When it comes to Bluetooth modules, there is one thing I have to mention, and that is the antenna. What is the antenna? An antenna is a component used to transmit or receive electromagnetic waves. The function of the transmitting antenna is to effectively convert the high-frequency current energy of the transmitter into electromagnetic energy in space; while the function of the receiving antenna is just the opposite, so the antenna is essentially an energy converter.
The Bluetooth module can successfully complete short-distance data transmission regardless of the location or direction of use, but a proper Bluetooth antenna design will help achieve better transmission quality. For example, let's compare two common antennas for Bluetooth modules on the market: IPEX interface external antenna and PCB onboard antenna.
The IPEX interface is connected to an external antenna. Its characteristics are: the signal has good directivity, high efficiency, strong anti-interference ability, can be far away from the interference on the motherboard, and does not need to be debugged too much; as a terminal manufacturer, it only needs to connect one external IPEX antenna; of course, there are disadvantages: high cost and troublesome assembly.
The PCB on-board antenna, as a Bluetooth antenna, refers to the part on the PCB for wireless reception and transmission. When transmitting, it converts the high-frequency current of the transmitter into space electromagnetic waves; when receiving, it converts the electromagnetic waves intercepted from space into high-frequency currents and sends them to the receiver. Its characteristics are: less space occupation, low cost, no need of assembling the antenna separately, not likely to get damaged, and easy assembly of the whole machine.