PCB Antenna for STM32WB shown in AN5129 Application note where used pcb stack-up with core 711.2 μm. Exactly the same antenna used in P-NUCLEO-WB55 (MB1355) where pcb thickness is ~1500 μm. How is it possible?

[Shamrel]

Hello! PCB Antenna for STM32WB shown in AN5129 Application note where used pcb stack-up with core 711.2 μm. Exactly the same antenna used in P-NUCLEO-WB55 (MB1355) where pcb thickness is ~1500 μm. How is it possible? How changes antenna parameters when thickness substrate is increased?

In AN5129 written: "The electrical parameters and performance of the PCB antenna are also determined by the substrate used, in

particular the thickness of the core and dielectric constants." But in AN5165 recommends to use this solution for different stack-up. How is it possible?

[Remi QUINTIN]

This part only concerns the 50 ohm track between filter / matching and antenna.

The AN was made for a 0.8mm PCB.

Of course, if the PCB is 1.5mm, you have to recalculate the width of the 50 ohm track (only).

For the antenna, or there is no GND on bottom side,

The width of the antenna track remains the same.

Between 0.7 and 1.5 mm of FR4, it did not change the impedance nor the performance of the antenna.