Plastic fiber shows promise for carrying mmWave signals

Santa Clara, Calif. — While millimeter wave (mmWave) signals are part of 5G’s wireless infrastructure for carrying high-bandwidth data, it’s not the only use. At DesignCon 2020, Joy Laskar, CEO of Maja Systems, presented a paper where he explained how a surface-mount mmWave antenna can launch signals into inexpensive plastic fibers for data transmissions from a few centimeters to several meters.

That distance, according to Laskar’s paper Millimeter-Wave Surface Mount Antennas for High-Speed Plastic Fiber Data Transport, “Millimeter-wave data transport based on low-cost plastic ﬁbers ﬁlls an important gap between optical and metal-based transport, providing bandwidth and reach superior to metal with less power consumption than optical.” This concept uses radio waves coupled to plastic fiber.

The trick is the get good coupling between an antenna and the fiber, something Maja Systems claims to have solved. Using Maja’s 60 GHz radio IC and its surface-mount antennas, Laskar showed data rates of 1 Gbps at 17 m and 2 Gbps at 16 m (Figure 1).

Figure 1. Test show data rates of 2 Gbps over 16 m of plastic fiber and 1 Gbps at 17 m.

Figure 2 shows a slide that explains the radiated field pattern of the SMT antenna. A plastic fiber fits over the antenna, picking up the signal without the need for a connector.

Figure 2. This plot shows the signal strength from a Maja Systems SMT antenna Theta as a function of Phi.

Figure 3 shows a demonstration of the antenna driving plastic fiber using a vector-network analyzer. Laskar explained to 5GTW: “The demonstration operates as a wireless cable: a compact millimeter-wave surface mount helix antenna combined with 60 GHz integrated radios and low-cost synthetic fibers, which establishes a reliable, simple, low cost and error free interconnect system. This demonstration achieves error-free transmission without connectors using our (patent-pending) surface mount helical antenna, enabling efficient coupling and wide bandwidth with meter-range copper-grade gigabit transport. This represents a novel and non-traditional application of mmWave technology and will enable low-cost data transport in the centimeter to meters range, complementing current transport technologies based on optical fibers, coaxial flyover assemblies, and PCB traces.”