Terahertz (THz) technology has emerged as a potential candidate for 5G and 6G communication. This is due to its prominent characteristics, such as ultra-high data transfer rates and large bandwidth. However, there are many drawbacks that impede the use of this technology, especially the conception and the design of THz sources. Photoconductive antennas (PCAs) are considered as the best candidate that allows the conception of ultrafast wireless communication systems. In the present work, we investigate and analyze two theoretical models: analytical and that based on equivalent circuit, which are used to characterize the generated photocurrent and the radiated THz pulse in the PCA. Besides, we discuss each model principle to identify the most convenient situation for applying it efficiently and correctly. Furthermore, we investigate the PCA parameters effect on the THz radiation for both: the photoconductive material and the exciting femtosecond laser. Simulation results allow the well perception of the physical interpretation for the radiation mechanism in each model, which leads to realize the consequence of misapplying the convenient model for the design, which is still the case of recent works. Moreover, the concepted PCA allows to have a wide bandwidth, that facilitates the realization of future wireless communication systems.