High efficiency wireless communications using MIMO (multiple-input, multiple-output) demands high isolation between antennas. An increase in antenna isolation equates to an increase in available bandwidth. The use of newly-allocated spectrum in the 700 MHz band presents unique challenges to antenna designers who now must develop effective antennas that work across spectrum ranging from 700 MHz (possibly even lower in the future) to the upper ranges of the 2 GHz band.
SkyCross has been developing antennas to meet these challenges. Last week the company announced it and China Mobile Research Institute demonstrated a tunable MIMO antenna for use in multimode, multiband handsets in LTE deployments world-wide. The antenna covers 12 frequency bands between 700 MHz and 2700 MHz. It's the result of a memorandum of understanding reached between SkyCross and China Mobile Research in Sept. 2010 to jointly pursue compact MIMO antenna design and implementation for multimode, multiband, LTE handsets.
The final tunable, multimode, multiband MIMO antenna design was tested at China Mobile Research Institute's and TMC laboratories in Beijing. It satisfied China Mobile's performance requirements. Bill Huang, General Manager of China Mobile Research Institute, commented, "Our joint development effort with SkyCross has demonstrated that cost-effective, multimode, multiband antennas are technically achievable for global LTE handsets. We believe this demonstration will accelerate the development of universal handsets capable of roaming worldwide, as well as create the manufacturing volume to meet all operators' requirements."
Detailed technical information on how SkyCross antennas for MIMO work is available in the white paper Isolated Mode Antenna Technology for 4G. With future LTE deployment being considered on frequencies as low as 400 MHz, I wonder if this technology could be extended to provide compact, isolated antennas for LTE at these low UHF frequencies? If so, it could help broadcasters, who at some point may decide to push for a switch to a transmission system using MIMO for TV broadcasting.
EPFL Scientists Develop Single Antenna MIMO System
"Beamspace MIMO" technique permits a significant reduction in the number of physical antennas in a MIMO system.