First, the principle of antenna
1.1 Antenna definition:
Ø Effectively radiate electromagnetic waves in a particular direction in a particular direction, or a device that can effectively receive electromagnetic waves in a particular direction of space.
1.2 Antenna function:
Ø Energy conversion - conversion of guided wave and free space waves;
Ø Directed radiation (reception) - has certain directionality.
1.3 Antenna radiation principle
1.4 antenna parameters
U radiation parameters
Ø Half power beam width, front and rear ratio;
Ø polarization method, cross polarization identification;
Ø Directional coefficient, antenna gain;
Ø The main lobe, the pair of petals, the sidepag inhibition, the zero padding, the beam under the beam ...
U circuit parameters
Ø Voltage station wave ratio VSWR, reflection coefficient γ, echo loss RL;
Ø Enter the impedance ZIN, transport loss TL;
Ø Isolation ISO;
Ø Passive third-order intermodulation PIM3 ...
U antenna sidepag
u Horizontal beam width
U before and after: Specifies the ratio of radiation power and rear ± 30 ° in the antenna
U gain and antenna size and beam width relationship
The "tire" is flattened, the higher the signal, the higher the gain, the larger the antenna size, the narrower the beam width;
Ussence points for Usten gain:
Ø The antenna is passive device and cannot generate energy.
The antenna gain is just the ability to effectively concentrate radiation or receiving electromagnetic waves in a particular direction.
Ø The gain of the antenna is produced by the vibrator.
The higher the gain, the longer the length of the antenna.
Gain increased by 3dB, and the volume is doubled.
Ø The higher the antenna gain, the better the direction, the more energy is, the narrower the wave petals.
1.5 radiation parameters
U polarization: refers to the state of the electric field vector in the spatial movement.
1.6 circuit parameters
u Roll loss
In this case, the return loss is 10 Log (10 / 0.5) = 13dB
VSWR (standing wave ratio) is another metric method for this phenomenon
u I I I I I I I Zegemic: It is a ratio of another polarization signal received by a polarization.
u Passive Travel (PIM):
When the two frequencies f1 and F2 are input to an antenna, with other frequencies, such as 2F1-F2 and 2F2-F1 (3th order), such as 2F1-F2 and 2F2-F1 (3th order), and the like due to the nonlinear effect, the signal division frequencies F1 and F2 of the antenna radiation.
Second, antenna products
2.1 antenna naming method
Antenna category:
ODP (Outdoor Directional Plate Antenna), OOA (Outdoor Top Antenna), OCS (Outdoor Bidirectional Antenna), OCA (Outdoor Bunch Antenna), OYI (Outdoor Eight Wooden Antenna), OR (Outdoor Throwing Netty lines), IWH (indoor wall hanging antenna), etc.
Half power angle:
032, 065, 090, 105, 360 (base station antenna)
020, 030, 040, 050, 060, 075, 090, 120, 160, 360 (straight discharge antenna)
Polarization mode:
R (bipolarization), V (single-polarized)
Gain:
According to the actual indicator, the current maximum is 21dBI
Connector Type:
D (DIN head), N (n-type head), S (SMA head), T (TNC head), etc.
Frequency band:
Specifications: Roman alphabets represent the second generation of products. The back letters and numbers represent information such as tilting angle, excipient, electric tones .f assault; V electrical tone; RV remote electric ton
2.2 base station antenna
All-toch antenna
Dual-frequency antenna
Three-frequency antenna
2.3 Distribution System Antenna
Smoke sensing type ceiling antenna
Lamp type ceiling antenna
Wall-hanging antenna
2.4 Outdoor Antenna
Dungent antenna: Ø narrow beam, directional intensity Ø high before and after
Eight wooden antenna
Corner reflection antenna
Parabolic antenna
User antenna
Third, passive device overview
3.1 Overview of Microwave Passive Devices
Ø Passive device is divided into linear devices and nonlinear devices.
Ø Line-shaped passive device has a mutually transmit and non-interiors.
Ø Linear mutual easier components only perform linear transformation of microwave signals without changing frequency characteristics, and meets the principle of mutual transmit.
Usually, the passive device we say is all linear mutual components.
