Optimization based design of a wideband near zero refractive index metasurface for gain improvement of planar antennas i
- PDF / 3,034,898 Bytes
- 16 Pages / 439.37 x 666.142 pts Page_size
- 18 Downloads / 194 Views
Optimization based design of a wideband near zero refractive index metasurface for gain improvement of planar antennas in the terahertz band Seyed Saeed Efazat1 · Raheleh Basiri1 · Shahrokh Jam1 Received: 19 July 2020 / Accepted: 20 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this paper, a broadband near-zero refractive index metasurface is designed in the terahertz band. The Random Hill Climbing optimization algorithm is utilized to propose the corresponding unit cell. The designed metasurface is employed as the superstrate of two planar microstrip wideband antennas resulting to increase the gains of antennas. The impedance and 3-dB gain bandwidths of loaded patch antenna are 46% and 36%, respectively while these parameters are 17% and 28.5% for printed dipole antenna in the presence of designed metasurface. Moreover, the maximum gain of loaded patch and printed dipole antennas are 9.1 dB and 11.74 dB, consequently. The provided results confirm that the proposed structures achieve higher maximum gain and wide 3-dB gain and impedance bandwidths with respect to similar reported antennas. In addition, at least 3 dB gain improvement is achieved in the presence of designed metasurface on the top of antennas. Keywords Antenna · Gain · Metasurface · Optimization · Terahertz · Wideband
1 Introduction Terahertz (THz) region is defined as the range of frequencies from 0.1 to 10 THz, which is categorized as an extremely large frequency band between microwave and infrared frequencies. Recently, the THz band has attracted researchers interest due to corresponding potentials in various applications such as radio-astronomy, THz imaging, remote sensing, THz radar, biosensors (Bowman et al. 2015), and space communication (Tonouchi 2007; Federici and Moeller 2010). Based on Shannons ideal communication theorem (Huang and Wang 2011), increasing bandwidth of communication channels leads to systems with higher data rate transferring (terabit-per-second). One of the most critical parts of THz communication systems is antenna. Therefore, high performance antennas are demanded for THz applications. Moreover, among various types of antennas, planer antennas with corresponding valuable benefits such as low cost,
* Raheleh Basiri [email protected] 1
Department of Electrical Engineering, Shiraz University of Technology, Shiraz, Iran
13
Vol.:(0123456789)
520
Page 2 of 16
S. S. Efazat et al.
low profile, low weight and easy fabrication are desirable. These antennas can be simply integrated to the lateral devices such as couplers, dividers and amplifiers. Therefore, they are good candidates for THz applications. In spite of the mentioned advantages, they suffer from some serious drawbacks including narrow bandwidth and low efficiency and gain. This is due to propagation of spurious surface waves in dielectric substrate and skin effect of metal in planer antennas at THz frequencies, which reduces the corresponding radiation efficiency and gain (Ghosh and Mitra 2017). Vario
Data Loading...
