Metamaterials-Based Antenna Packs High Effiency into Tiny Package

nist-antenna

A miniature antenna retains efficiency at a fraction of the size of standard antennas.

A collaborative research team with members hailing from the National Institute of Standards and Technology (NIST; Gaithersburg, MD), the University of Arizona (Tucson), and Boeing Research & Technology (Seattle) has produced an antenna that demonstrates efficiency and has properties comparable to those of standard antennas in a significantly smaller package. Such an antenna could be useful for microsensors and miniature devices requiring wireless connectivity.In order to operate efficiently, conventional antennas must measure at least half the size of the signal wavelength, according to NIST. Measuring 1/50th of a wavelength and capable of radiating as much as 95% of an input radio signal, the NIST antennas could be a game changer.This dramatic size reduction while maintaining efficiency is attributed to the inclusion of metamaterials, according to the researchers. Metamaterials are specially engineered materials that exhibit unusual properties typically not found in nature. In addition, the researchers speculate that the metamaterials could enable the antenna to communicate at any frequency."The purpose of an antenna is to launch energy into free space," says NIST engineer Christopher Holloway. "But the problem with antennas that are very small compared to the wavelength is that most of the signal just gets reflected back to the source. The metamaterial makes the antenna behave as if it were much larger than it really is, because the antenna structure stores energy and reradiates it."In the most-recent iteration of the antenna, the researchers employed a z-shaped strip of copper with an inductor in the center as the integral metamaterial. It was mounted to the back of a copper square on which a metal wire antenna was printed.Antenna innovations are cropping up lately, as researchers address industry needs for more-efficient, smaller devices capable of sending and receiving data or information. Read about a novel flexible antenna from the most-recent issue of MPMN.