By Melanie Mingas
NTT DOCOMO has developed an antenna system capable of creating a high-frequency mobile communication cell when a small piece of plastic is placed on top of a dielectric waveguide.
Tested using roughly one cubic centimetre of plastic, solid cube serves as an antenna by creating a “leak” from the cable to propagate signals up to several tens of metres, according to DOCOMO.
It said it successfully tested the system with an ultra-high-frequency 60 GHz radio signal, similar to those expected to be used in future 6G networks.
DOCOMO explained that its Drop-n-Prop Antenna, takes advantage of the physical phenomenon of radio waves propagating from the contact point created by “dropping” a small piece of plastic on top of a dielectric waveguide carrying the signal.
The result is that instant mobile environments can now be created in indoor areas not reachable with highly directional high-frequency signals propagated by outdoor base stations. Furthermore, the solution is low cost and, because signals are only propagated to required areas, wasteful usage of power is eliminated.
The company explained: “In the trial, DOCOMO constructed a communication area by running a rod-shaped dielectric waveguide made of polytetrafluoroethylene into an indoor area that was inaccessible to external mobile signals. The waveguide was embedded in a length of polystyrene-foam board with one side barely exposed to allow contact with antennas. Multiple communication cells were created simultaneously by placing antennas along various parts of the waveguide. Signal coverage and direction were controlled by changing the material, shape and positioning of the antennas.”
It is difficult for millimetre waves to reach devices not in a base station’s direct line of sight, or if the signals are blocked by surrounding obstacles, including walls. DOCOMO’s low-cost antenna system overcomes such hurdles as it only requires a rod-shaped dielectric waveguide to be run into an area and then embedded in the floors, walls, ceilings, furniture or work surfaces. Communication areas can be constructed easily and unobtrusively in offices, factories, etc. and reconfigured quickly and flexibly just by moving the antenna(s) as required.
System verification – using 28 GHz 5G radio signals – will take place from April.
