Calculating Millimeter-Wave Modes of Copper Twisted-Pair Cables Using Transformation Optics

Ali Mohajer Hejazi,Vincent Ginis,Gert-Jan Stockman,Werner Coomans,Yannick Lefevre

doi:10.1109/access.2021.3070192

Ali Mohajer Hejazi, Vincent Ginis + Show 3 more

Open Access

https://doi.org/10.1109/access.2021.3070192

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Abstract

Recent research has indicated considerable potential for millimeter-waves in copper access, with data-rate estimations up to 1 Terabit per second for a reach of 100 m. This line of research exploits millimeter-waves and their corresponding higher-order propagation modes inside the twisted pair cable binder. Unlike the conventionally used transmission-line mode (currents through copper wires), the approach relies on the copper and plastics present in these cables to form a low-loss waveguide. Here, we take a closer look at the potential of millimeter-wave propagation in twisted pair cables by refining the idealized assumptions, used by Cioffi et al. , and identifying the limiting factors. To this end, we introduce the concept of transformation optics as an efficient method of calculating the propagating modes on a twisted pair. Leveraging this technique allows us to calculate modal propagation using realistic material parameters, exposing an important trade-off between loss and confinement. Our modeling results yield achievable data rates that are orders of magnitude lower than those achieved under idealized assumptions. According to our results, 1 Terabit per second can be achieved up to a distance of about 10 m over a twisted-pair with a plastic sheath.

Highlights

Over the last three decades, telecommunication providers have largely succeeded in delivering broadband services in line with the increasing demand for bandwidth by leveraging a hybrid fiber-copper network
In this work we demonstrated that transformation optics is an efficient method to calculate propagation properties for twisted pairs
This method was leveraged to calculate the modes on a twisted pair with realistic loss assumptions and we observed a clear trade-off between confinement and loss

Summary

INTRODUCTION

Over the last three decades, telecommunication providers have largely succeeded in delivering broadband services in line with the increasing demand for bandwidth by leveraging a hybrid fiber-copper network. As frequency increases, the modes profiles become more closely concentrated to the metal and dielectric, leading to stronger interaction between these lossy materials This leads to higher losses, as seen on the bottom curves of Fig. 4. The plot shows that for higher frequencies, the mode profiles become more concentrated around the twisted pair This leads to an important conclusion of this work that there is a fundamental trade-off between the confinement of the modes and the losses they experience during propagation. The damping is large for all modes (Fig. 6 bottom) From these simulations, it is clear that, the plastic sheath and metal shield improve the confinement of the waves, overall, the total loss in the system has worsened (especially below 200 GHz) due to the increased exposure to the lossy dielectric and metal materials. This explains the slightly decreasing trend in damping for these modes

CAPACITY CALCULATIONS

CONCLUSION