Mobile Phone in Vicinity of Human Head - SAR calculation

In modern times, due to the increased integration of electronic devices into everyday life, it has become imperative to calculate the impact of electronic devices on the human body. In this white paper we will simulate the effects of a mobile phone on a human head at 1.8 GHz.

WIPL-D Software suite offers a great set of tools for general 3D electromagnetic (EM) simulation of real life geometries. WIPL-D Pro CAD enables import of extremely complex and versatile geometries from all popular CAD files. This product also includes an in-house developed mesher which performs subdivision of complex geometries into generalized quadrilaterals which serve as input for numerical kernel. The meshing is automated and extremely efficient to allow precise modeling of details, curvatures and small features while the requirements for EM simulation are kept as minimal as possible.

After a proper quad mesh is created, WIPL-D Pro allows EM simulation in most efficient manner available among commercial tools. WIPL-D kernel allows mesh elements (quads) of size up to 2 wavelengths by 2 wavelengths due to its higher order basis functions (current expansion on mesh elements is a polynomial of 8th degree for 2 wavelengths edge). The number of unknown coefficients to be stored in the Method of Moments (MoM) matrix is minimal and it can be estimated as 30 unknown coefficients per lambda square for metallic surfaces, and 60 for dielectric surfaces.

PIFA antenna

Simulation capabilities of WIPL-D software suite will be demonstrated by simulating SAR in the human head, due to the influence of a mobile phone. The realistic model of human head with a mobile phone is imported in WIPPL-D Pro CAD through one of our many supported formats. Additionally, the tool offers full modeling capabilities and a built in quadrilateral mesher. The first building block in the model is the radiating part of the telephone, the PIFA antenna.

Meshed model is shown in Fig. 1, together with the internal structure of this simple antenna.

Figure 1. Meshed PIFA antenna model

Simulation is performed on a regular desktop PC configuration comprising of quad core i7 CPU, 4 GB of RAM, but also powered with Nvidia GeForce GTX GPU card. It requires 1,116 unknown coefficients in the MoM system matrix and simulation time is around 3 seconds per frequency.

Fig. 2 shows the calculated radiation pattern of the antenna.

Figure 2. PIFA antenna standalone radiation pattern

Mobile phone model

The second building block in the model is the full telephone model. The CAD model is shown in Fig. 3.

Figure 3. WIPL-D Pro CAD mobile phone model

Meshed model is shown in Fig. 4, together with some of the internal structure. The PIFA antenna is located inside the red ellipse.

Simulation is performed on the same hardware configuration as for PIFA antenna itself. It requires 21,832 unknown coefficients, yielding simulation time of around 3 minutes per frequency.

Figure 4. Meshed mobile phone model

The radiation pattern of the mobile phone is shown in Fig. 5.

Figure 5. Mobile phone radiation pattern

Human head model

Meshed model is shown in Fig. 6, together with some of the internal structure. In the same model we have very large and very small mesh elements, which yields minimum EM requirements for WIPL-D simulation and results in ultimate performances.

Figure 6. Meshed Human head model with mobile phone

On the same hardware configuration, simulation now requires 40,320 unknown coefficients and simulation time is around 17 minutes per frequency.

The full models radiation pattern is shown in Fig. 7.

Figure 7. Human head model with mobile phone radiation pattern

The SAR near field results are shown in Fig. 8.

Figure 8. Human head model with mobile phone Near Field

The SAR distribution results are shown in Fig. 9, for the average power of 0.125 W for the mobile device at 1.8 GHz

Figure 9. Human head model with mobile phone SAR

PDF application note

If you have a specific problem in mind and you are not sure if WIPL-D software can handle that problem, contact us. We will analyze your needs and try to help, and if our products satisfy your requirements, we will make you the best possible offer for purchase.