QUESTION

Question

Hello all! Do I need to have the gnd plane only on the bottom of the IC on every layer (my stackup is gnd, 3v3, gnd, gnd), or should it also hug the left as well? Is the gnd layer supposed to be on one of these 4 layers under the IC? Thanks!

Answer 1

Hi,

Theres couple of issues I see from your image. The antenna needs a matching circuit on the transmission line.

There should be ground plane on the left of the antenna rather than clearance. The button on the left of the antenna might also affect the performance a bit due to proximity.

How long is this PCB may I ask?

Comments

Many thanks for your reply! Understood, I will modify the board to add placements for matching components. Do you have recommended values for SX1276 based modules to start with?

I will add back the ground plane to the left of the antenna, understood. I will keep the button however, as that is a UI requirement. But understood that might cause some attenuation as well.
Below is a full picture of the PCB, measuring 28x50mm. Any additional advice you have to offer is appreciated, thanks again.

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Hi,

You could start with the matching in the datasheet. The ground plane is a bit short for this antenna. Would you be open to other antenna suggestions? but it may require relocation of the button.