The Matsunaga Lab at Ehime University developed a spiral antenna that can emit different polarized waves at three different frequencies.
It was exhibited at the 2012 Microwave Workshops & Exhibition (MWE 2012), which took place in late November 2012 in Yokohama, Japan.
The antenna was made by placing cross spiral-shaped passive elements around a cardboard antenna so that circularly-polarized waves and linearly-polarized waves can be shared at three different frequencies. Unlike traditional dual polarized antennas, it has a single-layer structure and requires only one port for power supply.
"Because it has a very simple structure, it can be easily commercialized," the Matsunaga Lab said. "Also, it can be mass-produced."
The antenna is expected to be used for compact devices that use multiple radio frequencies such as tablet computers and notebook computers.
Ehime University has been engaged in the development of a spiral antenna that enables to share circularly- and linearly-polarized waves at multiple frequencies and proposing antennas that do not require a phase shifter and have a simple structure. It announced the latest antenna in March 2012 at an academic conference organized by the Institute of Electronics, Information and Communication Engineers (IEICE).
At MWE 2012, the Matsunaga Lab showed the antenna being used at the frequencies for wireless tags, GPS, mobile phones, etc. For example, the exhibited antenna can emit 920MHz linearly-polarized waves, 1.575GHz circularly-polarized waves and 1.8GHz linearly-polarized waves. And the Matsunaga Lab explained the superiority of the antenna by showing its current distribution, return loss properties, etc.
The antenna has a structure in which loops and spirals are wound in a cross shape and is called "CSA (Cross Spiral Antenna)." The Matsunaga Lab has already started to consider commercializing the antenna with some manufacturers. For the future, it plans to reduce the size of the antenna while improving its dielectric materials, etc.