First, the antenna: (antenna)
Or a high-frequency current is converted to a waveguide in the form of electromagnetic energy into a predetermined direction to the electromagnetic wave emitted from a certain direction, or reduction of an apparatus of a high frequency current.Second, the antenna Category:
(1) By Application: can be divided into communications antennas, TV antennas, radar antennas;(2) Working frequency classification: can be divided into short-wave antenna, FM antenna, microwave antennas;
(3) classification by directional: can be divided into omnidirectional antennas, directional antennas;
(4) shape classification; can be divided into linear antennas, planar antennas.
Third, the omnidirectional antenna
Omnidirectional antenna, i.e., in the horizontal direction in Fig evenly 360 ° for performance of radiation, which is usually referred to non-directional in the vertical direction in Fig performance of a certain beam width, the smaller the beam width under normal circumstances, the greater the gain.Four directional antenna
Directional antenna in the horizontal direction at a certain angle range performance diagram 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 directional antenna beamwidth smaller , the greater the gain.V. gain
Gain means: input power equal conditions, the ratio of the actual and the ideal antenna radiation elements in a space produced at the same point in the signal power density. It describes a quantitative concentration of the radiation antenna input power level. Gain apparently graph has a close relationship with the antenna, the narrower the direction of the main lobe, side lobe is smaller, the higher the gain. Physical meaning can be understood as generating a gain at a certain distance from a point of the signal of a certain size, if an ideal point source as the non-directional transmitting antenna requires input power of 100W, and with a gain of G = 13 dB = 20 and a directional antenna as the transmitting antenna, input power only 100/20 = 5W. other words, the gain of an antenna, the radiation effect on the maximum radiation direction, the ideal and non-point source with directivity ratio, the larger the input power factor.
A means: SWR SWR ≤ 1.5 under the conditions of the operating band width of the antenna;
One means: antenna gain reduction within 3 db bandwidth of the scope.
In a mobile communication system, typically defined by the former, particularly, the band width of the antenna is the standing wave ratio SWR of the antenna is not more than 1.5, the operating frequency range of the antenna. Generally, the bandwidth on each of the working frequency, the antenna performance is different, but the deterioration of the performance difference is acceptable.
· Why 3G license: According to Chinese market space, to promote competition in the Chinese telecom market; efficient use of frequencies; specification paragraph number, paragraph number will be from 15 to 18; controlling operating costs related to the development of the mobile communications industry. Any operators in order to get 3G licenses, should have the strength of five aspects: First, the network strength. Second, the need for capital strength. Third, the technical strength. Fourth, the business strength. Fifth, the user strength. China Telecom, China Netcom's PHS system, China Mobile, China Unicom. So what you say is wrong, not the package does not include the question of who is the manufacturer you say is certainly no such strength.
· 3G standard three standard
TD-SCDMA:The full name of Time Division - Synchronous CDMA (Time Division Synchronous CDMA), the standard proposed by the Chinese 3G standard.
Features: In the spectrum efficiency, has a unique advantage to business support flexibility. Internet speed is four times CDMA1X be free at T network and G network conversion.
WCDMA:Also known as WCDMA, called the Wideband CDMA, also known as CDMA Direct Spread, meaning wideband code division multiple access, which is based on the GSM network developed 3G technology standard, is Europe's proposed broadband CDMA technology.
Features: There is a high spreading gain, larger space for development, global roaming capabilities of the strongest, but the technology is mature in general.
CDMA2000:CDMA2000 is a narrow-band CDMA (CDMA IS95) technology evolved wideband CDMA technology, also known as CDMA Multi-Carrier, made by Qualcomm as the leading company in North America, South Korea is now the leader of the standard.
Features: You can upgrade from the original structure CDMAOne directly to 3G, low construction costs.
· The development of global 3G root condition: the world has 67 commercial 3G networks, up to August this year, 45 countries around the world have issued 146 permits, 138 are now effective.
Sixth, the antenna operating frequency range (bandwidth)
Both the transmitting antenna or the receiving antenna, which are always in a certain frequency range (bandwidth) of work, the antenna bandwidth has two different definitions:A means: SWR SWR ≤ 1.5 under the conditions of the operating band width of the antenna;
One means: antenna gain reduction within 3 db bandwidth of the scope.
In a mobile communication system, typically defined by the former, particularly, the band width of the antenna is the standing wave ratio SWR of the antenna is not more than 1.5, the operating frequency range of the antenna. Generally, the bandwidth on each of the working frequency, the antenna performance is different, but the deterioration of the performance difference is acceptable.
Seven, 3G-related knowledge introduction
· What is the 3G licenses: business license and other wireless communications and international Internet multimedia communications with a new generation of mobile communication systems. Just as there are various sectors of the business license, and must have permission for national authorities operating this business· Why 3G license: According to Chinese market space, to promote competition in the Chinese telecom market; efficient use of frequencies; specification paragraph number, paragraph number will be from 15 to 18; controlling operating costs related to the development of the mobile communications industry. Any operators in order to get 3G licenses, should have the strength of five aspects: First, the network strength. Second, the need for capital strength. Third, the technical strength. Fourth, the business strength. Fifth, the user strength. China Telecom, China Netcom's PHS system, China Mobile, China Unicom. So what you say is wrong, not the package does not include the question of who is the manufacturer you say is certainly no such strength.
· 3G standard three standard
TD-SCDMA:The full name of Time Division - Synchronous CDMA (Time Division Synchronous CDMA), the standard proposed by the Chinese 3G standard.
Features: In the spectrum efficiency, has a unique advantage to business support flexibility. Internet speed is four times CDMA1X be free at T network and G network conversion.
WCDMA:Also known as WCDMA, called the Wideband CDMA, also known as CDMA Direct Spread, meaning wideband code division multiple access, which is based on the GSM network developed 3G technology standard, is Europe's proposed broadband CDMA technology.
Features: There is a high spreading gain, larger space for development, global roaming capabilities of the strongest, but the technology is mature in general.
CDMA2000:CDMA2000 is a narrow-band CDMA (CDMA IS95) technology evolved wideband CDMA technology, also known as CDMA Multi-Carrier, made by Qualcomm as the leading company in North America, South Korea is now the leader of the standard.
Features: You can upgrade from the original structure CDMAOne directly to 3G, low construction costs.
· The development of global 3G root condition: the world has 67 commercial 3G networks, up to August this year, 45 countries around the world have issued 146 permits, 138 are now effective.
Eight, telecommunications technology Glossary:
What is CDMA and CDMA2000? CDMA is an acronym for Code Division Multiple Access (Code-Division Multiple Access) technology in recent years, appearing in digital mobile communication process, an advanced wireless spread spectrum communication technology, it is able to meet the market for mobile communication capacity and high quality requirements, high spectrum efficiency, better voice quality, confidentiality, call drop rate, electromagnetic radiation is small, large capacity, covering wide coverage and other characteristics, can significantly reduce investment and reduce operating costs.
CDMA was first launched by Qualcomm, and the same GSM, CDMA also has two generations, 2.5G and 3G technologies. China Unicom will launch later this year belong to the 2.5 generation CDMA technology. CDMA is considered the first choice for the third generation mobile communication technology, the current standards are WCDMA, CDMA2000, TD-SCDMA.
What is CDMA2000?CDMA2000 is the name used to refer to TIA standards organization on behalf of a third-generation CDMA. Applicable to the TIA specification called 3G CDMA IS-2000, the technique itself is called CDMA2000.
What is CDMA2000?CDMA2000 is the name used to refer to TIA standards organization on behalf of a third-generation CDMA. Applicable to the TIA specification called 3G CDMA IS-2000, the technique itself is called CDMA2000.
The first stage is also known as CDMA2000 1x, which enables existing IS-95 system has a communications company able to double its overall system capacity, and increase the data rate up to 614kbps. Higher than the CDMA2000 1x technological advances include 1xEV (high data rate). Launched by the QCT MSM5000 chipset solution is backward compatible with CDMA2000 cdmaOne (IS-95 CDMA). CDMA2000 standard developed by the 3GPP2 organization versions include Release 0, Release A, EV-DO and EV-DV, Release 0 of the main features is adopted based on ANSI-41D core network, adding support packet services in the radio access network and the core network network entities, this version has been stabilized.
China Unicom's CDMA upcoming opening of the second phase project is using this version, the highest single-carrier downlink rate can reach 153.6kbit / s. Release A strengthening Release 0, the highest rate of single carrier can reach 307.2kbit / s, and supports concurrent voice and packet services. EV-DO with a separate carrier to support data services, can be a standard 1.25MHz carrier, while providing voice and high-speed packet data services, the highest rate of up to 3.1Mbit / s.
What is 3G:3G, third generation digital communications. In 1995 came the first generation analogue phones (1G) can only make voice calls; 1996-1997 appeared the second generation GSM, TDMA digital formats, such as mobile phones (2G) will increase the receive data, such as receiving e-mail or pages; third-generation main difference with the previous two generations is to enhance the speed of transmission of voice and data, it can better achieve seamless roaming across the globe and deal with images, music, video streaming and other forms of media, providing a variety of information services including web browsing, conference calls, e-commerce, but also consider the good compatibility with the existing second-generation system. To provide this service, the wireless network must be able to support different data transfer speeds, which means that the indoor, outdoor, and driving environment can support at least 2Mbps (megabits / second), 384kbps (kilobits / second) and 144kbps transmission speed. (This value will vary depending on the network environment).
The so-called 3G standard, the International Telecommunication Union (ITU) to determine the current total of four global 3G standards, they are WCDMA, CDMA2000 and TD-SCDMA and WiMAX. Where TD-SCDMA is China's self-developed 3G standard proposed.
What is 3G:3G, third generation digital communications. In 1995 came the first generation analogue phones (1G) can only make voice calls; 1996-1997 appeared the second generation GSM, TDMA digital formats, such as mobile phones (2G) will increase the receive data, such as receiving e-mail or pages; third-generation main difference with the previous two generations is to enhance the speed of transmission of voice and data, it can better achieve seamless roaming across the globe and deal with images, music, video streaming and other forms of media, providing a variety of information services including web browsing, conference calls, e-commerce, but also consider the good compatibility with the existing second-generation system. To provide this service, the wireless network must be able to support different data transfer speeds, which means that the indoor, outdoor, and driving environment can support at least 2Mbps (megabits / second), 384kbps (kilobits / second) and 144kbps transmission speed. (This value will vary depending on the network environment).
The so-called 3G standard, the International Telecommunication Union (ITU) to determine the current total of four global 3G standards, they are WCDMA, CDMA2000 and TD-SCDMA and WiMAX. Where TD-SCDMA is China's self-developed 3G standard proposed.