RF signal has its own characteristics, so the transmission of signal requires a special medium, the corresponding connector is also very special, here is the main description of the common rf coaxial connector, in accordance with gb11316-89, IEC169 standards, mil-c-31012 and other standards.     First. common coaxial connector and main performance table:     In addition to the above connectors, there are MINI BNC, SL16, C3, CC4 (1.0/2.3), SMZ (bt-43), MIM and other connectors, but mainly some of the company's models.     Second. Selection of common coaxial connectors     BNC is bayonet type for RF connections less than 4GHz and is widely used for instrument and computer interconnections.     TNC is thread connection, similar to BNC in size, operating frequency up to 11GHz, thread for vibration environment.     SMA is the most widely used, impedance of 50 and 75 ohms, 50 ohms, soft cable use frequency is lower than 12.4Ghz, semi-rigid cable up to 26.5 Ghz.     SMB connector is smaller than SMA in size and for fast connection inserts self-locking structure, commonly used for digital communication, is L9 replacement, 50 ohm to 4GHz, 75 ohm to 2GHz.     SMC is a threaded joint and other similar SMBS with a wider frequency range and is commonly used in military or high vibration environments.     N Type connector is screw, air insulation material, low cost, frequency up to 11GHz, often used in test equipment, there are 50 and 75 ohms two.     For dense connections, the MCX and MMCX connectors are small.     BMA for blind plug connections for low power microwave systems up to 18 GHz.     Each connector comes with military and commercial standards. The military standard is made by mil-c-39012, copper parts, PTFE insulation, inside and outside gold-plated, most reliable performance, but at a higher cost.     Commercial standard designs use inexpensive materials such as brass castings, polypropylene insulation, and silver coatings, which are less reliable.     The connector materials are brass, beryllium copper and stainless steel, and the center conductor is usually gold-plated to ensure low resistance and corrosion resistance.Military standards require gold plating on SMA and SMB, and silver plating on N, TNC and BNC, because silver is easy to oxidize and users prefer nickel.     Insulation material has polytetrafluoroethylene, polypropylene and toughened polystyrene, polytetrafluoroethylene insulation performance is the best, but the cost is higher.

    RF connectors may be small, but if you put together a sufficient number of connectors, as in a base station, you will find that these connectors and their associated cable fittings will form a network and become widely accepted.Therefore, if you can reduce the size of the connector while improving performance, simplifying installation, and reducing possible human errors, you have a good reason to replace it.These factors, as well as reduced PIM, are likely to result in familiar connector types such as N type connector and 7-16 DIN connector in microbase stations and small cells being almost or even substantially replaced by newer, smaller connectors, and the process is already under way.     Most components can be used in the back panel after the connector size is reduced, which is very important for space-limited applications.But even if these connectors may be small enough, they are not enough for wireless carriers that need more space in crowded device bunkers.In addition, applications that require high data rates, such as high-definition video, require large amounts of bandwidth, which connectors must adapt to.     Distributed antenna systems (DAS) are also hosts to a large number of digital, optical, and RF connectors that may be combined to more than 100 in a large installation.It is not feasible to replace all the connectors in existing analog DAS systems that transmit only RF signals over coaxial cables, but fortunately the field is growing fast, so a new first installation may use the latest connectors at the right price.Cable and telecoms companies have deployed hundreds of thousands of wi-fi hotspots as value-added services to customers, potentially making them a new, smaller alternative connector.Another area that could benefit from smaller connectors is the growing large market for portable RF test equipment that, in addition to its small size and high performance, requires a sturdy connector design to meet harsh field conditions.

