antenna

The RF signal power output by the radio transmitter is transmitted to the antenna through the feeder (cable) and radiated by the antenna in the form of electromagnetic waves. After the electromagnetic wave arrives at the receiving location, it is followed by the antenna (only a small fraction of the power is received) and sent to the radio receiver via the feeder. Obviously, an antenna is an important radio device that emits and receives electromagnetic waves. Without an antenna, there is no radio communication.

There are many varieties of antennas for use under different conditions such as different frequencies, different uses, different occasions, and different requirements.

Internal and External Antennas Compared to current mobile phone antennas, there are mainly two kinds of built-in and external antennas. The built-in antenna must be objectively weaker than the external antenna. The erection of the antenna is as far away as possible from the ground and buildings. When the antenna is close to the reference ground, most of the energy will be concentrated between the antenna and the reference ground and cannot be transmitted smoothly. Therefore, the antenna launch requires a space that is “as open as possible”. . The circuit version of the mobile phone is the reference for the mobile phone antenna. Keeping the antenna away from other circuits of the mobile phone is the key to improving the efficiency of the mobile phone antenna.

However, due to the limitations of the actual environment and the pursuit of convenience for people to carry, the design of mobile phones must be compromised on the electrical side. In fact, the gains of all GSM mobile phone receiving and sending circuits are automatically adjusted according to environmental changes and can be compensated automatically by reasonable parameter settings. Therefore, as far as the mobile phone is concerned, the inner antenna and the outer antenna cannot see the difference when the signal is good.

The difference is that, in the weak signal condition, the signal dead point threshold of the outer antenna, especially the long antenna, will be higher than the inner antenna, that is, in theory, the inner antenna mobile phone can easily lose the signal in the weak signal environment.

For radiation problems, the reduction of antenna efficiency must be compensated with a large transmit power, and under the same conditions, the radiation of the internal antenna will be larger than that of the external antenna. However, the radiation actually received by the human body is related to the structure of the whole machine. The internal antenna mobile phone can also arrange the antenna position reasonably to offset the influence of radiation on the human body.

Radiation The radiation of the mobile phone is mainly caused by the antenna's transmitting module of the mobile phone. The antenna of the mobile phone is very thick, and its role is to reduce the resistance of the launch.

It can be said that the mobile phone antenna is the radiation source of the mobile phone, and it is also impossible to attach the so-called magnetic shield to the earphone because it will change the magnetic field around the antenna and cause the signal of the antenna to change, making the call not work properly.