V. Kesornpatumanun and  P. Boonek and  W. Silabut and  N. Homsup and  W. Kuhirun,  High Directivity and Gain Enhancement for Small Planar Dipole Antenna at 11 GHz Using Symmetrical Pyramidal Block Based On Epsilon Negative Medium.   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    July 2014, vol. 89(5). 817 - 820
    [viewed 18 October 2019]. Available from: https://publications.waset.org/pdf/9998889.