Investigating the upper bound of high-frequency electromagnetic waves on unshielded twisted copper pairs

Abstract

This paper explores the behaviour of the ubiquitous twisted pairs at high frequencies and wideband excitation of twisted pairs up to 12 GHz. Higher carrier frequencies on twisted pairs can enable the data rates required by the future communication networks; hence, the existing copper infrastructure can be utilised on the last mile complementing the fibre networks. In this paper, we show a fundamental limit on the operating frequency of twisted pairs beyond which twisted pairs start to radiate and behave like an antenna. To validate our theoretical derivations through measurements, we designed a microstrip balun to excite the differential mode on the twisted pairs. At the end, we demonstrate that the standard twisted pairs used in the UK can be used up to 5 GHz carrier frequency without any radiation effect and this upper-bound can be moved to higher frequencies by decreasing the twist lengths.

Design of filtering cable with defected conductor layer

“…The comparative characterization of the proposed filtering cables with various existing cables and filtering techniques is presented in Table 1 . Shielding cables 16 can shield EMI, coaxial cables 17 can achieve high bandwidth communication over relatively long lines, and twisted wire pair 18 can eliminate common-mode interference. However, none of them have filtering capabilities, while filtering cables are capable of filtering EMI.…”

“…The most important feature is the distributed filtering function along the length of the cable 14 Shielding cable Cables with a shielding layer can achieve electromagnetic shielding performance, but they do not have a filtering function 15 Coaxial cable Invented by Oliver Heaviside, coaxial cables provide stable impedance and phase in a broad frequency band and have good signal integrity, but they do not have a filtering function 16 Twisted-wire pair A pair of mutually insulated wires is twisted together to transfer differential mode signals and eliminate common mode interference 17 Flexible microstrip-filtered transmission line The flexible microstrip-filtered transmission line is made of FPCB, which is very thin and light, and has filtering capabilities. It can replace traditional coaxial lines and be conveniently used for mobile or flexible communication terminals 18 Suspension filter circuit The filtering function is achieved by adding capacitors and wires to the silicon rubber pad, which can be installed in the connectors. However, the filtering performance is weak and the reliability is not very high 19 Filtering connector Filtering connectors can be achieved by adding capacitors and inductors inside the connector, which is a type of lumped filter rather than a distributed filter 20 Ferrite magnetic ring Passing the cable through the magnetic ring can suppress high frequency interference on the cable.…”

“…In order to improve EMC, shielded cables and lumped filters are commonly employed for interconnections within and between equipment. Existing particular cables and filters technologies include shielding 16 , coaxial geometry for achieving electromagnetic shielding with stable impedance and phase 17 , twisted-pair geometry for reducing common-mode interference 18 , flexible microstrip filter transmission line with defected ground structure (DGS) 19 , suspension filter circuit 20 , filtering connector 21 , magnetic material filtering 22 , lumped electronic components filters 23 , waveguide filters 24 , ceramic filters 25 , 26 , DGS filters 27 , microstrip filters 28 , 29 , and various types of filters 30 , 31 , etc. However, it is worth noting that, currently there is a lack of distributed filtering functionality along the length of the cable.…”

A cryogenic on-chip microwave pulse generator for large-scale superconducting quantum computing

“…Remarkably, benefiting from the relatively small bandwidth of the digital drive signal, twisted pairs of wires can be used to deliver the step drive signal from room temperature to cryogenic temperature to actuate the microwave emission. Even though the flux drive signal is distorted by the limited bandwidth of the twisted pairs, well-controlled microwave pulses can still be effectively generated, but with a lower output power, which is typically about 0.07 times that of the coaxial cables and can be improved by optimizing the design of the twisted pairs 30 . Detailed results can be found in Supplementary Note 4 .…”

Filter cable design with defected conductor transmission structures

“…lectrical cables 1 , as current-carrying conductors, act as the coupling path of undesirable electromagnetic interference (EMI) 2 , which can potentially impact the proper operation of electronic devices. According to the basic framework of any electromagnetic compatibility (EMC) design 3 , electrical cables not only conduct electromagnetic interference (EMI), leading to symptoms of conducted emissions (CE) and conducted susceptibility (CS) 4,5 , but also radiate electromagnetic energy 6 , causing issues with radiated emissions (RE) and radiated susceptibility (RS) 7,8 . Moreover, with the rapid advancements in technology, including the smart grid, next-generation communication technologies 9 , the Internet of Things (IoT) 10 , unmanned systems, and artificial intelligence, the development and application of critical infrastructure and advanced intelligent equipment and systems have become pivotal factors in achieving reliable and secure operations.…”