Antenna Classification and how to select

Mobile communications antenna technology developed rapidly, initially China mainly use the ordinary directional and omni-directional mobile antenna, and later the widespread use of mechanical antenna, and now some provinces and cities have begun to use the mobile network antenna and dual polarized mobile antenna. Because the frequency, gain and front-to-back ratio of the various antennas used in the mobile communication system are not very different, they meet the requirements of the network index. We will focus on the change of the antenna pattern and the wireless network from the angle of the mobile antenna In this regard, the above-mentioned several antennas are analyzed and compared.

Omnidirectional antenna, that is, in the horizontal pattern shows 360 ° are uniform radiation, that is, usually said non-directional, in the vertical pattern shows a certain width of the beam, in general, the smaller the lobe width, The greater the gain. Omnidirectional antenna in the mobile communication system in general application and suburban county system of the station type, covering a large area.
Directional antenna, in the horizontal direction of the performance of a certain range of radiation, that is, usually has a directional, in the vertical pattern shows a certain width of the beam, with the omni-directional antenna, the smaller the lobe width , The greater the gain. Directional antenna in the mobile communication system is generally used in the urban community system of the station type, covering a small, user density, high frequency utilization.

According to the requirements of the establishment of different types of base stations, and different types of base stations can be selected according to different types of antennas. Selection is based on the above technical parameters. For example, the omnidirectional station is used in the horizontal direction of the gain is basically the same omnidirectional antenna, and the directional station is the use of the horizontal direction of the directional changes have obvious directional antenna. Generally, an antenna with a horizontal beam width B of 65 ° is selected in the urban area, and an antenna with a horizontal beam width B of 65 °, 90 ° or 120 ° can be selected in the suburbs (depending on the station configuration and the local geographical environment) It is most economical to choose an omni-directional antenna that can achieve a wide range of coverage.
Mechanical antenna

The so-called mechanical antenna, refers to the use of mechanical adjustment of the tilt angle of the mobile antenna. After the mechanical antenna is installed vertically with the ground, it is necessary to adjust the inclination of the antenna by adjusting the position of the antenna on the back of the antenna due to the requirement of network optimization. In the adjustment process, although the distance between the main lobe direction of the antenna is significantly changed, the amplitude of the vertical and horizontal components of the antenna is constant, so the antenna pattern is easily deformed. It is proved that the optimum inclination angle of the mechanical antenna is 1 ° -5 °. When the angle of inclination is 5 ° -10 °, the antenna pattern is slightly deformed but does not change greatly. When the inclination angle is 10 ° -15 When the mechanical antenna is tilted by 15 °, the shape of the antenna pattern changes greatly, and the pear shape when there is no tilting is changed into a spindle shape. At this time, although the main lobe direction The coverage distance is obviously shortened, but the entire antenna pattern is not within the base station sector, and the signal of the base station is received within the adjacent base station sector, resulting in severe intra-system interference. In addition, in the daily maintenance, if you want to adjust the mechanical antenna down angle, the entire system to shut down, can not adjust the antenna tilt at the same time to monitor; mechanical antenna adjustment antenna tilt angle is very troublesome, generally need to maintain personnel to climb to the antenna The adjustment angle of the mechanical antenna is the theoretical value calculated by the computer simulation analysis software, and there is some deviation from the actual optimum down angle. The adjustment angle of the mechanical antenna is 1 °, the third-order intermodulation index For -120dBc.

Adjustable antenna
The so-called antenna, refers to the use of electronic adjustment down angle of the mobile antenna. The principle of electronic dip is to change the phase of the co-linear array antenna, change the magnitude of the vertical component and the horizontal component, change the strength of the synthetic component field strength, so that the vertical direction of the antenna diagram down. Due to the increase and decrease of the field strength in each direction of the sky line, it is guaranteed that the antenna pattern does not change greatly after changing the inclination angle, so that the distance of the main lobe direction is shortened, and the whole direction map is reduced in the service area Small coverage area but no interference. It has been proved that the antenna pattern is approximately the same as that of the mechanical antenna when the inclination angle of the ESC is changed at 1 ° -5 °. When the inclination angle changes at 5 ° -10 °, the antenna pattern is larger than that of the mechanical antenna The antenna pattern is larger than that of the mechanical antenna when the inclination angle is 10 ° -15 °. When the mechanical antenna is tilted by 15 °, the antenna pattern is obviously different from that of the mechanical antenna. The direction of the antenna pattern changes little, the main lobe direction to cover the distance significantly shortened, the entire antenna pattern in the base station sector, increase the down angle, you can make the sector coverage area is reduced, but does not produce interference, such a party Figure is what we need, so the use of electric antenna can reduce the call to reduce interference. In addition, the ESC antenna allows the system to adjust the vertical direction diagram under the condition of non-stop, real-time monitoring of the adjustment effect, adjust the inclination of the step precision is also higher (0.1 °), so the network can be fine Adjustment; the third-order intermodulation index of the ESC is -150dBc, which is 30dBc worse than the mechanical antenna, which is helpful to eliminate the adjacent frequency interference and spurious interference.
Dual polarized antenna
Dual polarized antenna is a new type of antenna technology, combined with + 45 ° and -45 ° polarization direction of the antenna orthogonal to each other and work in the transceiver duplex mode, so its most prominent advantage is to save a single orientation Base station antenna number; general GSM digital mobile communication network directional base station (three sectors) to use nine antennas, each fan using three antennas (space diversity, two hairs), if the use of dual polarized antenna, each Only one antenna is required for the sector. At the same time, the polarization of ± 45 ° can ensure that the isolation between + 45 ° and -45 ° is satisfied between the two antennas. (≥30dB), so the space between the dual-polarized antenna spacing only 20-30cm; In addition, the dual-polarized antenna with the advantages of the antenna, in the mobile communication network using dual-polarized antenna with the ESC Antenna, can reduce the call loss, reduce interference, improve the quality of service across the network. If the use of dual-polarized antenna, due to dual-polarized antenna on the erection of the installation requirements are not high, do not need to build the tower, only need to frame a 20cm diameter iron column, the dual polarization antenna fixed in the corresponding direction fixed on the iron You can save infrastructure investment, while making the base station layout more reasonable, the base station site selection easier.

