Custom board design

[Victor Nascimento]

Hello,

I was reading about RF design and some articles say that if the transmission line is short enough, you may not consider impedance-control as the effect is not visible. On my design, I have the nRF51422, a BALUN (Johanson) and a chip antenna (Johanson) and they are really really close to each other (almost pad to pad) which makes it impossible to have the 120mil trace width required by common 1.55mm FR-4 boards.

Do you have any opinion about that? I thought of putting pads for an L matching network between the BALUN and the Antenna. Is that worth?

Thanks in advance

[Hung Bui]

@Vitor: You may get away with the parasitics on the short transmission line, but there are other factors may affect the impedance which is the ground plane, PCB material, housing of the device.

If you just want to have a prototype that works you are fine to have just the balun and the chip antenna with OK RF performance. If you want to optimize the performance a PI tuning network is recommended.

Note: we offer free antenna tuning service, you just have to send us your board and housing for tuning.