Electromagnetic radiation of carbon nanotube array in microwave frequencies

We report electromagnetic radiation experiments of nanotube arrays, using a microwave as the excitation source, which probe the electromagnetic radiation characteristics of nanotube arrays. We determine the shortest length of a nanotube to radiate a special frequency. Our results show that nanotube arrays can radiate electromagnetic waves as long as their frequencies are higher than the specified frequency. Moreover, our results also show that the nanotube arrays have higher radiation efficiency.