A modified bow-tie antenna for improved pulse radiation
Lestari A.A.a,b, Bharata E.a, Suksmono A.B.a, Kurniawan A.a, Yarovoy A.G.b, Ligthart L.P.b
a International Research Centre for Telecom and Radar (IRCTR), Bandung Institute of Technology, Indonesia
b IRCTR, Delft University of Technology, Netherlands
Abstract
The analysis, design, and realization of a modified bow-tie antenna optimized for impulse ground penetrating radar (GPR) applications is described. The proposed antenna shows improved properties important for GPR, which include its compact size (in comparison with a conventional bow-tie antenna) and ability to radiate UWB pulses with increased amplitude and very small late-time ringing. A substantial increase in the amplitude of the transmitted pulse is achieved by utilizing radiation from discontinuities introduced by the resistive loading employed in the antenna to suppress late-time ringing. By choosing an optimal distance between the antenna’s feed point and the location of the resistive loading, radiations that occur from the antenna’s feed point and the mentioned discontinuities at the resistive loading will combine constructively in the boreside direction of the antenna. As a result, one will observe a substantial increase of the amplitude of the transmitted pulse in the boreside direction. Furthermore, an analytical expression describing approximate time-harmonic current distribution is derived to indicate an optimal resistive loading profile for the proposed antenna. Additionally, the traveling-wave current distribution of the antenna is theoretically analyzed to examine the applicability of the obtained time-harmonic expression for pulse excitation. It has been found that when the antenna is resistively loaded both the time-harmonic and traveling-wave currents decay to approach nearly the same value at the end section of the antenna. As the amount of current at the antenna ends corresponds to the level of reflection which occurs there, the derived expression is found to be useful to indicate an optimal loading profile for the proposed antenna. A theoretical model of the proposed antenna has been developed to perform numerical analysis using a modified NEC-2 code. In addition, an experimental verification has been carried out and both the simulation and experiment confirmed the improved properties of the proposed antenna. © 2006 IEEE.
Author keywords
Analytical expressions,Bow-tie antennas,Compact size,Experimental verification,Feed point,Ground penetrating radars,Optimal loading,Pulse excitation,Pulse radiation,Resistive loading,Theoretical models,Time-harmonic,Transmitted pulse,Traveling wave,Ultra-wideband antennas,UWB pulse
Indexed keywords
Bow-tie antenna,ground penetrating radar (GPR),resistive loading,ultrawideband (UWB) antenna
Funding details
Manuscript received April 12, 2009; revised December 21, 2009; accepted January 25, 2010. Date of publicationApril 22, 2010; date of current version July 08, 2010. This work was supported in part by the International Research Centre for Telecommunications and Radar (IRCTR)—Delft University of Technology, The Netherlands, and Radar & Communication Systems (RCS), Indonesia.