RF Adapters Information

RF adapters are used to connect different waveguides and/or coaxial cables. They are passive devices that direct radio frequency (RF) signals with minimal return loss.

Coaxial cables are electrical cables with three layers: a conductor material within an insulating layer within a tubular shield. The term coaxial comes from the fact that the two protective layers share the same geometric axis. It is used as a transmission line for radio frequency signals.

Waveguides are structures which guide and direct different types of waves. In the case of radio waves, a hollow and conductive metal pipe is used.


There are three main types of RF adapters: coaxial, waveguide, and coaxial/waveguide.

  • Coaxial RF adapters are used to connect two different types of coaxial cable or to terminate a coaxial port. 
  • Waveguide RF adapters are used to connect two different types of waveguides or to terminate a waveguide port. 
  • Coaxial / waveguide RF adapters connect a coaxial cable to a waveguide or vice-versa. 

Product Specifications

Product specifications to consider when selecting RF adapters include frequency range, maximum input power, voltage standing wave ratio (VSWR), return loss, and adapter style. The return loss of an adapter is a measurement of the match between the impedance of the adapter and the system impedance. VSWR is a measure of the amount of RF power reflected back to the signal source because of impedance mismatches.  Frequency range, maximum input power , and adapter style are all dependent on the system design for which the adapter is being used.

Adapters come in a large array of different connector types and brands which vary based on size, specifications, and individual product features. The GlobalSpec SpecSearch Database contains listings and information on many of these types.

Engineering Calculators Related to RF Adapters