Microwave propagation guided by one dimensional array of strongly coupled split ring resonators

• Main Authors: Vanna Chrismas Silalahi, 樊聖誕
• Other Authors: Watson Kuo
• Format: Others
• Language: en_US
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/77051641295588939874

碩士 === 國立中興大學 === 物理學系所 === 105 === Abstract We experimentally study microwave transmission guided by one dimensional (1D) array of coupled double split ring resonators (DSRR) and complementary split ring resonators (CSRR). Dimer of double split ring resonators (DSRR) and complementary split ring resonator (CSRR) are used as the building blocks of the 1D system. DSRRs and CSRRs are respectively fabricated on the front- and back-sides of a printed circuit board by using standard photolithography. The resonator array is coupled to two microstrips at each end for S-parameter measurement. Results are compared with simulation using High Frequency Structural Simulator (HFSS). For changing the inter-resonator coupling strength, arrays composed of circular and rectangular resonators are made and compared. The sizes of circular and rectangular resonators are respectively 7.6mm and 6.9mm for providing the same resonance frequency of about 3 GHz, which were confirmed in transmission spectroscopy. For circular resonators with inter-resonator distance d=10 mm, the transmission amplitude in dB scale at resonance frequency decreases linearly with dimer number N from -22 dB to -56 dB respectively,for N=5 and 30. With the same d=10mm and dimer number N=10, a larger transmission amplitude (from -30 dB to -18.8 dB) and greater bandwidth (from 0.27 GHz to 0.34 GHz) are founded for rectangular case than circular case, probably due to stronger inter-resonator coupling. The transmission amplitude and bandwidth strongly depends on the inter-resonator coupling between a DSRR and a CSRR. We investigate how these transmission properties are affected by inter-resonator distance d and ring orientation, which is parameterized by an angle θ to the array direction. A smaller d yields a larger transmission amplitude and larger bandwidth but the difference is not significant when d<11 mm. On the other hand, experiment and simulations shows that the orientation has a much greater impact to the transmission: A larger transmission amplitude -7.9 dB and a greater bandwidth 0.25 GHz are achieved when the orientation of DSRR and CSRR are θ= 90° for both of experiment and simulation. The smallest transmission amplitude and bandwidth are respectively -29.7 dB and 0.17 GHz when CSRR is rotated to θ= 240° (or 300° ). Simulation shows an uncommon feature at θ= 240° where the transmission passband splits into two subbands. Our results demonstrate a tunable microwave waveguide by changing the orientation of ring resonators.