Trend: 60GHz band beckons

More than 150 years ago, James Maxwell wrote his famous equations (see below), and 30 years later, in 1895, physicist J.C. Bose channeled 60GHz signals in his laboratory (you can still see the equipment he used, including a Victorian polarizer, at the Royal Institution in London). Why this walk down memory lane? Because with the no-end-in-sight stalemate in which UWB has been mired, inquiring minds are beginning to take a serious look at 60GHz.

Several companies are already working in the space, including Sarasota, Florida-based xGtechnology and Sunnyvale, California-based SiBeam (the latter, though, is reluctant to be specific about what precisely it is developing, saying only that it is working on Gigabit wireless). The Berkeley Wireless Research Centre is developing CMOS chips for 60GHz. The IEEE has set up a task group, the 802.15.3c, to create a PHY standard for the frequency. The FCC has allocated a license-exempt band at the 57-to-64GHz band, sufficient for 2 Gbps throughput.

There are advantages to operating in the 60GHz band, such as reaching Gigabit speeds, but there are limitations as well, chief among them having to do with the propagation of electromagnetic radiation. Operating in 60GHz would be similar to operating with infra-red, requiring line-of-sight propagation. UWB, on the other hand, would offer a non-line-of-sight Gigabit propagation. If UWB finally fulfills its promise, 60GHz would be relegated to a supporting, "fast IRDA" role. But if UWB does not take off, and if 802.11n stays at about 500 Mbps in the existing 2.4Ghz and 5GHz, then 60GHz, with all its limitations, may become truly attractive.

For more on 60GHz activities:
- see Peter Judge's Techworld discussion
- the websites of xGtechnology | SiBeam

Background: Maxwell's equations represent an elegant and concise way to state the fundamentals of electricity and magnetism. The equations consist of a set of four fundamental equations which govern the behavior of electric and magnetic fields. They were written in complete form by the physicist James Clark Maxwell (1831-79), who also added the term displacement current to the final equation (although steady-state forms were already known).

For time-varying fields, the differential form of these equations in cgs is:



Where:  is the divergence; is the curl;  is the constant pi; E is the electric field; B is the magnetic field;  is the charge density; c is the speed of light; and J is the vector current density.