Many customers have encountered this situation, an antenna product, the nominal operating frequency, gain, bandwidth, standing wave and other electrical indicators are very good. However, after using their own products, the communication quality is very poor, and even can not be used, in some high-power occasions will burn out the product. So I thought I bought fakes. There are also some customers who directly refer to the competitor's product design, so they copy it directly. After the results were copied to their own products, the antenna effect became very poor and it was not clear what the problem was. Today we will talk about the main reasons for this situation.
The antenna function is to convert the RF circuit signal and the wireless electromagnetic wave signal to each other. Since the characteristics of electromagnetic waves during propagation are greatly affected by the surrounding environment, the characteristics of the antenna are also seriously affected by the surrounding environment.
As shown in the figure, a wirelessly controlled water valve product, the customer chose a standard spring 433MHz antenna, but the performance in the environment has become very poor, the communication distance is more than ten meters, almost impossible to use.
As the above example, the standard spring antenna selected by the customer is used inside the product. The frequency is more than 100 MHz to the high frequency. It is almost impossible to use at 433 MHz, and the energy cannot be effectively converted to space radiation. Finally, we chose a custom FPC antenna based on the product structure and internal component layout
Factors affecting the performance of the antenna in the surrounding environment:
With the same antenna, the performance of the antenna is completely different when the surrounding environment is different. The surrounding environment here mainly includes whether there is a metal conductor around the antenna and whether there is an insulator material around the antenna.
The effect of the insulator:
The presence of an insulator around the antenna also has an effect on the performance of the antenna. This is because the insulator is not electrically conductive, but the dielectric constant of the insulator is completely different from the dielectric constant in air. Therefore, there is no insulator around the antenna, or there are insulators of different materials, and the performance of the antenna will change.
More common factors include the plastic housing outside the antenna, the thickness of the circuit board at the bottom of the onboard antenna, the thickness of the plastic case, the distance from the antenna, and the external conditions such as the wall or wooden door installed, which will affect the antenna performance. In this case, the antenna should also be professionally designed and debugged. Otherwise, the performance of the antenna will cause the antenna performance to be degraded or even unusable.
Product housing impact on antenna performance
空气中：In the air
塑料壳内： Inside the plastic case
Metal conductor effect
The presence of metal conductors around the antenna is the most influential factor in antenna performance. Because the metal conductor is shielded from the electromagnetic wave signal, and the metal is too close to the antenna, it affects the charge distribution of the antenna, which causes the RF signal on the antenna to be directly coupled to the metal and cannot be converted into electromagnetic waves, which will seriously affect the performance and indicators of the antenna.
For example, there are circuit boards around the antenna, and the grounding and routing on the circuit board are all conductors, which will change the antenna's specifications. Please note that the different parts of the circuit of the PCB onboard antenna also affect the antenna performance and the antenna cannot be shared. Similar metal parts, metal casings, conductors or semiconductor materials around the antenna of your product can seriously affect the antenna effect. Therefore, when there is metal around your antenna that cannot be avoided, the antenna must be professionally designed, and the performance directly purchased in the market will be seriously degraded or even impossible to use.
Impact of product housing on antenna performance (battery, motor and board)
塑料壳内：Inside the plastic case
周围加金属器：Add metalwork around
Of course, when there are no metal conductors and insulators around the antenna, it is ok to directly purchase antennas with good performance indicators on the market. However, if there are any factors affecting the performance of the antenna mentioned above, especially the built-in antenna and PCB microstrip antenna, it must not be used directly, and must be customized for its own products.
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