1. Wu, B., Y. Ji, and G. Fang, "Analysis of GPR UWB half-ellipse antennas with different heights of backed cavity above ground," IEEE Antennas and Wireless Propagation Letters, Vol. 9, 130-133, 2010. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=5424004.
doi:10.1109/LAWP.2010.2044475
2. Wang, J., Y. Su, C. Huang, M. Lu, and Y. Li, "Design of bow-tie antenna with high radiating efficiency for impulse GPR," 2012 IEEE International Geoscience and Remote Sensing Symposium, 594-597, Jul. 2012. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6351524.
3. Lestari, A. A., E. Bharata, A. B. Suksmono, A. Kurniawan, A. G. Yarovoy, and L. P. Ligthart, "A modified bow-tie antenna for improved pulse radiation," IEEE Transactions on Antennas and Propagation, Vol. 58, No. 7, 2184-2192, Jul. 2010. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=5453013.
doi:10.1109/TAP.2010.2048853
4. Lestari, A., A. Yarovoy, and L. Ligthart, "RC-loaded bow-tie antenna for improved pulse radiation," IEEE Transactions on Antennas and Propagation, Vol. 52, No. 10, 2555-2563, Oct. 2004. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1341609.
doi:10.1109/TAP.2004.834444
5. Uduwawala, D., M. Norgren, P. Fuks, and A. Gunawardena, "A deep parametric study of resistor-loaded bow-tie antennas for ground-penetrating radar applications using FDTD," IEEE Transactions on Geoscience and Remote Sensing, Vol. 42, No. 4, 732-742, Apr. 2004. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1288368.
doi:10.1109/TGRS.2003.819442
6. Kim, K. and W. Scott, "Design of a resistively loaded Vee dipole for ultrawide-band ground-penetrating radar applications," IEEE Transactions on Antennas and Propagation, Vol. 53, No. 8, 2525-2532, Aug. 2005. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1492596.
doi:10.1109/TAP.2005.852320
7. Yang, H. and K. Kim, "Ultra-wideband impedance matching technique for resistively loaded Vee dipole antenna," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 11, 5788-5792, Nov. 2013. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6573326.
doi:10.1109/TAP.2013.2275981
8. Thaysen, J., "A logarithmic spiral antenna for 0.4 to 3.8 GHz," Applied Microwave and Wireless, Vol. 13, No. 2, 32-45, 2001.
9. Kock, W., "Metal-lens antennas," Proceedings of the IRE, Vol. 34, No. 11, 828-836, Nov. 1946. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1696976.
doi:10.1109/JRPROC.1946.232264
10. Pozar, D., "Flat lens antenna concept using aperture coupled microstrip patches," Electronics Letters, Vol. 32, No. 23, 2109, 1996. [Online]. Available: http://digital-library.theiet.org/content/journals/10.1049/el19961451.
doi:10.1049/el:19961451
11. Alù, A., M. G. Silveirinha, A. Salandrino, and N. Engheta, "Epsilon-near-zero metamaterials and electromagnetic sources: Tailoring the radiation phase pattern," Physical Review B, Vol. 75, No. 15, 155410, Apr. 2007. [Online]. Available: http://link.aps.org/doi/10.1103/PhysRevB.75.155410.
doi:10.1103/PhysRevB.75.155410
12. Zhu, H. L., S. W. Cheung, K. L. Chung, and T. I. Yuk, "Linear-to-circular polarization conversion using metasurface," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 9, 4615-4623, Sep. 2013. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6529103.
doi:10.1109/TAP.2013.2267712
13. Zhou, B. and T. J. Cui, "Directivity enhancement to vivaldi antennas using compactly anisotropic zero-index metamaterials," IEEE Antennas and Wireless Propagation Letters, Vol. 10, 326-329, 2011. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=5749686.
doi:10.1109/LAWP.2011.2142170
14. Qi, M. Q., W. X. Tang, H.-X. Xu, H. F. Ma, and T. J. Cui, "Tailoring radiation patterns in broadband with controllable aperture field using metamaterials," IEEE Transactions on Antennas and Propagation, Vol. 61, No. 11, 5792-5798, Nov. 2013. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6576199.
