Boost stm32wl5moc lora range

[shreyaschandran]

Hi,

I'm working with LoRa on STM32WL5MOC for a custom board and comparing performance with the dev board. I've measured RSSI and SNR at different distances.

- Custom board vs Dev board RSSI, SNR values are noted for reference.

How do I improve the custom board's RSSI? Are there specific design or config tweaks (like antenna matching, RF switch, etc.) to boost it? Using STM32WL5MOC reference for the custom board.

Any insights would help!

Thanks

[Andrew Neil]

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@shreyaschandran wrote:

How do I improve the custom board's RSSI?

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As we know nothing about your board, it's impossible to say!

You'd need to show your schematic and layout, and details of what antenna you're using.

Some good, clear photos would also help.

How to write your question to maximize your chances to find a solution

[shreyaschandran]

Thanks for the response. We're using the same schematic as the dev board for the custom board. We're also using a 3dB antenna for LoRa transmission.

Is there anything else needed to troubleshoot the RSSI issue in dev board as well?

[Andrew Neil]

At RF, the layout is critical - the schematic alone is not sufficient.

Also, please give full details of the antenna, and how it is connected.

Again, Some good, clear photos would help

[shreyaschandran]

Hi,

Thank you for your feedback. We understand that at RF frequencies the PCB layout is critical and that the schematic alone is not sufficient for analysis.

As requested, we have attached:

The LoRa RF schematic section

Screenshots of the PCB routing for the LoRa RF path (from the transceiver to the antenna matching network and antenna connector)

Antenna Details

Antenna type: External LoRa antenna

Frequency band: 865–867 MHz

Impedance: 50 ohms

Connection: U.FL connector connected directly to the RF output through the matching network

Matching network: Pi-network placed close to the RF pin, as per reference design guidelines

The RF trace is routed as a controlled-impedance 50-ohm microstrip with a continuous ground reference and via stitching around the RF path.

In addition to the custom board, we would also like to clarify one point regarding the observed RSSI issue.

We are seeing lower-than-expected RSSI values, and we would like to confirm whether this behavior is also expected or observable on the corresponding ST reference / development board under the same test conditions, or if it is likely specific to our custom hardware.

Looking forward to your guidance.