Fonte: https://howchoo.com/g/ndy1zte2yjn/how-to-set-up-wifi-on-your-raspberry-pi-without-ethernet
Add your wpa_supplicant.conf file
Create a file in this directory called wpa_supplicant.conf. The file should contain the following details:
For Raspbian Jessie:
network={
ssid="YOUR_NETWORK_NAME"
psk="YOUR_PASSWORD"
key_mgmt=WPA-PSK
}
For Raspbian Stretch and Raspbian Buster:
country=US # Your 2-digit country code
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
network={
ssid="YOUR_NETWORK_NAME"
psk="YOUR_PASSWORD"
key_mgmt=WPA-PSK
}
Connecting to unsecured networks
For wireless networks with no password, use the following:
country=US # Your 2-digit country code
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev # Include this line for Stretch
network={
ssid="YOUR_NETWORK_NAME"
key_mgmt=NONE
}
With this file in place, Raspbian will move it in /etc/wpa_supplicant/ when the system is booted.
The next step is to boot the Pi and test, but while the SD card is still in your computer I'll mention this now. If you're going to try to connect via SSH, you may need to enable it first. The process is similar to this one.