There are many adjectives and specific ways of describing coaxial connectors, cable, adapters, and assemblies. Of the multitude of ways to describe coaxial adapters, one less common to hear is engineering-grade. There are many examples of general purpose, precision, high reliability (Hi-REL), high temperature, hermetic, vector network analyzer (VNA), low passive intermodulation (PIM), and other coaxial adapters designed with features and performance aspects suited to specific applications. Engineering-grade, however, implies a separate set of specifications and features more ideal for use by engineers and technical professionals that work directly with RF hardware and would understand the nuanced benefit of such Engineering-Grade Quality RF, Microwave and Millimeter Wave Adapters.
Firstly, general purpose coaxial adapters merely serve the purpose of adapting between coaxial genders or coaxial connector types. General purpose coaxial adapters are generally only built to meet the necessary requirements of the coaxial type and amongst several of these adapters may present a wide tolerance and may not be ideally suited to rugged conditions or repeated mating cycles. This type of coaxial adapter may have cost as the most significant consideration and are generally manufactured in high volumes of low-cost materials and workmanship. Hence, these adapters are best used in applications where overall performance and reliability are not significant constraints.
VNA or precision coaxial adapters are generally designed with test and measurement applications in mind where adapter performance is the priority. Precision adapters are either designed to be used as port preserving adapters at the ports of VNA, spectrum analyzer, signal generator, or other test equipment that sees a relatively high amount of connector cycling and the cost of the adapters is easily less than the cost of replacing the ports on the test equipment. These adapters are not typically designed to be particularly rugged but aren’t designed with very tight tolerances for consistent performance over typical laboratory environment ranges.
Engineering-grade coaxial adapters fall somewhere between general purpose and precision coaxial adapters. They are not as expensive nor quite as high performance as precision coaxial adapters but achieve superior performance levels, such as insertion loss, VSWR, and impedance tolerance, compared to general purpose adapters. A major emphasis for engineering-grade adapters is reliability and longevity, and these connectors are likely superior to all but Hi-REL and hermetic coaxial adapters in mating cycle lifespans and temperature resilience. This grade of coaxial adapter is often constructed with passivated steel for the body and coupling nut material with beryllium copper contact materials and gold over nickel plating for the contact surfaces. PPO is a typical insulation material due to the wide temperature stability of the material.