Feature: Wireless Technology
Figure 1: Live demonstration of the sub-THz dual polarisation OTA link
Doubling data at sub-THz:
One link, two polarisations, twice the data By, Greg Rankin, freelance technology writer
T
he promise of the sub- terahertz (THz) region of the electromagnetic spectrum, 100-300GHz, is well understood: vast swaths of underutilised
spectrum and the ability to transmit data at rates far beyond what is possible at lower frequencies. While much of the development in this range remains at the R&D stage, recent breakthroughs are already expanding the reach and speed of this new technology. With the potential to exceed 100Gbps
– over 500 times faster than current 5G networks – the move into the THz bands stands to accelerate a range of advanced applications. Tese range from phased- array radar and autonomous vehicles, to fixed wireless backhaul and ultra-high- capacity data centre links. Yet researchers continue to explore the most efficient ways to achieve such high data throughput with real-world hardware. As part of that pursuit, engineers in a
recent live demonstration successfully transmitted two independent, wideband signals, each on an orthogonal polarisation, through a single spatial link at 142GHz; see Figure 1. By combining both signals into one beam using a high-isolation, low-loss orthomode transducer (OMT), the system effectively doubled the throughput of a
point-to-point connection. A follow-up demonstration at 285GHz is already in development, with the potential to push data rates even higher. Te effort was led by Virginia Diodes
(VDI) and Keysight Technologies, with Micro Harmonics providing the enabling OMT. While the breakthrough hinges on polarisation multiplexing, it is the result of a much broader integration effort. It brings together ultra-wideband mixers, sharp image rejection filters, high-frequency amplifiers and tightly engineered passive components, all optimised for operation deep into mmWave and sub-THz bands.
At the edge of the spectrum One of the central engineering challenges in sub-THz communication is the limited availability of hardware and the underlying components required for it to operate reliably at these frequencies. VDI’s contribution focused on overcoming that barrier: upconverting extremely wideband signals (20-40GHz) to higher carrier frequencies using custom diode- based mixers, then amplifying and refining those signals through carefully tuned image rejection filters and gain stages, all optimised for linearity and minimal loss. Te objective was straightforward:
deliver clean, high-power, wideband signals at 142GHz and beyond that
12 July/August 2025
www.electronicsworld.co.uk
could be transmitted and received with precision. However, wide bandwidth alone was not the full story. In earlier demonstrations, the team had already shown that two independent links at 142GHz and 285GHz could operate in parallel, each moving large volumes of data over separate beams. Tat setup effectively doubled throughput by doubling the number of physical links. Te next step was to achieve the
same throughput using just one beam. Tat meant combining two wideband signals, each occupying 20GHz, into a single spatial path without interference, requiring clean separation between the signals throughout the entire transmission and reception process. Tis is where
Figure 2: OMT from Micro Harmonics
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