In previous years, mmWave frequencies were used for niche military, aerospace, SATCOM and scientific research. This has changed, however, as emerging 5G, 60 GHz Wi-Fi, automotive radar and high speed data applications, operating in the tens to hundreds of GHz, are becoming common. The diversity of applications and the demand for higher frequency test systems are driving coaxial cable assemblies to the next level. These performance parameters for test cables extend beyond laboratory performance to address features specific to the new applications. From extremely tight tolerance for pristine laboratory conditions to rugged reliability for automated test facilities, the next generation of precision coaxial test cables operating at mmWave faces a wide range of “stiff” performance requirements.
Figure 1 mmWave applications extend from close proximity and high throughput device-to-device communications to last-mile broadband internet to the home. Source: Adapted from dailywireless.org.
Recent years have seen a rise in the use of the RF spectrum beyond 6 GHz (see Figure 1). Previously, the typical applications that ventured into mmWave frequencies were military, aerospace, SATCOM, weather and research science. These applications often used waveguide interconnects and, where necessary, could support the high costs and low volume of customized mmWave coaxial cables and connectors. Now, precision mmWave coaxial assemblies are in demand for a plethora of markets and applications. Some of the new markets include photonic and mmWave integrated circuits, 5G telecommunications, 60 GHz Wi-Fi, automotive radar, high speed data, military radar and mmWave imaging. Many of the new applications, especially 5G and SATCOM antenna arrays, require large numbers of coaxial assemblies for testing and operation, and some applications require these coaxial assemblies to operate under conditions considered extreme for interconnects usually designated as laboratory equipment. The latest demands are changing the performance and feature requirements for mmWave coaxial cable assemblies.
EMERGING APPLICATIONS
5G and 60 GHz Wi-Fi
Data consumption for mobile wireless users has been dramatically increasing. The latest generation of wireless standards is designed to meet the growing need for throughput, low latency, massive connections and flexibility to emerging needs. Necessarily, the frequencies for next-generation wireless communications must extend beyond the highly cluttered sub-6 GHz block, leading the FCC and other governments to set aside substantial mmWave spectrum for 5G, 60 GHz Wi-Fi (IEEE 802.11ad) and other emerging applications. The FCC’s defined frequency bands occupy 11 GHz of spectrum from 27.5 to 28.35, 37 to 38.6, 38.6 to 40 and 64 to 71 GHz.1 Opening spectrum to develop mmWave communication networks will enable more than high throughput device-to-device and base station-to-device connections—also last-mile residential services.
The implications of consumer, industrial, military, aerospace and SATCOM technology operating in the mmWave spectrum mean there is a greater chance for electromagnetic interference, either unintentionally or, possibly, by a malicious party. To design 5G networks and 60 GHz Wi-Fi systems to operate with the tight tolerances dictated by these upcoming standards, manufacturers, system designers and technicians need access to precision and cost-effective mmWave coaxial cables and connectors, with more features and accessibility than is currently available.
