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A radio frequency connector is an electrical connector used to connect television monitors to antennas or videocassette recorders. Technically speaking, a RF connector is an electrical connector designed to work at radio frequencies in the multi-megahertz range. Therefore, RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers.
Structure
A radio frequency connector consists of threaded leads. A center conductor is shielded when a shielding connector cap, having a threaded inner portion, screws onto the threaded leads. Hence, RF connectors are typically used with coaxial cables and are designed to maintain the shielding that the coaxial design offers. As per its mechanical working is concerned, it allows a fastening mechanism (using thread, bayonet, braces, push pull) and springs for a low ohmic electric contact, at the same time, sparing the gold surface thereby allowing above 1000 reconnects and reducing the insertion force.
Standard types
* BNC (Bayonet Niell-Concelman)
* C connector (Concelman)
* GR connector (General Radio)
* F connector, used for U.S. domestic television installations
* IEC 169-2 connector, also called Belling Lee connector used in the UK and some other countries for domestic television installations and as FM connector for radio. It is standardised in EN 60169-2.
* Motorola connector, standard AM-FM antenna connector used for automotive radios
* Musa connector, a 75-ohm connector used in telecommunications and video
* N connector (Niell)
* TNC connector (Threaded Niell- Concelman)
* UHF connector (e.g. PL-259/SO-239)
BNC or Bayonet -Neill - Concelman, is a locking mechanism and its main function is to terminate coaxial cables. They are largely used in cable interconnections and network cards in 10base2 thin Ethernet networks. BNC connectors are the alternatives to RCA connectors. BNC connectors are ideally suited for both analog as well as for serial digital interface signals in professional video connections. They are also used in amateur radio antenna connections and in all electronic test equipment.
F connectors have an impressive performance of up to a frequency of one giga hertz. The center wire of a coaxial cable is used as the male connector pin, thus the F connector is inexpensive. The connector body of the male connector is typically crimped onto the exposed outer braid. 3/8-32 thread are commonly found in a female connectors. A matching threaded connecting ring is usually found in most male connectors. Applications of F connectors are in satellite television, cable TV connections in DOCSIS cable modems. RG -6 tri shield cables are commonly used in F connectors.
The N connector is a threaded type of RF connector. The N connector is the first connector that had the potential to carry microwave frequency signals. This connector was invented in the early 1940s by Paul Neil. Coaxial cables are joined together by using N connectors
The threaded version of the BNC connector is the TNC connector. The impedance value for the TNC connector is 50 ohm. Operations of TNC connector are more effective when the frequency spectrum is in the range of 0-11 GHz. At microwave frequencies, TNC connectors have superior performance over BNC connectors. The reverse polarity of the TNC connector can be achieved by introducing female contacts into plugs and male contacts into the jacks. Usually female and male contacts are fitted into jacks and plugs respectively before reversing the polarity. They are widely used in radio and wired applications.
UHF connectors are capable of handling RF power levels above one kilowatt. The operating range for UHF connectors is the ultra high frequency range, which is 300 to 3000MHz. UHF connectors are widely used in amateur radios, band radios, and marine VHF radios. N connectors and BNC connectors are the alternatives for UHF connectors due to their superior performance.
Miniature types
* Miniature BNC connectors
* DIN 47223 connectors
Miniature rf connectors are classified into miniature BNC connectors and DIN 47223 connectors.
The DIN 47223 connector operates at a frequency of 7.5GHz. This connector utilizes gold or silver plates and rubber gaskets.
Sub-miniature types
* MCX connector
* FME connector
* SMA, SMB, and SMC connectors
MCX, FME, SMA, SMB and SMC are the sub classifications of sub miniature RF connectors.
The impedance value for MCX family connectors are 50 ohm. European standard CECC 22220 is followed in MCX connectors. The rated frequency range is 0-6GHz. These connectors are designed to allow a minimum of 500 interconnect cycles.
In SMA (Subminiature A) connectors, the dielectric of the cable is carried without any air gaps directly to the interface. Hundreds of interconnect cycles are attainable if performed carefully. Joining the connectors is vital since it has a significant impact on the performance of the connector. It is preferable to analyze the female end to ensure the condition of the socket before making a connection. The rated frequency for a standard SMA connector is 12.4 GHz. The rated frequency can even go higher if the connector is designed well with greater loss and lower return loss. The reflection coefficient is higher for standard SMA connectors.
The subminiature B (SMB) is constructed for 500 interconnect cycles. It is a snap-mount connector. The rated frequency is 4 GHz for SMB connectors. Insertion loss is about 0.3db at rated frequencies. Due to large insertion loss, the SMB connector is not generally used in critical low noise microwave RF interconnects. However, it isapplicablein other signal delivery applications. Without moding, SMB connectors can be used up to 10 GHz.
The subminiature C is a threaded type of interface RF connector. It is smaller than an SMA connector and is well suited to applications where size is a constraint. No gaskets are provided in SMC connectors. Threads available in SMC connectors are in the range 10-32.SMC and are excellent alternatives for SMB connectors, where vibration is a problem.
Precision types
· APC-7 connector
APC-7 is a precision type and sexless RF connector. APC or Amphenol Precision Connector. offers the lowest reflection coefficient. The advantage of the sexless design of amphenaol rf connectors are used in most demanding applications such as metrology and calibration. These connectors are capable of delivering a few hundreds of interconnect cycles untill mating surfaces are kept clean.
Applications of RF Connectors
- Used in dividers, mixers, amplifiers, trimmers, and attenuators.
- Used in critical space applications, PCMCIA cards and other smallhand-held communication devices.
- Used in GPS, wireless communications, and automotives.
- Used in cable TV, MATV, CCTV and related consumer television products.
- Used in telecommunications and cable television industry applications.
- Used in IR and convection reflow soldering.
- Used in hybrid fiber coax networks,high speed modems, and CIMs, NTSC TV antennas and other applications.
- Used in high power communications.
- Used in military and commercial applications.
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