For the choice of the antenna, we should be based on their mobile network coverage, traffic, interference and network quality of service and other practical conditions, select the mobile network for the needs of the mobile antenna: in the base station intensive high traffic area, should try to use Dual polarized antenna and electric antenna; in the edge, the suburbs and other traffic is not high, the base station is not intensive areas and only require coverage of the region, you can use the traditional mechanical antenna. China’s current mobile communication network in the high traffic density area of the call loss is higher, more interference, one of the important reasons is the mechanical antenna down angle is too large, the antenna down angle is too large, the antenna pattern is seriously deformed. To solve the high capacity of the high traffic area, you must shorten the station distance, increase the antenna down angle, but the use of mechanical antenna, down angle greater than 5 °, the antenna pattern began to deform, more than 10 °, the antenna pattern Serious deformation, so the use of mechanical antenna, it is difficult to solve the user high density area call loss is high, interference problems. Therefore, it is recommended to use the antenna or dual polarized antenna in the high traffic density area to replace the mechanical antenna. The replacement mechanical antenna can be installed in areas such as rural areas and suburbs with low traffic density.

What is DAB?

DAB is (DigitalAudioBroadcasting) shorthand, it offers near CD-quality sound, broadcast and business opportunities of additional data service, the listener can more easily listen to completely interference-free broadcast industry to lower launch costs to provide CD-quality programs to audience, will lead the receiver and transmitter industry opportunities, but also to promote the broadcasting sky towards multimedia broadcasting (DMB) in the world.

DAB is the second AM, FM broadcasting traditional analog broadcast the third generation – the digital broadcast signal, its appearance is a revolution in broadcasting technology. Digital broadcasting is immune to noise, interference, anti-wave propagation fading, the advantages for high-speed mobile reception, and so on. It provides CD-quality stereo sound quality, signal distortion is almost zero, can reach “crystal clear” enthusiast broadcast sound quality, especially for broadcast “classical music”, “Symphony”, “Pop”, etc., being extremely professional musicians, music enthusiasts and audiophiles sought after! But within the range of from multipath interference, in order to ensure that fixed, portable and mobile reception of high quality.

Sensual simultaneously “listening” technology

According to the popular saying, DAB is a product of the era of the migration to digital audio transmission arising from the analog era, it also came after AM and FM broadcasting system of the third generation. But even more interesting is that, relying on DAB, in theory, you can use the eye to “listen” to the broadcast – Because digital features, DAB can transmit any text or even an image signal. So you can connect DAB radio and television, in order to restore the digital signal in the video image.

Active DAB Antenna

DAB operating frequency in the choice of DAB working frequency is usually to consider, as frequency increases, the allowable distance between the launch pad to be reduced, so that the number of transmitters needed to increase the relationship between the square. (1) Band I (47 ~ 68MHz) in the band, due to the effect of ultra distance (E horizon) make the application received limited. In addition, in the band, especially the so-called “that noise”, such as subway interference for DAB, it is not the ideal working band. (2) Band II (87.5 ~ 108MHz) band is allocated to the terrestrial sound broadcasting use, it is now occupied by the FM radio. Obviously, DAB eventually be transmitted in the band. The band is not only assigned to sound broadcasting, and because it is close to 100MHz, for terrestrial digital sound broadcasting is particularly desirable. (3) The Band III band equally well suited for digital terrestrial sound broadcasting, particularly in the field test conducted DAB or implementation of the initial phase, for example, 233 ~ 230MHz Channel 12 television.

