There are many situations in the laboratory, automated setup, and field where RF coaxial adapters are extremely useful for mating between different coaxial connector types. Installation or test environments where there is a mix of several coaxial connector types is where RF adapter kits shine. An RF Adapter kit is simply a series of RF coaxial adapters that are selected to mate between several key coaxial connector types.
An RF coaxial adapter is simply two coaxial connectors precisely assembled around a common housing with the both center conductors and outer conductors attached. Ideally a coaxial adapter will have minimal insertion loss and very low VSWR. There are high precision coaxial adapters that are generally made for test and measurement applications and offer extremely low insertion loss and VSWR. This is important for test and measurement applications, as any added insertion loss and VSWR can reduce the dynamic range of the overall test system. There are also other specialty RF adapters that include weather seals, are positioned at right angled, are radius right angled, are designed for bulkhead fixturing, or others.
Typically, RF Adapter Kits are combinations of adapters that are commonly used alongside each other. For instance, with millimeter-wave applications, 1.85 mm, 2.4 mm, and 2.92 mm coaxial connectors are very common. Hence, an RF Adapter Kit for millimeter-wave applications will likely include 1.85 mm RF Adapters, 2.4 mm RF Adapters, 2.92 mm RF Adapters, and possibly even 1.0 mm RF Adapters depending on the maximum frequency of the millimeter-wave system.
It is also common to see 3.5 mm and SMA adapters used in many test and measurement applications alongside N-type and BNC adapters. This is because SMA, N-type, 3.5 mm, and BNC are some of the most common coaxial connector types for frequencies below 18 GHz. 3.5 mm coaxial connectors are generally rated to 26.5 Ghz, with a maximum theoretical operating frequency of 34 GHz, however, a coaxial adapter is limited in frequency to the lowest maximum frequency between the two coaxial connector types.
It is also common to have RF adapter kits that are designed to mate between push-connect type coaxial connectors and threaded coaxial connectors for test and measurement applications as well as troubleshooting/maintenance. For example, MCX Adapters that mate to SMA, N-type, BNC, or 3.5 mm are often used for board mount push-connect MCX connectors that are either surface mount or end-launch. These types of low-cost and compact push-connect type connectors are often found on RF and high-speed digital circuit boards as test ports, which is why in quality/verification or rework stations, RF Adapter kits with push-connect to threaded coaxial connector types are very useful.