AN IMPROVED ZEROTH ORDER RESONATOR USING LEFT HANDED METAMATERIAL
Keywords:Composite right left handed transmission line, Interdigital capacitor, Left handed metamaterial, Zeroth order resonator
In this paper an improved version of zeroth order resonator (ZOR) using Left Handed Metamaterial (LHM) is reported, and its performance is compared with the earlier published ZOR. The resonator is designed based on microstrip technology using composite right left handed transmission line (CRLH TL) approach. The conventional ZOR is designed based on the CRLH TL along with two coupling slots at the input and output ports, whereas the proposed design of ZOR is based on
coupling capacitors. Use of coupling capacitor in place of coupling slot improves resonance characteristic of ZOR in terms of return loss and insertion loss and also increases the operational bandwidth. The measured resonant frequency, return loss, insertion loss and fraction bandwidth of the proposed 1.5- unit cell ZOR are 1.5 GHz, -26.31 dB, -0.42 dB and 20.66% respectively, whereas for the conventional 1.5-unit cell ZOR these measured parameters are 1.8 GHz, -6.63 dB, -9.09 dB and 0.77% respectively. The frequency parameter and performance of the resonators are evaluated by full-wave electromagnetic simulator, IE3D, based on method of moments (MoM) and all these results are verified by measurements.
(LHMs) in waveguide configurations,” J. App. Phys., vol. 90, no. 11, pp. 5483-5486, Dec. 2001.
 C. R. Simovski, P. A. Belov, and H. Sailing, “Backward wave region and negative material parameters of a structure
formed by lattices of wires and split-ring resonators,” IEEE Trans. Antennas Propagat., vol. 51, pp. 2582–2591, Oct.
 A. Lai, C. Caloz, and T. Itoh, “Composite right/left-handed transmission line metamaterials,” IEEE Microwave
Magazine, vol. 5, no. 3, pp. 34-50, Sep. 2004.
 Casares-Miranda, F. P., C. Camacho Peñalosa, and C. Caloz, “High-gain active composite right/left-handed leakywave antenna,” IEEE Trans. Antennas Propag., vol. 54, no. 8, pp. 2292-2300, Aug. 2006.
 A. Lai, K. M. K. H. Leong, and T. Itoh, “Infinite wavelength resonant antennas with monopole radiation pattern
based on periodic structures,” IEEE Trans. Antennas Propag., vol. 55, no. 3, pp. 868–875, Mar. 2007.
 R. Marque, F. Martin and M. Sorolla, Metamaterials with Negative Parameters: Theory, Design, and Microwave
Applications, 1st ed.,John Wiley & Sons, Inc., Hoboken, NJ, 2008.
 C. Caloz and T. Itoh, Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications, 2
ed., Wiley and IEEE Press, Hoboken, NJ, Dec. 2005.
 Taehee Jang, Jaehyurk Choi and Sungjoon Lim, “Compact Coplanar Waveguide (CPW)-Fed Zeroth-Order Resonant
Antennas With Extended Bandwidth and High Efficiency on Vialess Single Layer,” IEEE Trans. on Antennas and
Propag., vol. 59, no. 2, pp. 363-372, Feb. 2011.
 D. M. Pozar, Microwave Engineering, 2nd ed., Toronto: Wiley, 1998.