Too many types and confused about what you need to buy? Well, you are not alone...Many electronic hobbyists and even engineers have confusion about this. If not careful, you may end up with an SMA male + RP-SMA female and will not be able to make the connection ! I have shown the picture of each connectors below, so that we all can be clear about what we need for proper connectivity.
Like most of the connectors, the SMA connectors are also classified as "male" or "female" based on where the threads are. The male connectors has inner threads and the female connector has outer threads. Yes, it is that simple. No need to confuse any more. For example, take the F-type connector which is used in CATV and satellite TV widely. The F-connector with outer thread is a female connector and the one with inner thread is the male connector. The same is true for the N-type connector also.
Generally the characteristic impedance of all types of SMA connectors is 50 ohms. Most of the SMA connectors are rated from DC to 18 GHz. There are some special SMA connectors which can work up to 26 GHz, but above this frequency different types of connectors are preferred for better performance. The dielectric material used inside the SMA connector is polytetrafluoroethylene (PTFE).
Usually an SMA connector is good for about 400 to 600 connections or mating cycles, if you use the proper torque while connecting together. For hand tight use, it may work for up too 1000 or more mating cycles depending upon the material used for making these connectors.
The most important thing one should take care while mating RF connectors is NOT to rotate the center pin. For example, when you connect an SMA male and Female connectors together, rotate the metal nut portion of the male connector. DO NOT rotate the female SMA connector. Similarly, when you mate an RP-SMA Male connector to an RP-SMA Female connector, rotate the Male connector nut. This is to avoid the rotation of the inner pin which is in contact with the inner receptacle which may damage the receptacle.
-VgR
