Overview
Radio frequency (radio freency, abbreviated by rf), also known as radio frequency, wireless frequency, high weekly wave, is the frequency of concussion in the range of 3 khz to 300 ghz, which corresponds to the frequency of radio waves, as well as the frequency of communication electricity carrying radio signals. Rf is usually used to refer to electron convulsions rather than to mechanical convulsions, yet mechanical rf systems still exist (e. G. Mechanical filters and radio-frequency microprocessors (rf mems) systems)。
While radio frequency is defined as a frequency, it is often used in day-to-day use as synonyms for radios to facilitate the description of wireless communication systems, such as radio frequency recognition。
Radio frequency tag system
Composition
Label (tag, i. E. Radio frequency card): composed of coupling elements and chips, the labels containing an inner antenna for communication between the rf antennas
2. Readers: equipment to read (and write in the reading and writing card) label information
3. Antenna: transmit radio frequency signals between labels and readers. Some systems are also linked to external computers (upper-space master system) through rs232 or rs485 interfaces of readers。
Integration
As the development of a highly integrated system continues, the integrated range of radio frequency ranges has expanded from a mere integration of communication, navigation and recognition functions to an integration of all radio frequency sensor functions and an integration of some mission systems to achieve the ultimate goal of physical integration of systems, resource management and information integration。
Combined content
The integrated content of the radio frequency system includes the integration of resources, functions and information. Resource integration refers to integrated design that provides optimal resource allocation using an integrated antenna design, miniaturization of the front end of the radio frequency and the channel, universalization design and signal processing based on software definition functions, and data processing. By dividing the functions of the internal resources of each sensor, it can be seen that the functions of the sensor can be divided horizontally into apertures, receivers, pre-processing, sensor processing and mission processing, the sharing of the resources of the radio frequency can be achieved using generic standard modules, and the functions of the different sensors can be accomplished by reconfiguring。
When the system is integrated in its resources, the advantages of radio-frequency compatibility and invisibility can be realized within the platform, as well as the advantages of coordinated detection, coordinated attack and coordinated defence within the system. The user-oriented experience and operational needs provide the best sensor configuration and significantly enhance new system capabilities through integrated controls based on independent sensors。
The integration of information is intended to provide the best information. As field environments and tasks become more complex, the platform acquires an ever-increasing volume of information. Multi-source data situation generation, multi-source data linkages, complementary information integration, redundant information integration, etc., are achieved through integrated information processing and integrated control, extracting the best information and providing managers with complementary decision-making to support smart decision-making。
Integrated approach
The integrated approach of the radio frequency system includes, inter alia, antenna aperture integration, front-end radio frequency integration, signal information processing resource integration, time frequency harmonization, virtual sensor functionality, radio frequency compatibility and sensor movement management. Integrated design, ranging from the reuse, sharing and re-engineering of antenna resources to the high integration of hardware resources, expansion of sensor functions, backup, re-engineering, radio frequency invisibility, radio frequency compatibility, sensor management, etc., to achieve integration of radio frequency system resources, functions and information。
Antenna integrated design can be carried out in three dimensions: broadband, multifunctional, and co-acoustic. In this context, broadband design refers to antennas that are not classified by function, but rather to broadband design that achieves the sharing of multiple functions; multifunctional design, which refers to a shared antenna that is close to multiple frequency bands, which ensures the compatibility of multiple functions through radio-frequency control and sensor management techniques; and co-perigence design, which refers to physical multiple antenna co-perigence installation, the reduction of dispersive sources and the installation of maintenance caps。
At the heart of the integration of radio frequency systems is the integration of the front end of the radio frequency, which, in addition to achieving the sharing of radio frequency reception and launch channels, is based on the adoption of an open radio frequency system structure, the modularization and standardization of radio frequency channels and the enhancement of the tolerance and re-construction capabilities of the radio frequency channels。
Division
In the international telecommunication union definition of radio frequency classification:
Very low frequency (vlf): 3-30 khz
Low frequency (lf): 30 ~ 300 khz
Medium frequency (mf): 300-3000 khz
Hf (hf): 3-30 mhz
Vhf: 30 ~ 300 mhz (mhz)
Uhf: 300 ~ 3,000 mhz
Uhf: 3-30 ghz
Very high frequency (ehf): 30 ~ 300 ghz
Professional terms
Power/level (dbm): output capacity of amplifiers, typically w, mw, dbm
2. Gains (db): i. E., magnification multipliers, expressed in db。
Note: dbm is the absolute power level expressed as a deutsche using 1 mw as the baseline。
Conversion formula:
As can be seen from above, for every doubling of power, the level increases by 3 db, i. E. Db = 10 lga (a is the power magnification multiplier)
3. Interruption: when a device or component is connected to a transmission circuit, the unit is expressed as db。
4. Selective: measuring gains and inhibitions of external radiation in working bands。
5. Beacon (return to loss): ratio of abdominal to abdominal voltage (vswr) at wave state
6. Third tier: m3 = 10 lg p3/p1 (dbc)
7. Noise coefficient: is generally defined as the input-to-output ratio, which is actually calculated using neutralized to betes。
8. Alignment: power ratio of the coupling port to the input port, in db。
9. Segregation: power of current oscillation or signal leaking to other ports in proportion to its original power, in db。
Antenna gain (db): refers to the ability of the antenna to centralize radiation in a given direction with the launch power。
Antenna orientation map: is the extent to which electromagnetic waves from antenna radiation exist in free space。
12. Antenna ratio: is the ratio of the maximum positive gain to the maximum reverse gain, expressed as decibels。
13. Single worker: also known as single-frequency single-work system, i. E. The same frequency is used for transmission and transmission。
14. Double work: also known as the round-trip system, i. E., two different frequencies are used for transmission and transmission。
15. Amplifiers: (amplifier) circuits for signal magnification。
16. Filters: (filter) parts or devices that contain useless frequency signals by means of a useful frequency signal
17. Decompositioners
18. Concorders: devices to extract some of the signals from the backbone channel。
Load: the element/unit, component or device for receiving electrical power at a circuit (e. G. Amplifier) or at an electrical output port is collectively referred to as the load。
Ringers: devices that transmit signals in a single direction。
21. Turnback: a device that connects different types of transmission lines。
22. Feedback: a transmission line for high-frequency currents。
23. An antenna
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Radio-frequency communications applications
Medical applications
Identification system applications
