Several antennas that are common in life

The birth of the antenna has a history of more than one hundred years. It has an important significance for the development of human history. If there is no antenna, communication between many devices requires a physical signal line to realize, which is costly and even impractical. It can be said that the antenna seems to be a network that connects the whole world together. So, what common antennas do we have in our lives?

Base station antenna

This antenna you need to use it every day, as long as you use your mobile phone to communicate. Base station antennas are ubiquitous because they form cellular communications. In urban and rural areas, it is generally in the form of signal towers. In cities, they are usually displayed on the upper floors of buildings or beautified into various forms, such as air conditioners and water tanks. Its main function is to receive the signal from the mobile phone and send a signal to the mobile phone to complete the communication between the base station and the mobile phone. In addition, the radiation from the base station antenna is very small, so you don't have to worry about your body being hurt.

Yagi antenna

This kind of antenna is still relatively common before digital TV and Internet TV did not appear. Because at that time many families used this type of antenna to receive TV signals from TV towers, especially in rural areas, such antennas are still widely used, and some local broadcasts are still in use. It is mainly composed of an active vibrator, a passive reflector and a director.

Speed antenna

Xiaobian said that this antenna may be strange to you and has not seen it. But if you drive speeding one day, it is discovered by it and triggers the camera to take photos. Such antennas are used in speed-measuring radar systems, and there are generally intersections and highway monitoring. The Doppler effect of the speed radar, one of which works: when the speed radar transmits a certain frequency signal through the antenna, when the car approaches the radar, the frequency of the signal reflected by the car is higher than the original transmission frequency. When the car is far away from the radar, the frequency of the signal reflected by the car is lower than the original transmission frequency, and then the data is calculated by the algorithm to calculate the speed of the car. In reality it is generally protected with a radome, which is like this on the road:

The inside is a microstrip array antenna composed of a plurality of radiation patches, which is relatively fine, so the protection of the radome is required.

After listening to Xiaobian's introduction to the speed measuring antenna, is there something that I hate? In fact, the most important thing is that the driver himself obeys the traffic regulations, then it is useless.