If the ground circuit of the RF circuit is not handled properly, some strange phenomena may arise. For digital circuit design, even if there is no ground layer, most of the digital circuits perform well. In the RF band, even a very short ground wire acts like an inductor. Roughly calculated, the inductance per millimeter length is about 1nH, and the inductance of the 10mmPCB line is about 27 433MHz. If the ground layer is not used, most of the ground wire will be longer and the circuit will have no design characteristics.