In the last years, the Terahertz band has achieved great importance due to its multiple applications in different fields. These applications may go from medicine, to defense and security. Additionally, its short wavelength allows to transmit large amount of data in a short period of time. Developing the Terahertz technology could lead to an improvement in the existing applications and to overcome different problems that actual technology presents. For example, harmful X-Ray scanners could be replaced by Terahertz technology avoiding that it affects negatively to the human health. Spectroscopies with higher resolution can also be performed thanks to the Terahertz waves. However, this band, sometimes called as frequency gap, presents some limitations related to the radiated power. Although big efforts have been made within the last decade to close the gap, obtaining high power in the THz band is still challenging. There exist two different alternatives so as to generate THz power. By using electronics, where higher power can be achieved or through optoelectronics using photomixing technics. This project is focused in the later alternative, where getting higher powers is more challenging. This work is part of a broader interdisciplinary project that involves experts from different fields, combining the expertise on antenna design at the Signal and Communications Theory Department at Universidad Carlos III de Madrid with the experience at the Max Planck Institute for the Science of light (Erlangen, Germany) on optoelectronic THz emitters. The specific aim of the thesis is to study different ways of enhancing the radiated THz power through simulation and through experimental results. Three different approaches are done in order to achieve the desired results. Firstly, a 2D-array of TSA antennas is intended. When constructing a 2D-array with end-fire antennas, the power will be increased due to the contribution of all antennas that compose the array. However, before constructing it, it is required to perfectly understand how these antennas behave under the circumstances that are required for designing an array. As second alternative, simple antenna emitters are used. These antennas are dipoles or spirals antennas connected to a photomixer device able to generate Terahertz power. The main task is to optimize all the designed structure so as to obtain a symmetric radiation pattern, and calculate its corresponding equivalent circuit. Lastly, some experimental measurements are done. These results are attained with dielectric horn antennas measured in the laboratory of the Max Plank Institute for the Science of Light in Erlangen. The efficiency of different antennas should be studied so as to know how the improvement introduced by the dielectric horn etched is. In these different ways, enhancement in the Terahertz power is achieved broadening the possible applications of this technology. ______________________________________________________________________________________________________________________________