Reflectarray Antennas

8Terahertz, Infrared, and Optical Reflectarray Antennas

Electromagnetic waves cover a wide frequency spectrum, including microwaves and optics. The wave behavior at both microwave and optical frequencies follow Maxwell’s equations; hence many microwave concepts have been extended to optics, and in turn a lot of optical designs have been translated to microwave frequencies. For example, the invention of optical fiber [1], a kind of dielectric waveguide, greatly propelled the development of optical communications and the Internet. In addition, resonant optical antennas [2], are recently being studied that could contribute to the improvement of light emitters in the future.

In this chapter, we present some of the latest progress in terahertz, infrared, and optical reflectarray antennas. Most reflectarray antenna research in the recent years has been in the microwave and sub‐millimeter range [3], and while microwave concepts can generally be extended to higher frequencies, several factors come into play that complicate the antenna design. In this chapter, we will first study some basic material characteristics and design challenges, and then review several THz, infrared, and optical reflectarray antennas that have been developed over the years.

8.1 Above Microwave Frequencies

The region of frequency spectrum between microwave frequencies and visible light consists of terahertz (THz) and infrared bands, as shown in Figure 8.1. While certain applications such as far‐infrared spectroscopy ...