TY - GEN
T1 - Design of efficient Terahertz antennas
T2 - 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010
AU - Choi, Sangjo
AU - Sarabandi, Kamal
PY - 2010
Y1 - 2010
N2 - Carbon nanotube (CNT) has been introduced as a new material for antenna radiators and transmission lines in Terahertz frequencies. The intrinsic conductivity of single-wall carbon nanotube (SWNT) is rather higher than that of copper in DC, however due to its very small radius (on the orders of a few nanometers), its resistance per unit length is very high [1]. These properties limit its utilization for RF applications, such as electrical interconnects and radiating elements. Thus, to reduce the high resistance of SWNT, the bundled structure of CNTs is suggested [2]. In laboratory measurements up to 50 GHz, it was shown that the resistance of bundled CNT is simply equal to component value of discrete circuit element of SWNT divided by its number density [CNTs/μm] [2]. The current fabrication technology produces a number density of 10 [CNTs/μm] in well-aligned arrays [3]. The discrete circuit model of SWNT in theory [4], the series kinetic inductance Lk of 16nH/μm and the resistance of 6.5kΩ/μm are employed in this paper. In addition, the fact that the quality factor of this RL series circuit of SWNT is approximately 100 at frequencies higher than 6.5 THz invokes the application of SWNTs as antenna radiators at terahertz frequencies. This high Q factor at terahertz frequencies is preserved in the bundled structure because SWNTs in the bundle are connected in parallel. Also, one dimensional transport of electrons along SWNT indicates that the concept of skin depth for the conventional conductor is not applicable, so the high conductivity of SWNT is obtained even though the thickness of bundled SWNT is very small compared to the wavelength. On the other hand, the surface resistivity of general conductors increases with frequency due to skin depth effect. Thus, it is expected that the performance of CNT antenna should surpass that of metallic antennas in terms of radiation efficiency at a particular frequency in Terahertz region. To apply high frequency properties of metal (the thin gold film in this paper), the Drude model is utilized [5]. In this paper, an anisotropic resistive sheet model to represent bundled CNTs electromagnetically is presented. Then, a numerical simulation using method of moments (MoM) is developed to calculate radiation efficiencies of resonant strip antennas made up of bundled CNT and thin gold film. The radiation efficiencies are compared as a function of frequencies and number density of bundled CNT to find a crossover frequency where CNT antenna outperforms the thin gold film antenna.
AB - Carbon nanotube (CNT) has been introduced as a new material for antenna radiators and transmission lines in Terahertz frequencies. The intrinsic conductivity of single-wall carbon nanotube (SWNT) is rather higher than that of copper in DC, however due to its very small radius (on the orders of a few nanometers), its resistance per unit length is very high [1]. These properties limit its utilization for RF applications, such as electrical interconnects and radiating elements. Thus, to reduce the high resistance of SWNT, the bundled structure of CNTs is suggested [2]. In laboratory measurements up to 50 GHz, it was shown that the resistance of bundled CNT is simply equal to component value of discrete circuit element of SWNT divided by its number density [CNTs/μm] [2]. The current fabrication technology produces a number density of 10 [CNTs/μm] in well-aligned arrays [3]. The discrete circuit model of SWNT in theory [4], the series kinetic inductance Lk of 16nH/μm and the resistance of 6.5kΩ/μm are employed in this paper. In addition, the fact that the quality factor of this RL series circuit of SWNT is approximately 100 at frequencies higher than 6.5 THz invokes the application of SWNTs as antenna radiators at terahertz frequencies. This high Q factor at terahertz frequencies is preserved in the bundled structure because SWNTs in the bundle are connected in parallel. Also, one dimensional transport of electrons along SWNT indicates that the concept of skin depth for the conventional conductor is not applicable, so the high conductivity of SWNT is obtained even though the thickness of bundled SWNT is very small compared to the wavelength. On the other hand, the surface resistivity of general conductors increases with frequency due to skin depth effect. Thus, it is expected that the performance of CNT antenna should surpass that of metallic antennas in terms of radiation efficiency at a particular frequency in Terahertz region. To apply high frequency properties of metal (the thin gold film in this paper), the Drude model is utilized [5]. In this paper, an anisotropic resistive sheet model to represent bundled CNTs electromagnetically is presented. Then, a numerical simulation using method of moments (MoM) is developed to calculate radiation efficiencies of resonant strip antennas made up of bundled CNT and thin gold film. The radiation efficiencies are compared as a function of frequencies and number density of bundled CNT to find a crossover frequency where CNT antenna outperforms the thin gold film antenna.
UR - https://www.scopus.com/pages/publications/78349261977
U2 - 10.1109/APS.2010.5560976
DO - 10.1109/APS.2010.5560976
M3 - Conference contribution
AN - SCOPUS:78349261977
SN - 9781424449682
T3 - 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010
BT - 2010 IEEE International Symposium on Antennas and Propagation and CNC-USNC/URSI Radio Science Meeting - Leading the Wave, AP-S/URSI 2010
Y2 - 11 July 2010 through 17 July 2010
ER -