ANTENNAS with the flexibility to reconfigure their radiation patterns can be useful in wireless communications systems for spectrum reuse and for mitigating interference. Researchers Shahrzad Jalali Mazlouman, Xing Jie Jiang, Carlo Menon, and Rodney Vaughan with the School of Engineering Science at Simon Fraser University (Burnaby, BC, Canada) and Alireza Mahanfar with Microsoft (Redmond, WA) designed a bendable, frequency-reconfigurable monopole antenna by embedding a liquid-metal alloy (Galinstan) microchannel in a polydimethylsiloxane (PDMS) substrate. The researchers discovered that the resonant frequency of the liquid-metal wire antenna could be tuned by stretching the substrate, thereby altering the effective length of the antenna. The stretchable patch antenna could be strained by as much as 300% so that the antenna could be tuned from 1.3 to 3.0 GHz. A maximum radiation effi ciency of 80% was measured for the antenna.

The antenna consists of two 40 x 150 mm2 TC5005 silcone elastomer layers enveloping a rectangular patch formed by a Galinstan reservoir measuring 31 x 31 x 0.5 mm3. The ground plane is a square copper metal piece with a slot in the middle used as a feed. The ground plane measures 300 x 300 mm2.

The fabricated prototype antenna demonstrated good impedance matching over a wide range of resonant frequencies. Even when the antenna patch is stretched and the patch conductor is at its thinnest, the antenna provides good efficiency, indicating the potential of this design technique for multiple wireless communications applications. See "A Reconfigurable Patch Antenna Using Liquid Metal Embedded in a Silicone Substrate," IEEE Transactions on Antennas and Propagation, Vol. 59, No. 12, December 2011, p. 4406.