Carbon nanotubes (CNTs) are very interesting material for nanoelectronics for their unusual mechanical and electrical properties. They can be either metallic or semiconducting, depending on their geometry, and either single walled (SWCNT) or multiwalled (MWCNT). CNTs have been investigated for a wide array of applications including the possibility of building novel antennas in the nanometer scale. Many studies have been carried out to solve the problems associated with the CNT antennas. These studies don’t give an adequate solution because of the limitations in the adopted numerical analysis methods such as method of moments (MoM) and the inefficient assumption concerning the conductivity of CNT materials. This thesis investigates theoretically the characteristics of various terahertz antenna configurations formed by metallic CNT materials after modeling its conductivity accurately. The frequency dependent complex conductivity of the CNT material is taken into account in the investigation of these advanced antennas. The concept of effective conductivity is introduced for both SWCNT and MWCNT to make them in analogy with conventional antennas made of bulk metal wires. This is useful to apply Maxwell's equations simply to predict the electromagnetic properties of the CNT antennas.Quantitative predictions of the performance of CNT antenna dipoles, including input impedance, reflection coefficient, gain, and efficiency, are presented as a function of frequency. Simulation results are presented for SWCNT dipole. The results are extended to MWCNT and rectangular bundle CNT-based dipoles to address the effect of number of shells and number of tubes on antenna radiation pattern, respectively. All main properties are enhanced, one of these is the gain which is increased by factor of 15 and 100 for MWCNT and BCNT, respectively. The effect of using metal feeding contact with CNT antenna is examined and the results lead to the proposal of adopting CNT transmission line for feeding the CNT antenna. Simulation is carried further to predict the performance characteristics of square loop, circular loop, and helical antennas. All antenna configurations are simulated using computer simulation technology (CST) microwave studio (MWs) software package which is based on finite integration technique (FIT) instead of MoM. The results indicate that impedance matching is a serious problem in CNT antennas which can be relaxed using loop or helical configurations.