What Should I Consider When Buying a Cell Phone Antenna?

Mobile phone antenna, that is, the device used to receive signals on mobile phones. Older mobile phones have convex antennas, and most new mobile phones have been hidden in the fuselage. These antennas are mainly inside the mobile phone, and the inside of the mobile phone cannot see the contents.

Mobile phone antenna

Mobile phone antenna, that is, the device used to receive signals on mobile phones. Older mobile phones have convex antennas, and most new mobile phones have been hidden in the fuselage. These antennas are mainly inside the mobile phone, and the inside of the mobile phone cannot see the contents.

The mobile phone antenna is a standing wave antenna. The impedance mismatch of the antenna will cause a large number of signal reflections and reduce the radiation efficiency of the antenna. At the same time, the gain of the antenna in a wide frequency band will be jittered due to the effect of reflection. For 6, the breakdown voltage of the front end of the mobile phone will be reduced to 1/6, and the power capacity will be reduced. The influence of standing wave of mobile phone antenna on antenna efficiency must not be careless. The standing wave requirements of the antenna are currently less than three.

Chinese name

Mobile phone antenna

Foreign name

Mobile antenna

Use

receive signal

Receiving principle

radio

Radiation

Unstable

Types of

Bracket type, attach type, etc.

Antenna input impedance

The input impedance of the antenna is the impedance value obtained by looking into the antenna end at the interface between the transceiver and the antenna. This value has a great influence on the radiation efficiency of the antenna, the in-band gain fluctuation of the antenna, and the power capacity of the antenna front end.

Working frequency and working bandwidth

The bandwidth of an antenna refers to the frequency band range that meets all the antenna's specifications. Operating frequencies are all frequencies within the antenna's bandwidth. The working bandwidth is defined by multiple indicators, so the bandwidth with the narrowest bandwidth needs to be taken. In mobile phone antennas, the bandwidth limited by directional pattern bandwidth, polarization bandwidth and other factors is greater than the impedance bandwidth. The bandwidth of the standing wave is used as the working bandwidth of the antenna.

Beam pattern

The antenna beam pattern is used to describe the correlation between the energy radiated by the antenna and any position in space. The relative intensity or absolute intensity of the electromagnetic wave radiated by the antenna at each position in the space can be obtained from the pattern. . There is no doubt that the horizontal pattern of the mobile phone antenna is required to be omnidirectional. In fact, the beam pattern of the mobile phone antenna is not important, mainly during the use of the mobile phone. At this time, the radiation characteristics of the mobile phone antenna and the radiation characteristics of the single antenna Is not the same. The mobile phone antenna pattern only requires that the horizontal plane be approximately omnidirectional.

Directivity and antenna gain

The directivity of an antenna is related to its beam pattern, so the directivity is also a function of the azimuth. It is defined as follows: D (, ) = [radiation intensity of the antenna in the direction of (, )] / [omnidirectional antenna Radiation Intensity] In practical applications, since the radiation efficiency of the antenna itself must be considered, the size of the antenna gain is usually used instead of the directivity. The relationship between the two is:

G (, ) = eD (, )

Among them, the radiation efficiency of the antenna is related to the amount of energy lost during the electromagnetic wave radiation process.

All possible energy losses of the antenna in the process of energy transmission and reception include: energy reflection caused by impedance mismatch at the input end of the antenna, energy loss caused by the material of the antenna at high frequencies, and energy consumed in the propagation medium. energy. The gain of the mobile phone antenna does not represent the efficiency problem when the mobile phone is used: the index that really represents the antenna gain characteristics should be the average effective gain of the antenna, which is related to the use environment, the use method, the structure of the mobile phone, and the design of the mobile phone.

At present, mobile phone antennas are mainly built-in and external antennas. The built-in antenna must be objectively weaker than the external antenna. The installation of the antenna is as far away from the ground and buildings as possible. When the antenna is close to the reference ground, most of the energy will be concentrated between the antenna and the reference ground, and it will not be able to transmit smoothly. . The mobile phone circuit board is the reference ground of the mobile phone antenna. Keeping the antenna away from other mobile phone circuits is the key to improving the transmission efficiency of the mobile phone antenna.

However, due to the limitations of the actual environment and the requirements of everyone's pursuit of portability, the design of the mobile phone must be compromised on the electrical side. In fact, the gain of the receiving and transmitting circuits of all GSM mobile phones can be automatically adjusted according to environmental changes, and the relevant losses can be automatically compensated through reasonable parameter settings. Therefore, as far as the whole mobile phone is concerned, the difference between the inner antenna and the outer antenna cannot be seen when the signal is relatively good.

There are some differences. In the case of a weak signal, the threshold of the dead point of the external antenna, especially the long antenna, will be higher than that of the internal antenna. In theory, the mobile phone with the internal antenna is more likely to lose signals in a weak signal environment.

There are many external antennas for mobile phones. We probably know the manufacturing process and materials. For mobile phones with built-in antenna. FPC is a flexible circuit board. The built-in antenna of the mobile phone is designed and manufactured using FPC. It is affixed to the inside of the mobile phone case and is connected to other parts with a bracket and a thimble.

For radiation problems, the decrease in antenna efficiency must be compensated with large transmission power. Under the same conditions, the radiation of the inner antenna will be greater than that of the outer antenna. However, the actual human body's radiation is related to the structure of the whole machine. The internal antenna mobile phone can also properly arrange the antenna position to offset the impact of radiation on the human body.

Radiation problem

The radiation of the mobile phone is mainly brought by the antenna transmitting module of the mobile phone. The antenna of the mobile phone is very large. Its role is to reduce the resistance of the transmission.

It can be said that the mobile phone antenna is a mobile phone

PIFA Pifa antenna

2. Several types of PIFA antenna

Any appliance has radiation, such as a refrigerator, TV, fan, computer, etc. at home. These all have radiation, but the amount of radiation varies.

The amount of mobile phone radiation depends on the mobile phone. Some mobile phones have a large amount of radiation, and some have a small amount of radiation.

In order to avoid too much harm to the body, do not place your phone too close to your brain when sleeping, especially under the pillow. Pay attention to the usual phone calls, preferably not more than an hour. Do not put your mobile phone in your pocket near your heart in your daily life.

Radiation is definitely there, and it is good for the body to pay attention to it.