    1. Power/level (dBm): the output capability of the amplifier, the general unit is w, mw, dBm     Note: dBm is an absolute power level expressed in decibels with 1mw as the reference value. Conversion formula:     Level (dBm)=10lgw     5W → 10lg5000=37dBm     10W → 10lg10000=40dBm     20W → 10lg20000=43dBm     It is not difficult to see from the above that every time the power is doubled, the level value increases by 3dBm     2. Gain (dB): the magnification factor, and the unit can be expressed in decibels (dB), That is: dB=10lgA (A is the power amplification multiple)     3. Insertion loss: the attenuation increased when a certain device or component is connected to the transmission circuit, and the unit is expressed in dB.     4. Selectivity: Measure the gain in the working frequency band and the suppression ability of out-of-band radiation. The -3dB bandwidth is the bandwidth when the gain is reduced by 3dB, and the same applies to -40dB and -60dB.     5. Standing wave ratio (return loss): the ratio of the antinode voltage to the node voltage (VSWR) in the traveling standing wave state     6. Third-order intermodulation: If there are two sinusoidal signals ω1 and ω2, many intermodulation components will be generated due to nonlinear effects. The two frequency components of 2ω1-ω2 and 2ω2-ω1 are called third-order intermodulation components. The ratio of the power of P3 and the signal ω1 or ω2 is called the third-order intermodulation coefficient M3, That is, M3 =10lg P3/P1 (dBc)     7. Noise figure: Generally defined as the ratio of output signal-to-noise ratio to input signal-to-noise ratio, which is calculated in decibels in actual use. The unit is dB.     8. Coupling degree: the power ratio between the coupling port and the input port, in dB.     9. Isolation: The ratio of the power of the local oscillator or signal leaking to other ports to the original power, in dB.     10. Antenna gain (dB): Refers to the ability of an antenna to concentrate its transmission power in a certain direction. Generally, the field strength E in the maximum radiation direction of the antenna is compared with the uniform radiation field strength E0 of an ideal isotropic antenna, and the multiple of the increase in power density is defined as the gain.      11. Antenna pattern: It is the range of electromagnetic waves radiated by the antenna in free space. The width of the directional pattern generally refers to the angle between the two points when the width of the main lobe drops half from the maximum value.     The E-plane pattern refers to the in-plane radiation pattern parallel to the electric field;     The H-plane pattern refers to the in-plane radiation pattern parallel to the magnetic field.  ...

    RF coaxial connector is installed on the cable or is a device inside a component, usually used for transmission line electrical connection or separation, is a commonly used electronic components, is a mechatronics products.     RF connector is generally installed on the cable or a kind of electronic components in the instrument, is used for transmission line electrical connection or separation of electronic components. Is a kind of mechatronics electronic components. Radio-frequency coaxial connector is installed in the cable or a kind of electronic products in the instrument, metal parts are generally made of copper material, the case multi-purpose lead brass, pin socket with beryllium bronze, with PTFE, that is, polytetrafluoroethylene as insulation material, coating mainly has gold plating, silver plating, nickel plating, plating ternary alloy and so on.The main technical indicators are characteristic impedance, insulation resistance, contact resistance, voltage standing wave ratio, insertion loss, third order intermodulation.

    BNC connetor is bayonet type, mainly used for rf connection less than 4GHz, widely used for instrument and computer interconnection     TNC connector is thread connection, similar to BNC in size, operating frequency up to 11GHz, thread type is suitable for vibration environment     SMA connetor is a threaded connection, the most widely used, impedance has 50 and 75 ohm two kinds, 50 ohm with the use of soft cable frequency is lower than 12.4Ghz, with semi-rigid cable up to 26.5 Ghz     SMB connector size is smaller than SMA, for the insertion of self-locking structure, for fast connection, often used in digital communication, is the L9 replacement, 50 ohm to 4GHz, 75 ohm to 2GHz     SMC connetor for threaded connections, other similar to SMB, with a wider frequency range, often used in military or high vibration environments     Type N connector is screw type, with air as insulation material, low cost, frequency up to 11GHz, often used in testing instruments, there are 50 and 75 ohms     The MCX and MMCX connectors are small in size and are used for intensive connections     BMA for blind plug connection of low power microwave systems with frequency up to 18GHz

    Compared with other electronic components, RF connectors have a short history. The UHF connector, which appeared in 1930, was the earliest RF connector.To the second world war, because of the war, with the development of radar, radio and microwave communication, the N, C, BNC, TNC connector series, such as medium, appeared after 1958 the miniaturization of products such as SMA, SMC, SMB connector, in 1964 established the United States military standard MIL - C - 39012 "standard of RF coaxial connector total", from then on, the RF connector began to develop in the direction of standardization, seriation, generalization.     The United States, the United Kingdom, France and other countries RF connector development technology is in a leading position, its design, production, testing, use of technology has become a complete set, tends to improve, not only formed a complete standard system, and raw materials, auxiliary materials, testing system, assembly tools and other has been standardized, and professional scale production.RF connector has gradually shown its own professional characteristics:     1. More varieties: more than 20 international series, more varieties.     2. Rely on mechanical structure to ensure electrical characteristics, is an mechatronics products, and other low-frequency connectors are fundamentally different.     3. The parts processing is mainly the turning machine processing, the assembly manual work is too much, it is difficult to carry out automatic assembly.     4. Product upgrading is slow.     5. It is an important part of the electrical connector and a labor-intensive product with certain technical content.     6. Product reliability, failure mode and failure mechanism are complex.     With the development of science and technology, RF connector appears more and more important, new technology and new products emerge in an endless stream.The rf coaxial connector industry will be a big market.