(4) Band IV / V (470 ~ 790MHz) in the UHF band, more than 80% for television coverage. If the synchronization network is small hive synchronization network, and the maximum driving speed is limited, then, UHF band for DAB, it is entirely possible applications. (5) L-band (1452 ~ 1492MHz) European Broadcasting Union (EBU) have pointed out that, with the work to cover the ground in the 1.5GHz range DAB digital synchronization network, although technically possible, but in the VHF (such as television Channel 12-Band compared to the number of transmitting stations to be 16 times larger, its running costs are also significantly higher, according to a rough estimate, about 4-fold to work when the VHF band. Further, in a car for a receiver, the system requires two antennas one for the VHF band, a band for 1.5GHz.L mostly for local coverage and small synchronous network. (6) S-band (2300 ~ 2600MHz) in order to achieve the same coverage and L-band, S-band to work on satellite transponder, the need for more power. at the same time, due to the higher masking, in the “shadow” region requires additional padding transmitter. in addition, due to the Doppler effect, so that these filler transmitters operate at the same frequency effectiveness is reduced. in general, the digital sound broadcasting in the S-band work is an expensive option, and provides only very limited technical possibilities.

Categories of 3G antennas and how to select 3G antenna


3G Antennas divided into: 1. omni-directiona 2.directional antenna 3.mechanical antenna 4.electrically tunable antenna 5. The dual-polarized antenna. The following will introduce people who are more concerned about the orientation and omni-directional antennas. Antenna Introduction:
Omnidirectional antenna
Omnidirectional antenna, that is, in the horizontal direction in Fig performance of 360 ° evenly radiation, which is usually referred to non-directional in the vertical direction in Fig performance of a certain width of the beam, the smaller the beam width under normal circumstances, the greater the gain. Omnidirectional antenna in a mobile communication system and general application suburban type large district stations, large coverage area.
Directional antenna
Directional antenna in the horizontal direction in FIG performance for a range of angles of radiation, which is usually referred to directional in the vertical direction in Fig performance of a certain width of the beam, with all the same antenna, the smaller the beam width , the greater the gain. Directional antenna in a mobile communication system generally used in urban residential system station type, small coverage and large subscriber density, high frequency utilization efficiency.
Directed into reflective and directed towards reflective type: common: Shining, Great Wall plates. Such an antenna depends mainly on the reflected signal reaches the oscillator to work.
Lead type: common: 8 Shining stacked wood is both the main oscillator signal source: Ling lead in front, behind the reflecting plate. Mainly by reflection, so the definition of the reflection type. Omnidirectional antenna: a common 9db.8db 7db.6db.5db 2db.
Directional antenna: Shining stack

Select 3G Antennas: the more antennas introduces the main emphasis on the transmitter, receiver and the principle that the individual emission principle is similar. Transmit power to be considered a problem, because if the antenna do not, under the power is too large, the emitted power emitted does not turn easily (simply is standing, leading power back to bite) damage to the machine . Friendly reminder: the use of high-power routing and network cards with friends, in an uncertain homemade antenna technology indicators, try to power down a little, just enough.
Choose the antenna, the key is to look at the environment. If it is 6 or less residential environment, the vision is not open, there was a barrier between 20-50 meters, it is recommended to use an omnidirectional antenna or tablet. Personal recommendation: 9db, 8db, 7db.
If it is high-rise, or cell edge environment (vision, signal in the distance). Recommended Yagi, 14db or more plates. Such an antenna is recommended in the range of 100-800 meters.
Using a distance of 1000 meters, indulgent, like urban and chat with friends, you can choose the grid, David – Star pot.
Select Antenna Material: For dimensioned drawings: Shining example, the reflective plate is increased to increase a little effect, the other would not have to change according to the drawings.

Be careful of this misunderstanding to buy a wireless router to see the number of antennas

“This wireless router has five antenna, can solve the problem through the wall of my house three rooms it?” Asked this question often encounter friends, do not know how to answer him. In fact, this problem exists among the vast majority of consumers, we all think to buy more antenna wireless router, the wireless signal will be very powerful. This is a big misunderstanding, the number of wireless antennas, wireless signal strength will not have an impact, today we have to reveal the “secret” of the number of wireless antennas and wireless signal strength.
Since when, we automatically put the number of wireless signal strength and wireless antennas linked to together? Open electricity supplier website wireless router sales page, we can find three and three more antennas wireless router, basically occupied the top few hot products. It also reflects the psychology of consumers now buy a wireless router, and “the more the better antenna positive signal.” Solve the problem of wireless signal at home, it is difficult simply by using a multi-antenna wireless router to solve the factors affecting the radio signal strength is multifaceted.
Wireless router there are multiple antennas sense, in fact, because MIMO technology. Whether two antennas products, or products antennas 3 are matched to X * X MIMO mode. Such as the current mainstream 300M wireless router, the pattern must be a 2×2 MIMO, it means that the two antennas is sufficient. If three or more of the three appeared in 2×2 MIMO antenna products, so that manufacturers mislead consumers. And with the popularity of dual-band wireless router, some manufacturers have done for each band independent external antenna, antenna some 4, 6 antenna wireless router is not surprising.

Importantly, the decisive factor is the quality of the wireless router signal transmission power of wireless router. States transmit power of wireless router has a predetermined, generally not exceeding 100mW, which is 20dBm (2.4GHz band). So we can see that, in fact, in accordance with national standards, the signal strength of the transmitting end is fixed. Whether it is a few antennas, it’s not going to change the transmission power, it will not affect the wireless signal coverage. In addition to the wireless router, we should look for the reason from the receiving end, the receiving end of the wireless card if sensitivity is not high, the wireless Internet experience will be poor.