Study of the Super Directive THz Photoconductivity Antenna
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Study of the Super Directive THz Photoconductivity Antenna Guizhen Lu1 · Ruiqi Zhao1 · Hongcheng Yin2 · Zhihe Xiao2 · Jing Zhang2 Received: 27 February 2020 / Accepted: 13 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The photoconductivity antenna is a promising technology to generate THz wave. However, the technology is problematic in THz low antenna gain. The improvement of efficiency and directive is very important to the photoconductivity antenna. Here, a super directivity THz photoconductivity antenna (PCA) is proposed. The antenna uses the dielectric resonator to enhance the directivity which yields the super directivity in radiation. The eigen mode analysis is performed to the super directivity antenna, which is used to help design the antenna and understand the mechanism for the super directivity. The spherical cap is used as the dielectric resonate antenna (DRA), and the relationship between the radius of sphere and the height of cap and super directivity is surveyed. The dielectric cap height and sphere radius are found both playing an important role in enhancing the directivity of the antenna. To validate the proposed design, a THz photoconductivity antenna is designed. The simulations are performed using FDTD and FEM method. Both results show that the designed THz antenna has the super directivity value above 9.0 at 2.0 THz. Keywords PCA · DRA · Super directive · Thz generation · Antenna gain
Introduction The study on THz technology is a hot topic in the microwave and photonic research area. The frequency spectrum of THz is between the microwave and the far infrared band. Unlike the microwave and photonic band, there are no efficient technologies to generate and detect the THz wave at present [1]. Among the generation and detection of THz wave, the photoconductivity antenna (PCA) is a promising technology because of its economy and compactness. The basic component of PCA is a metal dipole that is DC biased. The optical pulse is incident on the antenna gap to produce the carrier in the semiconductor, in which the carrier forms a current on dipole in the action of DC bias voltage. The antenna gain is the product of the antenna efficiency and radiation directive. In order to enhance the antenna gain, it is necessary to enhance the efficiency and radiation directive. One of the shortcomings of photoconductive antennas in terahertz * Guizhen Lu [email protected] 1
College of Electronic Engineering, Communication University of China, Beijing 100024, China
Beijing Institutes of Environmental Properties, Beijing 100039, China
2
(THz) generation is low antenna gain. In order to enhance the PCA gain, there are many researches to improve the PCA efficiency and directive. The efficiency of a THz system strongly depends upon the electric field strength [2][3]. In order to increase the incident optical intensity, the grating structure is used to improve the matching between the semiconductor and free space [4].The further improvement is to make use of t
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