The basic structure of a coaxial connector includes: the center conductor (male or female center contact); the dielectric material outside the inner conductor, or called an insulator; the outermost part is the outer contact, which acts as the outer shield of the coaxial cable The same function, that is to transmit signals, as a shielding or circuit grounding element. Coaxial connectors are mainly divided into: SMA, SMB, BNC, TNC, SMC, N type, BMA, etc.

1. Common sense of RF coaxial connector

Male: Male connector, thread inside, inside is needle, sometimes also called "J" port. Such as TNC(M)

Female: Female connector, thread on the outside, inside is a hole, sometimes also called "K" port. Such as SMA(F)

RP: Reverse Polarity means that the head and the needle inside are opposite.

Bulkhead: It is the connector of the lockable screw on the board including washer, screw cap and retaining wall (such as SMA FEMALE BULKHEAD), generally used for board cards

PCB: It is a connector with feet that can be soldered on the board. (Such as SMA FEMAL PCN).

Panel: It is a connector with screw holes that can be locked on the board with screws. (Such as SMA PANEL MOUNT) There are usually 4 holes and 2 holes.

2. Describe the commonly used elements of RF connectors

1. Connector type: SMA, SMB, BNC, TNC, SMC, N type, BMA, etc.

2.Characteristic impedance: 50 ohm standard 50 or 50 not standard, 75 ohm standard 75

3. Method of contact key: male, female

4. Shell type: straight type: no standard; curved type: W

5. Installation form: flange: F nut: Y welding: H

6. Wiring type: suitable cable model, requirements for inner diameter and outer diameter, etc.

7. Attenuation: Corresponding to the signal strength attenuation caused by the passage of radio frequency signals in different frequency bands

8. Thread type: external thread, internal thread

Remarks: Generally, the connector on the equipment side is a female male thread, and the cable side is mostly a male female thread.

3. Common transmission cable connectors

Considering the effect of the feeder, of course the thicker the better. However, the thicker it is, the more expensive it is, and the price of the connector is also expensive.

Come more troublesome. So, choose the feeder and just "appropriate".

3.1, SMA

SMA series connector is a kind of coaxial connector with a wide range of small threaded connections. It has a long life, superior performance and high reliability. It is widely used in the RF coaxial cable or microstrip of microwave equipment and digital communication equipment.

It is often used for the GPS clock interface on the single board and the test port of the radio frequency module of the base station on wireless equipment. At this stage, the most common interface of handheld walkie-talkies is already common.

3.2, SMB

SMB type coaxial connector is a small push-in locking radio frequency coaxial connector, which has the characteristics of small size, light weight, convenient use, and excellent electrical performance. It is suitable for connecting coaxial cables in the high-frequency loops of radio equipment and electronic instruments. use. It is often used in wireless equipment to connect the base station side E1 transmission cable to the base station DDF small transmission box.

3.3, BNC

BNC type coaxial connector is a bayonet type radio frequency coaxial connector, which has the characteristics of fast connection and reliable contact. It is widely used in the field of radio equipment and electronic instruments to connect radio frequency coaxial cables. Nowadays, it is used in monitoring, radio, detector and other equipment that often needs to be replaced at any time.

3.4, TNC

TNC type coaxial connector is a threaded connector type radio frequency coaxial connector. It has the characteristics of wide working frequency, reliable connection and good seismic performance. It is used to connect radio frequency coaxial cables in radio equipment and instruments, and is especially suitable for vibration conditions. Mobile communication equipment.

3.5, N type

The N-type coaxial connector is a medium and high-power connector with a threaded connector structure. It has the characteristics of strong shock resistance, high reliability, excellent mechanical and electrical performance, etc., and is widely used in radio equipment and radio equipment under vibration and harsh environmental conditions. Used to connect radio frequency coaxial cable in the instrument.

Commonly used in GPS antenna feeder, radio frequency connection of radio frequency module, lightning arrester, power splitter, combiner and other connectors.

3.6, DIN

DIN type (also called 7/16 or L29) series coaxial connector is a larger threaded connector, which has the characteristics of sturdiness, stability, low loss, high working voltage, etc., and most of them have waterproof structure, which can be used outdoors as medium and High-energy transmission connectors are widely used in microwave transmission and mobile communication systems.

 
Commonly used in base station antenna feeder connectors, antenna connectors, etc.

Four, some basic knowledge of antenna

It is said that the transmission line has 50 or 75 ohms, so why?

For coaxial cables, we are mainly concerned with the two issues of power transmission and energy attenuation during transmission. In order to maximize the power transmitted by the coaxial line, it is necessary to make the inner and outer conductors of the coaxial line have a ratio. For a coaxial line with air as the medium, when the outer radius/inner radius = constant E square, the transmitted power is the largest. The characteristic impedance at this time is 30Ω. When the outer radius/inner radius=3.59, this attenuation is the smallest, and the characteristic impedance at this time is 77Ω. In order to have both, the compromise value is 50Ω. Of course, 75Ω coaxial cables are also in use in some equipment, such as cable television systems.

xinxie RF Coax Connectors Includes: