog post, we talked about the importance of antenna design and testing. This time we are delving more deeply into antenna simulations: why are they at the core of cost-effective business?

Developing electronic devices is always expensive and time-consuming, and wireless products are no exception. The consequences of choosing an inadequate antenna can render even months of development time worthless.

As stated, our previous blog post dealt with antenna testing in the R&D process. This time we wanted to highlight an even earlier stage of the process: simulations. Actual antenna testing should only come after antenna simulations. Why?

Well, in order to even test an antenna, there needs to be a prototype to test, which means that significant investments have already been used. If everything worked out perfectly all the time, this wouldn’t be problem. Unfortunately the selected antenna solutions often fall short of expectations. There is, however, a way to mitigate this risk and eliminate the need to gamble with precious R&D investments: antenna simulations.

The Phases of Simulation-Driven Antenna Design Process

The four phases of simulation-driven design process.

The fundamental logic behind the simulation-driven design is the ability to verify all design choices with simulations, while the product design evolves. The antenna design process divides into four phases: pre-study, concepting, antenna integration and verification. All phases involve close collaboration with the product development team.

1. Pre-Study: Starting Out with Innovative Concepts

The simulation-driven design process starts with the pre-study phase. During this phase, explorations of initial product ideas happen before any mechanical models exist. This phase is also referred to as “pre-concepting”. The antenna engineers run sets of simulations using simplified models, to provide input into what is achievable. These simplified models are based on the desired size of the device, use case, PBC size, materials and target specification. The results we get from these simulations then inform the product management team on how to refine the specifications of the product.

2. Concepting: Shaping the Optimal Antenna Solution

Once the product has a target specification, the concepting phase begins. During the concepting phase, antenna engineers test and develop various antenna solutions, using simulations with the latest CAD models available. We iterate and continue this phase, until one antenna concept has been singled out. It’s necessary that at this phase, the overall design has matured enough, so that any subsequent changes won’t affect the antenna concept selection.

3. Antenna Integration: Merging Elements

After selecting the antenna concept, it’s optimized for the current product design. A series of simulations are performed to assess the effects of mechanical and PCB layout changes. These simulations help identify unwanted resonances that are either on useful frequencies or have a risk of tuning in the final product. Professional engineers anticipate these risks early, so that fixes can be prepared adequately in advance. At this phase, EMC specialists also help with ground connections and floating.

The antenna integration phase concludes with an extensive simulation round, known as virtual antenna testing. Virtual antenna testing is conducted only for product designs that are ready to be released for prototyping. The design is modelled in an extremely detailed way to give as accurate results as possible.

4. Verification: Confirming Accuracy

Verification by measurement is always necessary, no matter how accurate the simulations might be. This approach ensures that all of the inputs for the simulation – such as materials and component models – have been correct. It also eliminates any possible human errors. If you want to learn about antenna measurements in detail, you can read our previously mentioned blog post.

Comparison between Antenna Simulation and Measurement

With this kind of simulation-driven design, accuracy is the critical foundation that everything relies on. To demonstrate the accuracy of antenna simulations provided by Radientum, we are going to do a little test run! Let’s take a closer look at a commercial multiband LTE antenna, that covers frequencies at 698-960 MHz and 1710-2690 MHz. The modeling and utilization of the chip antenna followed the reference design provided by the antenna supplier.

Simulation model of the chip antenna and reference PCB.

In the picture above, you can see the simulation model of the chip antenna and the reference PCB. We’ve hidden model details due to confidentiality. On the test run, we first measured simulated results, and afterwards made passive measurements with passive measurement tools. The reference board purchased from the chip manufacturer underwent simulated measurements, while the passive measurement took place in our anechoic chamber at the Radientum laboratory.

Matching levels (S11) for simulated and measured results.
Total antenna efficiency for simulated and measured results.

The results in Figure 1 show matching levels (S11) for both simulated and measured results. Figure 2 illustrates the total efficiency of the antenna. LTE bands are highlighted in both figures with a horizontal black line. The light curve shows the simulated results, while the dark curve shows the measured ones.

As you can see, the curves in Figure 1 align nicely, with only minor differences. This indicates how closely the simulated result matches the measured one. In Figure 2, the measured and the simulated results of the total antenna efficiency differ slightly. These are expected extra losses in real-life measurements. No need to worry: these are exactly the kinds of problems that we consider during the antenna design process.

Improving the Cost-Effectiveness of R&D

So, what did we learn today? As demonstrated, professional antenna simulations are able to predict final performance very accurately, without the need for numerous expensive prototypes. We used a commercial chip antenna in our example, but you can expect similar results for any antenna, whether it be off-the-shelf, or custom made; PBC trace or Chip; Flex or Ceramic. The type, shape or model doesn’t matter, simulations offer a cost-effective way to get precise and verified results for every antenna.

Just a little while ago, simulation-driven antenna design was a privilege that only relatively few multinational corporations and antenna manufacturers could afford. Thanks to the recent technological advancements, these tools are now available for companies and projects of all sizes. If you’d like to know more about our services regarding antenna simulations, our team would be happy to help you!

This post is a revised version of an older blog post. Revision written by Matias Puro.

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