TWS Bluetooth earphone antenna
The biggest reason why Bluetooth headphones are so popular is that they are wireless and get rid of the shackles of wired headphone cables. Bluetooth headsets transmit signals through radio waves, so antenna design is very important. This article briefly introduces the common types of antennas used in handheld digital products.
1. PCB antenna.
The PCB antenna is an antenna directly composed of copper foil on the PCB circuit board, which has the advantages of low cost, high batch stability, and no debugging in production. The disadvantage is that it is only suitable for a single frequency band, and because it is composed of PCB copper foil, the antenna position is relatively limited. In addition, the PCB antenna generally requires a large headroom area, and the size of the antenna itself is also large. PCB antennas are widely used in laptops, TV boxes, etc. The PCB antennas in Bluetooth headsets are shown in the following figure:
2. Ceramic antenna.
The ceramic antenna is a miniaturized antenna suitable for Bluetooth devices. It occupies a small space and has good performance. It has a narrow bandwidth and it is difficult to achieve multiple frequency bands. It can effectively improve the integration of the motherboard and reduce the restriction of the antenna on ID.; The design needs to be imported at the beginning of the definition of the board. Ceramic antennas are divided into block ceramic antennas and multilayer ceramic antennas:
Block antenna: The whole ceramic body is sintered at a high temperature and then the metal part of the antenna is printed on the surface of the ceramic block.
Multi-layer antenna: The firing adopts the low-temperature co-firing method to say that the multi-layer ceramics are stacked and aligned and then sintered at high temperature, so the metal conductor of the antenna can be printed on each ceramic dielectric layer according to the design requirements, so that it can effectively Reduce the size of the antenna, and can achieve the purpose of hiding the antenna.
Since the dielectric constant of the ceramic itself is higher than that of the PCB circuit board, the use of a ceramic antenna can effectively reduce the size of the antenna while ensuring the performance of the antenna. The disadvantage of ceramic antennas is that they have consistency problems, they are large, and they are also limited when placed. Ceramic antennas are the most used in IoT products, such as GPS antennas and Bluetooth antennas.
3. LDS antenna.
LDS antenna technology is laser-direct-structuring technology, which uses a computer to control the movement of the laser according to the trajectory of the conductive pattern, and projects the laser onto the molded three-dimensional plastic device. Within a few seconds, The circuit pattern is activated. Its principle is similar to a PCB antenna, the difference is that LDS uses the shape of the antenna to project a laser onto a plastic casing, and electroplating to form a metal antenna within a few seconds. The biggest disadvantage of LDS antenna is the high cost and complicated process. The biggest advantage is that the antenna can be directly placed on the back of the casing so that the clearance area of the antenna is large and the antenna efficiency is high. It is currently widely used in high-end smartphones, smart watches/bands, and Bluetooth headsets.
