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Improving confidence in parameters for emerging high frequency communications and electronic technologies

The project

The rollout of 5G networks and large-scale deployments of cellular Internet of Things (IoT) will lead to fundamental changes to our society, impacting not only consumer services but also industries embarking on digital transformations. Connected and autonomous vehicles are progressing rapidly and are expected to improve traffic flow, safety and convenience significantly. Space deployed radiometers are used for passive remote sensing of atmospheric constituents which are related to climate change and play a critical role in environmental protection.

All these applications require the use of the millimetre-wave and terahertz (THz) regions of the electromagnetic spectrum, and demand devices and integrated circuits operating at these high frequencies. However, the development of devices and systems to underpin these applications is currently hampered by the lack of traceability for electrical measurements at millimetre-wave and THz frequencies.

Completed EMPIR project Traceability for electrical measurements at millimetre-wave and terahertz frequencies for communications and electronics technologies (18SIB09, TEMMT) established traceability to the International System of Units (SI) for measuring S-parameters, power, and complex permittivity of dielectric materials, at terahertz frequencies. S-parameters, or scattering parameters, measure the loss and phase change for transmitted and reflected signals. Traceability and verification techniques were developed, contributions made to international standards bodies, and developments promoted to NMIs – to facilitate coordinated measurement capabilities. Exploiting this part of the spectrum results in improved product quality and end-user confidence in the communications and electronics industries, and competitive advantage for European economy.

Novel sensor

During the project the first bolometric sensor in Europe for D-band (110-170 GHz) power measurements was designed and constructed by the University of Birmingham in the UK. This sensor is described in the paper Design, fabrication, and characterization of a D-band bolometric power sensor - University of Birmingham.

At the core of the novel sensor is a small chip (10.4 mm ×5.65 mm) with a silicon substrate that heats up as it absorbs millimetre waves. This heat is transmitted to a platinum layer, which changes resistance in response, and this gives the equivalent DC signal. The sensor was characterised in a microcalorimeter during the project, demonstrating high power linearity and an effective efficiency of over 90 %.

NPL, the National Metrology Institute of the UK has since purchased two of these sensors with the aim of getting UKAS accreditation for the first measurement service for frequencies in this range.

New sensors based upon the same concept are being further developed in the European Partnership project RF key quantities for 6G development (23IND03, RF 4 6G).

Other project outputs

Other project outputs include:

• First of kind intercomparison of material measurements over three decades of frequency using five different measurement methods. The comparison was described in detail in EURAMET project 1514 Comparison on material parameter measurements in the THz spectral range with optical, resonant and VNA based setups, as well as in a paper entitled Interlaboratory Comparison of Dielectric Measurements From Microwave to Terahertz Frequencies Using VNA-Based and Optical-Based Methods.
• First of kind interlaboratory comparison in on-wafer measurements covering frequencies from 110 GHz to 1.1 THz. The comparison was reported in a paper entitled Interlaboratory Investigation of On-wafer S-parameter Measurements from 110 GHz to 1.1 THz
• New measurement capabilities at NMIs – for example new measurement systems are now operational at several European NMIs (i.e. LNE, NPL and PTB) to enable both dimensional and electrical measurements of coaxial components in the 1.35 mm line size
• Significant contribution to IEE standards: IEEE MTT/SCC P287, IEEE MTT/SCC P2822, IEEE MTT/SCC P1785
• 31 peer reviewed publications, 25 conferences, 3 one-day workshops as part of premier international conferences, 2 training courses

The work of this project will have a direct impact on the communications and electronics industries 5G communications, the IoT, radar sensors for connected and autonomous vehicles, space-borne radiometers for Earth monitoring, and security imaging. Improvement of measurement accuracy and establishment of measurement traceability will enable manufacturers to provide confidence in their measurements and specifications.

Project coordinator Xiaobang Shang from NPL said ‘

I was honoured to have the opportunity to lead this large-scale European metrology project, EMPIR TEMMT (2019 – 2022), involving 19 partners globally and a highly successful project despite setbacks due to COVID. As a result of this project, significant progress has been made in terms of establishing traceability for E-band (1.35 mm) coaxial connector measurements, waveguide S-parameter measurements to 1.5 THz, on-wafer S-parameter measurements to 1.1 THz, power measurements to 750 GHz, and material characterisations to 6 THz. Outputs of this project enable end-users to have confidence in measurement and specifications and to offer assured products through measurement traceability chains.’

This EMPIR project is co-funded by the European Union's Horizon 2020 research and innovation programme and the EMPIR Participating States.

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