Adapter and Terminator Considerations

As every adapter and termination can introduce unwanted insertion loss and reflections. Carefully choosing the right component can prevent unwanted signal degradation and potential damage to sensitive electronics. Adapters and terminations come in many forms, generally coaxial or waveguide for high power applications. Additionally, adapters can be more complex as the sizes and types of either end of an adapter may be different. Moreover, the adapter itself may introduce turns or bends.

The power and frequency range of an adapter must be scrutinized, especially if the adapters are waveguide to coaxial transitions. Waveguides naturally only enable a bandpass like range of frequencies to be carried with high signal fidelity, where coaxial technologies only have a cut-off frequency. However, the different coaxial connector types also have varying power and frequency capacities. If an adapter is transition between two different coaxial connector types, the frequency, power handling, PIM, insertion loss, and other parameters will be affected.

Terminations bear the brunt of dissipating potentially extreme amounts of RF energy within the device. Generally, terminations for high power applications will have a heat sinking metal body and possibly forced air thermal management. The impedance match and voltage-standing-wave-ratio (VSWR) of a termination are absolutely critical, as unpredicted reflections could lead to overpower and overvoltage conditions in the upstream electronics. This could be hazardous in the case of shunting a high power amplifier (HPA) to a termination that doesn’t meet adequate VSWR specs, as it could permanently damage the HPA.