In this paper, the bandwidth of a bowtie antenna is improved to meet the requirements of Ground Penetrating Radar (GPR) applications that need a fractional bandwidth greater than 100% and are able to operate at low frequencies. This was done using several modification steps, which were the use of Antipodal technique for its advantages in reducing the complexity of the feeder network to achieve good matching with a standard 50-Ω SMA connector, bending the four corners of the arms and adding a triangular slot in each arm. The simulation was carried out using CST Microwave Studio to study the effect of each modification step on improving the bandwidth. The simulation results of the new antenna achieved a fractional bandwidth of 138% within the frequency range (1-5.45) GHz at the values of return loss (S11≤-10 dB). The new antenna was also fabricated, and the return loss was measured and showed a good agreement with the simulation results.
2. Nayak, R. and S. Maiti, "A review of bow-tie antennas for GPR applications," IETE Technical Review, Vol. 36, No. 4, 382-397, Jul. 2019.
3. Sayidmarie, K. H. and Y. A. Fadhel, "A planar self-complementary bow-tie antenna for UWB applications," Progress In Electromagnetics Research C, Vol. 35, 253-267, 2013.
4. Dadgarpour, A., G. Dadashzadeh, M. Naser-Moghadasi, and F. Jolani, "Design and optimization of compact balanced antipodal staircase bow-tie antenna," Antennas Wirel. Propag. Lett., Vol. 8, 1135-1138, 2009.
5. Ali, J., N. Abdullah, M. Yusof, E. Mohd, and S. Mohd, "Ultra-wideband antenna design for GPR applications: A review," IJACSA, Vol. 8, No. 7, 2017.
6. Wu, Y., F. Shen, Y. Yuan, and D. Xu, "An improved modified universal ultra-wideband antenna designed for step frequency continuous wave ground penetrating radar system," Sensors, Vol. 19, No. 5, 1045, Mar. 2019.
7. Ting, J., D. Oloumi, and K. Rambabu, "A miniaturized broadband bow-tie antenna with improved cross-polarization performance," AEU - International Journal of Electronics and Communications, Vol. 78, 173-180, Aug. 2017.
8. Sagnard, F. and F. Rejiba, "Wide band coplanar waveguide-fed bowtie slot antenna for a large range of ground penetrating radar applications," IET Microw. Antennas Propag., Vol. 5, No. 6, 734, 2011.
9. Nayak, R., S. Maiti, and S. K. Patra, "Design and simulation of compact UWB Bow-tie antenna with reduced end-fire reflections for GPR applications," 2016 International Conference on Wireless Communications, Signal Processing and Networking (WiSPNET), 1786-1790, Chennai, India, Mar. 2016.
10. Awl, H. N., et al., "Bandwidth improvement in bow-tie microstrip antennas: The effect of substrate type and design dimensions," Applied Sciences, Vol. 10, No. 2, 504, Jan. 2020.
11. Qu, S. and C. L. Ruan, "Effect of round corners on bowtie antennas," Progress In Electromagnetics Research, Vol. 57, 179-195, 2006.
12. Shao, J., G. Fang, Y. Ji, and H. Yin, "Semicircular slot-tuned planar half-ellipse antenna with a shallow Vee-cavity in vital sign detection," IEEE J. Sel. to Appl. Earth Observations Remote Sensing, Vol. 7, No. 3, 767-774, Mar. 2014.
13. Marsh, L. A., et al., "Combining electromagnetic spectroscopy and ground-penetrating radar for the detection of anti-personnel landmines," Sensors, Vol. 19, No. 15, 3390, Aug. 2019.
14. Ajith, K. K. and A. Bhattacharya, "Printed compact lens antenna for uhf band applications," Progress In Electromagnetics Research C, Vol. 62, 11-22, 2016.
15. Li, K., T. Dong, and Z. Xia, "Improvement of bow-tie antenna for ground penetrating radar," 2019 International Conference on Microwave and Millimeter Wave Technology (ICMMT), 1-3, Guangzhou, China, May 2019.
16. Vijayalakshmi, J. and G. Murugesan, "Improved bandwidth and gain in ultra-wideband staircase antipodal bowtie antenna with rounded edge for microwave imaging applications," Appl. Math. Inf. Sci., Vol. 12, No. 6, 1197-1202, Nov. 2018.
17. Dastranj, A., "Design and implementation of a compact super-wideband printed antipodal antenna using fractal elements," Journal of Communication Engineering, Vol. 7, No. 1, 12, 2018.
18. Ganguly, D., Y. M. M. Antar, A. Somagani, and C. Saha, "Design of an antipodal bowtie array MIMO antenna for 5G mobile applications," 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, 421-422, Atlanta, GA, USA, Jul. 2019.
19. Li, M., C. Domier, X. Liu, and N. C. Luhmann, "Wide band MM-wave, double-sided printed bow-tie antenna for phased array applications," 2015 IEEE International Symposium on Antennas and Propagation & USNC/URSI National Radio Science Meeting, 2063-2064, Vancouver, BC, Canada, Jul. 2015.
20. Joula, M., V. Rafiei, and S. Karamzadeh, "High gain UWB bow-tie antenna design for ground penetrating radar application," Microw. Opt. Technol. Lett., 2018.
21. Balanis, C. A., Antenna Theory Analysis and Design, 4th Ed., Wiley, 2016.
22. Woo, D. S., Y. K. Cho, and K. W. Kim, "Balance analysis of microstrip-to-CPS baluns and its effects on broadband antenna performance," International Journal of Antennas and Propagation, Vol. 2013, 1-9, 2013.