Question on antenna matching
Posted: Fri Jan 27, 2017 5:52 pm
Hi,
I'd like to connect an external antenna to the ESP32 but am not sure how to implement the impedance matching. Basically, I'd like to know the impedance of the chip's RF pin.
The hardware design guidelines document specifies in section 3.2.4.1, "RF", that the "...characteristic RF impedance must be 50 Ohm", and it also describes a matching network.
Is my understanding correct that the characteristic impedance of the chip is different from 50 Ohms and the matching network is required to match the chip's impedance to 50 Ohms of the antenna? Or is it required to match the impedance of the reference design's PCB antenna to the 50 Ohms input impedance of the chip?
One additional point: I was unable to figure out how the impedance matching network works. To my knowledge, there exist two variations of the PI network, one with the inductor in series and the capacitors as legs, and another one with a capacitor in series and the inductors as legs. But the proposed circuit has an inductor in one leg and a capacitor in the other leg??
Thank you and greetings
Andreas
I'd like to connect an external antenna to the ESP32 but am not sure how to implement the impedance matching. Basically, I'd like to know the impedance of the chip's RF pin.
The hardware design guidelines document specifies in section 3.2.4.1, "RF", that the "...characteristic RF impedance must be 50 Ohm", and it also describes a matching network.
Is my understanding correct that the characteristic impedance of the chip is different from 50 Ohms and the matching network is required to match the chip's impedance to 50 Ohms of the antenna? Or is it required to match the impedance of the reference design's PCB antenna to the 50 Ohms input impedance of the chip?
One additional point: I was unable to figure out how the impedance matching network works. To my knowledge, there exist two variations of the PI network, one with the inductor in series and the capacitors as legs, and another one with a capacitor in series and the inductors as legs. But the proposed circuit has an inductor in one leg and a capacitor in the other leg??
Thank you and greetings
Andreas