# Magnetic Communication Using High-Sensitivity Magnetic Field Detectors
## 4 Conclusions and Outlook  
In this contribution, an innovative approach for magnetic communication is considered. The key idea is to employ a high-sensitivity wideband magnetic field sensor at the receiver side. Several advantages have been indicated compared to conventional MI coil-to-coil communication, because a different measurement principle is used compared to a receiver coil. In most of our numerical results an AMR sensor is assumed. AMR receivers are extremely small, so that they can be considered to be a point sink. Given the same form factor, they are much more sensitive  
\begin{table}
\begin{tabular}{l l l l} \hline \hline
**Material** & \(\mu\) & \(\mu_{\text{r}}\) & \(B_{\text{s}}\) \\ \hline Air & \(1.2566\times 10^{-6}\) H/m & \(\approx\)1 & no saturation \\ Nickel & \(1.25\times 10^{-4}\) H/m & \(\approx\)100 & 0.3–0.5 T \\ Ferrite & \(>\)8 \(\times\) 10\({}^{-4}\) H/m & \(>\)640 & 0.3–0.5 T \\ Electrical steel & \(5\times 10^{-3}\) H/m & \(\approx\)4000 & 1.5–1.8 T \\ Permalloy & \(10^{-2}\) H/m & \(\approx\)8000 & 0.66–0.82 T \\ mu-Metal & \(\approx\)2.5 \(\times\) 10\({}^{-2}\) H/m & \(\approx\)20,000 & 0.65–0.82 T \\ \hline \hline \end{tabular}
\end{table}
Table 3: Magnetic permeability \(\mu\) in Henries per meter, relative permeability \(\mu_{\text{r}}\) and saturation flux density \(B_{\text{s}}\) in tesla for different materials. For \(\mu\) and \(\mu_{\text{r}}\) the initial permeability of the respective core material is given in the table [16; 19; 20].  
Figure 7: Transmission range as a function of the magnetic field detection limit of the detector. Parameters are taken from Table 2. The maximum transmission distance based on the prototype implementation detection threshold is marked for three different bandwidths. The transmission range can be increased by using a more sensitive type of detector.  
than coils. This enables longer transmitting distances for mobile applications, where small receiver sizes are necessary. The frequency characteristic of AMR sensors is almost flat below the cut-off frequency. This feature together with the small size is of great interest for multiple-input single-output (MISO) system approaches. Vice versa, single-input multiple-output (SIMO) processing can be used for sensitivity improvements. Some AMR detectors include 3D functionality. This aspect is useful for joint communication and localization purposes. Possibly, the data rate can be enhanced by 3D processing. Moreover, a high permeability transmitter core material can be used for coil-to-AMR communication to extend the possible range drastically. Our investigation demonstrates that magnetic field communication with an AMR receiver is a promising technique for mobile applications in challenging environments. Since the effective transmission distance is a function of the sensitivity of the detectors, the fundamental observations of this paper can be exported to other measurement principles. For example, the AMR sensor used in our prototype receiver could be replaced by a fluxgate sensor.  
Conceptualization, Experiments, Analysis, Writing-Original by [PERSON]; Conceptualization, Supervision, Writing-Review and Edition by [PERSON]; Conceptualization and Writing-Review by [PERSON]. This research received no external funding. The authors would like to thank Sensitec GmbH for providing AMR sensor samples. The authors declare no conflict of interest. The authors declare no conflict of interest.