Thanks to growing interest in spectroscopy, imaging, and other applications, the terahertz (THz) band has been expanding. Designers find it challenging, however, to design antennas with good performance in terms of radiation efficiency and input impedance with optimal match to a typically low-power source. Recently, a dielectric semiconductor horn antenna etched on a high-permittivity and thick substrate was proposed by the following: Belen Andres-Garcia, Enrique Garcia-Muoz, and Daniel Segovia-Vargas from the University of Madrid; Sebastian Bauerschmidt, Stefan Malzer, Gottfried H. Dhler, and Sascha Preu from Germany's Max Planck Institute for the Science of Light; and Lijun Wang from China's Tsinghua University.
With this design, the researchers propose a new geometry for the design of antennas in the terahertz band. Based on a horn configuration, this structure is etched on a substrate and fed with a planar printed antenna. The semiconductor horn antenna is used to transmit electromagnetic radiation from 200 GHz to 3 THz. To increase system gain, it reduces energy distribution through the substrate by at least 8 dB in a 1:10 bandwidth. The latter is achieved with a broadband, log-spiral antenna. See "Gain Enhancement by Dielectric Horns in the Terahertz Band," IEEE Transactions On Antennas And Propagation, Sept. 2011, p. 3164.