Do you know if you choose to use the antenna correctly? ? Come up and get up! !

In this wireless era, we are receiving or sending signals everywhere. Whether it is a cell phone, a notebook, a computer, or almost all wireless products, an antenna is used. Then do you know or understand some basic classifications and options for receiving or sending antennas? ?

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Here's what I used to popularize the antenna's common sense:

First, the working principle of the antenna The basic function of the antenna is to radiate and receive radio waves.

When transmitting, the high-frequency current is converted into electromagnetic waves; when receiving, the electric wave is converted into high-frequency current.

According to the electromagnetic field theory, when a conductor passes a high-frequency current, electric and magnetic fields are generated in the surrounding space. When the length of the conductor is large enough (comparable with the wavelength), electromagnetic waves can be effectively radiated;

After electromagnetic waves radiate from the transmitting antenna, they propagate out on all four sides to form an electromagnetic field.

A wire is placed in the alternating electromagnetic field, and under the action of electromagnetic waves, the wire generates an induced electromotive force.

The wire is connected to the receiving device and a high-frequency current is generated at the input of the receiving device.

Second, the reciprocity principle of the antenna The transmitting antenna and the receiving antenna belong to the energy converter and have "reversibility";

The parameters used when the antenna is used for transmitting and the parameters when receiving remain unchanged. This is the reciprocity principle of the antenna.

Third, the antenna parameters discussed in the mobile communication performance of the antenna is mainly concerned about its signal coverage and radiation intensity.

The factors that determine the performance of the antenna are somewhat independent of the antenna itself, such as the height of the antenna.

Some factors are related to the design and production process of the antenna. These factors are called antenna parameters.

IV. Main Antenna Parameter Pattern Efficiency Gain Input Impedance Operating Band Polarization Mode 5. Direction of Antenna 5.1. The antenna has different radiation or receiving capabilities for different directions in space. This is the antenna's directionality.

5.2. In the horizontal plane, the antenna that radiates and receives no maximum direction is called an omni-directional antenna, and the antenna that has one or more maximum directions is called a directional antenna.

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6. The antenna pattern is used to indicate the correspondence of the radiation or receiving intensity of the antenna with the spatial direction.

7. Omnidirectional Antennas Omnidirectional antennas are commonly used in point-to-multipoint communication centers due to their lack of directionality.

VIII. Directional Antennas Directional antennas have the largest radiation or reception direction, so the energy is concentrated and the gain is relatively high, which is suitable for long-distance point-to-point communication.

9. The lobe where the maximum radiated power of the lobe width antenna pattern is located is called the main lobe, and the remaining are the side lobes;

On both sides of the maximum radiation direction of the main lobe, the angle between two points where the radiation intensity is reduced by 3 dB is defined as the lobe width.

10. The horizontal lobe width of the horizontal lobe omnidirectional antenna is 360 degrees eleven, and the vertical lobe width of the vertical lobe base station directional antenna is about 10 degrees;

For the same type of antenna, when the gain is the same, the wider the horizontal lobe, the narrower the vertical lobe;

A narrow vertical lobe generates a signal "dead zone" near the base station.

12. Antenna tilt adjustment signal is limited to the "dead zone" in the area served by the antenna and reduce the interference to other cells.

Mechanical tilt: less than 10 degrees ESC down: the angle is adjustable, the back flap is tilted down at the same time. The antenna efficiency is defined as the ratio of the antenna radiation power Pr to the antenna input power Pin;

The sum of the antenna radiated power and the consumed power Ps is the input power.

14. Antenna Gain Antenna gain coefficient is the product of the directional coefficient and the antenna efficiency. The narrower the main lobe of the pattern is, the smaller the side lobe is, and the higher the gain is.

Under the same conditions, the higher the antenna gain, the farther the radio wave travels, the higher-gain antenna is generally used for the base station antenna.

15. Antenna input impedance The input impedance of the antenna is the ratio of the input voltage to the input current.

In order for the antenna to obtain maximum power, the input impedance of the antenna should be matched with the characteristic impedance of the feed line.

16. When the various electrical performance parameters of the working frequency band antenna do not exceed the allowable range, the corresponding working frequency width is the antenna operating frequency band.

For a frequency-division-duplex transceiver antenna, the operating bandwidth of the antenna must be considered.

17. Antenna polarization is divided into linear polarized antennas, circular polarized antennas and elliptical polarized antennas;

The base station uses linear polarization, and is divided into vertical polarization and horizontal polarization.

18. The type of antenna is divided according to the working frequency band: short-wave, ultra-short wave, microwave according to the purpose: base station, mobile station according to the direction of sex: omnidirectional, orientation by structure points: linear, surface, antenna array 19, commonly used Short wave antenna whip antenna (top loading)

Double loop antenna Three loop antenna oblique antenna dipole antenna, clavial antenna diamond antenna traveling wave antenna twenty, base station commonly used antenna base fixed communication equipment antenna, there are two kinds of omnidirectional antenna and directional antenna;

Due to the requirements of communication range, base fixed antennas are generally elevated.

Twenty-one, high-gain omni-directional antenna half-wave dipole antenna: The half-wave oscillator is vertically arranged, and the horizontal direction diagram is unchanged, and the vertical direction will be enhanced; it can be two units, four units or six units.

Upright Whip Antenna Coaxial Dipole Antenna Brown Antenna

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22. Directional antennas are used for sector-shaped signal coverage, also known as sector antennas in mobile communications;

Antenna gain is higher, which helps to control the antenna coverage and reduce the impact on the neighboring cells.

Angle reflection antenna Plate antenna Lead antenna (Yagi antenna)