Lighter, Cheaper Radio Wave Device Could Transform Telecommunications

Lighter, Cheaper Radio Wave Device Could Transform Telecommunications(utexas.edu)

73 points by shitehawk 11 years ago | 6 comments

aethertap 11 years ago |

I had no idea what a circulator was or what purpose it served. The wikipedia link has a good description of what it is, and the pdf link is a paper about how to achieve full duplex radio operation, and shows where the circulator fits into the picture.

1. https://en.wikipedia.org/wiki/Circulator

2. http://web.stanford.edu/~skatti/pubs/sigcomm13-fullduplex.pd...

_Adam 11 years ago |

My initial impression is that this is a very significant advance; enabling full-duplex on a single frequency band effectively doubles the communication bandwidth. But, I'm not sure if this translates to the real world.

Can any RF engineers comment on this?

Aloha 11 years ago | |

No. The circulator itself is not a new invention, this is just a new way of building them.

CamperBob2 11 years ago |

Not clear how this is different from any other Wheatstone bridge-like structure used for directional sensing at microwave frequencies. Lower loss, presumably? Active circulators by themselves aren't new ( https://www.google.com/?gws_rd=ssl#safe=off&q=wenzel+active+... ).

createacc123 11 years ago | |

This is not an active circulator, there are no amplifiers. It's a parametric-modulated circulator - the capacitance is modulated. Not a new concept in microwave engineering. Not very useful in real-life: the PR-heavy letter neglects to mention (1) the poor instantaneous bandwidth <0.5% (figure 4c), (2) the poor linearity / poor power handling: Vm and Vdc are few volts in high-Q environment, which translates into maximum power handling well below 0dBm (3) the high sensitivity to analog component variation (fig 4c again) - not something you want in mass-produced components operating at commercial/industrial temperature ranges.

They neglected to mention the power level they used to measure the S-parameters in the letter or the supplementary material. No self-respecting RF engineer would forget to mention power levels - it again hints at very poor linearity / poor power handling. Typical university "research".

vmarsy 11 years ago | |

the Nature article linked in the parent link probably has more information:

http://www.nature.com/nphys/journal/vaop/ncurrent/full/nphys...