Continued from Performance of Kyocera's Antenna Does Not Lower Even on Metal Surface (1)

The characteristic realized by using the meta-material this time is that its reflectance property for electromagnetic waves is "magnetic." Such a meta-material is called "artificial magnetic conductor (AMC)." The name Amcenna is a word created by combining "AMC" and "antenna."

When the reflectance property is magnetic, the phase of electromagnetic wave is not inverted at the time of reflection, Kyocera said. In general, when an electromagnetic wave is reflected from metal surface, there is almost no transmitted wave, and the electric field intensity on the metal surface is almost zero, inverting the phase of the wave at the time of reflection. It is so-called "reflection at a fixed end."

In this case, the intensity of electromagnetic wave near the metal surface is drastically lowered because the incident wave almost offsets the reflected wave. This is the reason why the performance of commonly-used antennas is drastically lowered on metal surface.

On the other hand, with an AMC, the reflection of electromagnetic wave is a "free-end" type, meaning that the phase of reflected wave is not inverted, Kyocera said. As a result, the incident wave does not offset the reflected wave, and the performance of antenna does not lower.

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In fact, such AMCs have been known for long, and, at least, a thesis was written about them in 2005. Antenna manufacturers including Kyocera have already developed some antennas that use an AMC as a substrate, etc. However, it had been difficult to commercialize them.

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