Example 12: Raspberry Pi Model 3B+ Antenna Evaluation

This antenna example is a common and popular option for most IoT devices operating in the 2.45 GHz “WiFi” ISM band. It is a PCB antenna designed by Proant AB and replaces the dielectric SMT chip antenna previously used the “Pi’s”. The design is a planar resonant cavity using two sets of SMT capacitors to setup resonances in the 2450 and 5800 MHz WiFi ISM bands.

While small antennas are convenient and often inexpensive, they compromise performance for their size trade-off. This example antenna evaluation will show the actual radiation efficiency vs frequency for this tiny antenna, as well as it’s 3D gain patterns. Since the test results are swept from 2 to 7 GHz, we also present our 4-Dimensional plots, where frequency is swept with time so that customers can visualize hundreds of 3D patterns in an animation. Video players also allow customers to “scrub” back and forth in their video viewer to see specific frequencies of interest.

Test results indicate the radiation efficiency in the 2.45 GHz WiFi band is quite good with an average gain of -2 dBi or 60%. In the 5.5 GHz WiFi band this drops to about -3 dBi or 50% efficiency. In our experience, these are both very good for such a small and inexpensive antenna. A graph of return loss is also available here.

The Excel spreadsheet with gain data and graphs may be downloaded HERE.

The 3D plotfile may be downloaded HERE and used with our 3D Plotting Software.