Smrity Dwivedi,  Effect on Bandwidth of Using Double Substrates Based Metamaterial Planar Antenna.   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    June 2017, vol. 126(6). 738 - 742
    [viewed 23 October 2019]. Available from: https://publications.waset.org/pdf/10007628.