Description:
The GT-38 wireless serial communication module is a new generation of multi-channel embedded wireless data transmission module. There are a PCB antenna holder ANT1 and a spring antenna welding hole ANT2 on the module, you can select one of the antennas according to your requirement.
Four modes FU1, FU2, FU3, and FU4 have an average operating current of 3.6mA, 80μA, 16mA, and 16mA in idle state, and the maximum operating current is 100mA (full power emission state).
At the transparent transmission mode, baud rate, and wireless communication channel must be set to the same. The factory default settings are FU3, 9600bps (8-bit data, no parity, 1 stop bit), and CH100 (443MHz).  This mode can automatically adjust the air baud rate according to the serial port baud rate, and the communication distance is the farthest at low baud rate.When using, it is generally not limited to the number of bytes sent continuously to the serial port of the module. However, in view of environmental interference and other factors, when a large amount of data is continuously transmitted at a time, some bytes may be lost. Therefore, the host computer should have mechanisms such as answering and resending to avoid information loss. 

Characteristics:
Power supply voltage : 3.2 V -- 5.5 V (if the modules working long hours in emission state, suggested that when the power supply voltage is greater than 4.5 V, you need concatenating a 1N4007 diode to avoid module built-in LDO got fever)
Long-distance wireless transmission (opening 1200 m / FU4 mode, air baud rate 1000bps)
Operating frequency range (433-458.5MHz, up to 255 communication channels)
Maximum 100mW (20dBm) transmit power (8-speed power can be set)
Four working modes to suit different applications
Built-in MCU for communication via serial port and external devices
The number of bytes sent at one time is up to 256 bytes.
Module supports one-to-one, one-to-many, many-to-many connections, transferring data to each other in a half-duplex manner. 

Spring antenna:
Frequency Range(MHz)：433MHz+/-10MHz
V.S.W.R：<=1.5
Input Impedance( OHM)：50
Gain(dBi)：4dBi
Diameter(mm)：5.5
Length(mm)：38.5MM

PCB Antenna ( with adhesive):
Frequency range: 400~470 MHz
Gain: 2.5dBi
Standing wave ratio: S.W.R <1.5
Impedance: 50 ohm
Antenna size: 61*7.5mm
Connector type: IPEX connector / welding head two optional
Wire: 1.13 line
Line length: 15cm 

Packing List:

1 * 433Mhz SI4463 Wireless Module Serial Port 1200M
1 * Spring antenna
1 * PCB Antenna