During the construction of outdoor long-distance wireless transmission, we usually require the customer to ensure that there is no obstruction between the two end devices and that the two parties can see each other clearly. After the customer hears this requirement, they generally believe that as long as it is theoretically visible, the requirement can be met. In a short-distance transmission environment, this situation can be regarded as meeting the transmission requirements. However, in long-distance wireless transmission, in addition to having no obstruction between the two end devices, the following requirements must also be met.

       Usually, when setting up a long-distance wireless transmission device, in order to achieve a good transmission effect, we generally need to avoid the influence of three situations:

       1. The curvature of the Earth's surface: As is well known, the Earth is round. Although we see a flat surface, when the distance is far, even though both are surfaces of the Earth, they are still not visible to each other. As shown in the following picture:

      II. Actual Obstacles: This is something we can easily understand. During the transmission of wireless devices, if there are obstacles between two points, from one end of the device to the other, the straight line is blocked. This situation will have an impact on the effect of wireless transmission.

      III. The blocking effect of the Fresnel zone. This situation is one that we don't fully understand. The detailed explanation of the Fresnel zone has been provided in other technical articles. Here, we will only give a brief description. It refers to the spindle-shaped space for data transmission between two wireless devices, as shown in the following figure:

       Now, let's conduct a detailed analysis based on a real-life scene of long-distance outdoor transmission, as shown in the following picture:

 Figure 1

Figure 2

       From the two on-site diagrams above, we can see that the transmission distances at both ends are approximately 20 kilometers. However, based on our previous understanding of wireless transmission obstructions, it can be observed that the transmission effect in Diagram 1 is better. This is because among the three factors affecting wireless transmission, Diagram 1 was almost unaffected. Looking at Diagram 2, although there was no obstruction during the transmission process and it was unobstructed in terms of visibility, its Fresnel zone was significantly affected. Therefore, although there were no communication issues during the transmission process, the actual transmission bandwidth was not as good as the on-site effect in Diagram 1.

       Of course, the factors influencing wireless transmission are not limited to the above three. There are also the local electromagnetic environment, weather, humidity, etc. If users have actual needs for wireless transmission, they can contact the professional technicians of Shenfang Technology to provide them with professional technical service support.