3.2 Linear mutual easy components tree map
3.3 power
Ø The power is a device that divides all the output signal energy into two or multiplexed outputs.
Essentially an impedance converter.
Ø Can you use the power to replace the across the crossover?
Ø When using the synthesizer, it is not only required to high isolation, the low wave ratio, but also support high power.
Considering that the commonly used cavity power saver output port does not match, the large standing wave; the microstrip power is contrary to low power, and we do not recommend the use of a power inverse to replace the crossover.
3.4 Classification of Power Software
3.5 Software classification comparison
3.6 Chamber Power Structure Characteristics
Ø Coronida power, high-quality alloy as a conductor, filler medium is air;
Ø Can withstand a relatively large power, up to 200W; medium loss, conductor loss is basically negligible, the insertion loss is small, can do 0.1 dB or less.
Ø However, since there is no isolation resistance, the output port isolation is small, so the cavity power unit cannot be used as a power synthesizer.
3.7 Schematic diagram of the scorer test indicator
As shown in the figure, 1 mouth can measure the standing wave ratio; 2, 3 can be measured insertion loss, and due to the characteristics of the cavity power unit itself, the isolation of the output port standing wave and the output port is not proposed. .
Fourth, the coupler introduction
4.1 coupler
Ø coupler is a part of the energy of the input signal through an electric field, and the magnetic field coupling is partially output, and the remainder is an output of the output to complete the power allocated.
Ø The power distribution of the coupler is not aliquoted.
A power sampler is also known.
4.2 Description of the principle of four-port network coupler
4.3 Coupler Classification
4.4 Directional Coupler
Ø Directional coupler is common to sample the slight wave signal to the microwave signal, mainly to separate and isolate signals, or mix different signals, when there is no inner load, directional coupling is often a four-port network.
Ø Directional coupler often achieves two methods
4.5 cavity coupler
Features: Bearing high power, showing low loss.
reason:
1. The internal filling medium in the cavity is air. During the transmission process, the medium dissipation due to the cause of the air medium is much lower.
2. Its coupling wire belt is generally made of conductive conductors such as copper surfaces, and conductor losses are basically negligible.
3. The cavity is large and cool. With high power.
4.6 Coupler Indicator Test Schematic
As shown, in which the directionality = the isolation-coupling degree, the data cannot be read.
Five, 3DB bridge introduction
5.13DB bridge
The 3DB bridge coupler is one of a directional coupler.
As the power synthesizer is used, the two input signals are interposed ports, while the coupled output and direct output port are mutually easy. As two outputs, the loss is not considered, the sum of the input signal power is divided into two output ports.
When it is used as a single-port output, the other output must connect to match the power load to absorb the output power of the port, otherwise it will seriously affect the system transfer characteristics, which simultaneously brings additional 3dB loss, which System application, there is an impact on the cost and reliability of its active part.
5.2 Main Engineering Application
Mainly applied to the assembly application between different carriers in the same frequency band.
Due to the discrete of the circuit and processing assembly, the isolation of the electrical bridge coupler input port is relatively low, and it is not recommended to apply the assembly application between different frequency bands.
In summary, in the application of the four-frequency, in addition to the 3DB bridge in the same frequency band, such as the receipt of the GSM downstream frequency band), only the 3DB bridge can only be used without applicable duplex / multi-worker It is recommended to use a duplex / multi-worker in use to improve the performance indicators of the system to increase reliability.
5.3 Software VS coupler
6. Introduction to the crossover
6.1
Ø Role:
Synthesize multiple signal outputs
Ø Category:
Classified according to the actual combined frequency band
6.2 Complex VS Bridge VS Power Software
Seven, attenuator introduction
7.1 Attenuator
Ø Attenuator is a two-port mutual component
Ø The most commonly used absorbent attenuator is the absorbed attenuator.
Ø It is usually used in the project to consist of the coaxial attenuator, consisting of "π" or "T" type attenuation network.
Ø Coaxial attenuator usually has two types of fixation and variable attenuation.
Ø Attenuator is mainly used to detect the dynamic range of the microwave signal transmission energy in the system, consume excess energy, thus extended signal measurements, such as power meter, spectrum analyzer, amplifier, receiver, and the like.
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