doi:10.1109/TAP.2013.2276921
15. Vallecchi, A., J. R. de Luis, F. Capolino, and F. de Flaviis, "Low profile fully planar folded dipole antenna on a high impedance surface," IEEE Transactions on Antennas and Propagation, Vol. 60, No. 1, 51-62, Jan. 2012. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6018997.
doi:10.1109/TAP.2011.2167912
16. Erentok, A., R. W. Ziolkowski, J. A. Nielsen, R. B. Greegor, C. G. Parazzoli, M. H. Tanielian, S. A. Cummer, B.-I. Popa, T. Hand, D. C. Vier, and S. Schultz, "Lumped element-based, highly sub-wavelength, negative index metamaterials at UHF frequencies," Journal of Applied Physics, Vol. 104, No. 3, 034901, 2008. [Online]. Available: http://scitation.aip.org/content/aip/journal/jap/104/3/10.1063/1.2959377.
doi:10.1063/1.2959377
17. Erentok, A. and R. W. Ziolkowski, "Metamaterial-inspired efficient electrically small antennas," IEEE Transactions on Antennas and Propagation, Vol. 56, No. 3, 691-707, Mar. 2008. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=4463892.
doi:10.1109/TAP.2008.916949
18. Ajith, K. K. and A. Bhattacharya, "Improved ultra-wide bandwidth bow-tie antenna with metamaterial lens for GPR applications," Proceedings of the 15th International Conference on Ground Penetrating Radar, 739-744, Jun. 2014. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6970525.
doi:10.1109/ICGPR.2014.6970525
19. DuHamel, R. and D. Isbell, "Broadband logarithmically periodic antenna structures," IRE International Convention Record, Vol. 5, 119-128, Institute of Electrical and Electronics Engineers, 1958. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1150566.
20. Carrel, R., "The characteristic impedance of two infinite cones of arbitrary cross section," IRE Transactions on Antennas and Propagation, Vol. 6, No. 2, 197-201, Apr. 1958. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1144578.
doi:10.1109/TAP.1958.1144578
21. Chen, E. and S. Chou, "Characteristics of coplanar transmission lines on multilayer substrates: Modeling and experiments," IEEE Transactions on Microwave Theory and Techniques, Vol. 45, No. 6, 939-945, Jun. 1997. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=588606.
doi:10.1109/22.588606
22. Gevorgian, S. and H. Berg, "Line capacitance and impedance of coplanar-strip waveguides on substrates with multiple dielectric layers," 31st European Microwave Conference, 2001, 1-4, Oct. 2001. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=4140229.
23. Simons, R. N., Coplanar Waveguide Circuits, Components, and Systems, ser. Wiley Series in Microwave and Optical Engineering, John Wiley & Sons, Inc., Mar. 2001. [Online]. Available: http://doi.wiley.com/10.1002/0471224758.
doi:10.1002/0471224758.ch1
24. Pfeiffer, C. and A. Grbic, "Metamaterial huygens surfaces: Tailoring wave fronts with reflectionless sheets," Physical Review Letters, Vol. 110, No. 19, 197401, May 2013. [Online]. Available: http://link.aps.org/doi/10.1103/PhysRevLett.110.197401.
doi:10.1103/PhysRevLett.110.197401
25. Ginis, V., P. Tassin, T. Koschny, and C. M. Soukoulis, "Broadband metasurfaces enabling arbitrarily large delay-bandwidth products," Applied Physics Letters, Vol. 108, No. 3, 031601, Jan. 2016. [Online]. Available: http://scitation.aip.org/content/aip/journal/apl/108/3/10.1063/1.4939979.
doi:10.1063/1.4939979
26. Schantz, H., "Radiation efficiency of UWB antennas," 2002 IEEE Conference on Ultra Wideband Systems and Technologies (IEEE Cat. No. 02EX580), 351-355, 2002. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1006392.
doi:10.1109/UWBST.2002.1006392
27. Lestari, A., A. Yarovoy, and L. Ligthart, "Adaptive wire bow-tie antenna for GPR applications," IEEE Transactions on Antennas and Propagation, Vol. 53, No. 5, 1745-1754, May 2005. [Online]. Available: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=1427933.
doi:10.1109/TAP.2005.846726