The Process of RF Cable Assembly : 1. Cutting line: check whether the specifications and models of the wires are correct;Whether the size meets the requirements;The cut must be level, not scratch the wire, the wire is not dirty and so on. 2. Skin peeling: check whether the skin opening is flat, and do not peel the damaged core wire, braided wire, etc., and whether the skin size is correct. 3. Marshalling treatment: trim the size correctly, trim flat, and do not hurt the core wire while trimming the marshalling. 4. Endothelial peeling: check whether the peeling opening is flat;Whether the peeling size is correct;There is no stripping core wire, broken copper wire;The insulator shall not come off when half stripped. 5. Sleeve shrinkage tube: check whether the size and type of shrinkage tube are correct. 6. Prepare soldering tin: check whether the temperature of the tin furnace is correct;Before preparing solder, whether the core wire copper wire is arranged, whether there is a fork, bending, discounting phenomenon;After preparing solder whether there are copper wire bifurcation, big head, copper wire and scalded insulation skin phenomenon. 7. Solder: check the temperature of the electric soldering iron is correct;Do not burn insulation skin, tin point should be smooth, wuxi tip, not fake welding, virtual welding. 8. Terminal pressing: confirm whether the specification of terminal and wire is correct;Whether the terminal is pressed too long or too short with or without bell-mouth, tilt, insulation and core wire exposed. 9. Terminal insertion: check whether the connector and terminal model are correct;Whether the terminal is damaged or deformed;Whether the terminal is missing, wrong, not in place and so on. 10. Line pressing: check whether the RF connector model is correct;Whether the alignment direction is correct;Whether the core wire is damaged, exposed copper or scalded;Whether the compression is in place. 11. Blow shrink tube: if the shrink tube is in good condition, do not burn the insulation skin. 12. Assembly shell: whether the shell is wrongly installed, whether there is any scratch or rough edge, whether there is any missing assembly part, whether there is any screw with unscrewed hair, oxidation, discoloration, looseness, etc., and no bad anastomosis after RF connector assembly;If the shell is oriented, it must be assembled according to the requirements. 13. Labeling: check whether the content of the label is correct, clear and without hyphenation;Whether the size of the label is correct;Whether the label is dirty or damaged;Whether the label is pasted in the correct position. 14. Tie tape: check whether the specification, color and position of tie tape are correct;No fracture or loosening. 15. Injection molding: check whether there is dirt on the mold, whether there is lack of materials, bubbles, bad adhesion, bad hardening, etc. 16. Plug molding: check whether the plug molding is damaged, uneven, lack of materials, rough edges, sundries,...

    In the field of wireless communication, microwave RF test cable is a kind of commonly used high-precision system test consumable, which is used in conjunction with test instruments.      Any DUT is located between the signal generator and the analyzer, and the bridge between the DUT and the instrument is the test attachment or test system.Do not neglect these test accessories, when possible, it is best to solidify these test accessories into a standardized measurement system.When the instrument supplier provides the complete machine, the maximum test cable will be provided in accordance with the highest operating frequency of the instrument.However, in the real test process, there will be a variety of different situations that require the use of different attachments, all of which will affect the accuracy of the measurement results, which requires the tester to have an in-depth understanding of the relevant test attachments.     When selecting the specification of the cable in the test system, in addition to considering insertion loss and VSWR, the stability of the cable must be better.In the frequency and microwave frequency bands, the commonly used cables are divided into semi-rigid cables, semi-flexible cables and flexible braided cables.Flexible cable as a "test - level" cable.Compared with semi-rigid and semi-flexible cables, the cost of flexible cables is relatively high, which is because more factors should be considered in the design of flexible cables.Flexible cables that are easy to bend multiple times and still maintain performance are essential for testing cables.Soft and good electrical indicators are a pair of contradictions, is also the main reason for the increase in costs.The flexible cable must be stable in amplitude and phase under bending conditions.     Generally speaking, single-stranded inner conductor cable is conducive to amplitude stability;Multi-strand inner conductor cable is conducive to the stability of the phase, it can be seen that only these two indicators are difficult to complete..Pay attention to the joint and cable connection parts of the process, which will affect the life of the cable.In this area, the traditional cable and connectors between a hard point of contact, it is easy to cause the fracture of the cable, which is most of the test engineer in the use of traditional cable testing the most headache problem in the process, and this is not a simple use heat shrinkable casing can solve, because this kind of fracture is often hard contact test cable after frequent bending, tension by cable transmission to hard contact, aging and rupture caused by hard contact.It is needless to say that the traditional flexible test cable without armoring can not effectively extend the service life of the test cable even if the enhanced heat-shrinkable sleeve is used at the cable and the joint because there is no armoring protection.     However, due to the gap betw...