GA design of broadband thin-wire antennas for GPR applications

Abstract

Abstruct-Cenetic algorithm (CA) are applied to the design of thin-wire antennas for Ground Penetrating Radar (GPR). The broadband characteristics of the antenna are achieved using resistive loading along the wires. In some cases also capacitive loading is considered. The geometries considered are straight thin-wire dipoles. V antennas and a thin-wire bow-tie antenna.lndex Terms-Broadband antennas, Genetic algorithms, Thin-wire antennas.

GA design of a thin-wire bow-tie antenna for GPR applications

“…A specific antenna is defined by: the number of wires (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20); the angular distances between wires; and the number and values of the resistive loads along the wires (ranging from 0-450 ). The different parameters corresponding to a specific antenna are encoded into a chromosome composed of 20 integer digits using fixed-point coding (each integer digit varying from 0-9) and each chromosome consists of six genes.…”

“…In this paper, we present a new design of a resistively loaded thin-wire bow-tie antenna for GPR that minimizes the late-time ringing and therefore can also be used in cases where time-windowing is not possible. In this sense, this work, which was preliminarily introduced in [11], complements and broadens the application range of the designs presented in [9] and [10]. The resistive loads and the specific geometry of the wire antenna have been selected using a genetic algorithm (GA) [12], [13] that maximizes the fidelity of the antenna's response [3] in order to reduce the unwanted reflections of the current at the ends of the wires, enhancing the travelling-wave component of the current and thereby extending the bandwidth.…”

Thin‐wire antenna design for GPR applications using a multi‐objective GA

“…A two‐objective MOGA tool has been developed to optimize the characteristics of thin‐wire antennas for GPR. Although the antennas designed here could be used in numerous GPR applications, the one we had in mind was, as in our previous work (Rubio Bretones et al ), the detection of fractures in a marble quarry in order to improve its management. For this case, it had been proved (Grandjean and Gourry ) that impulse radar with a broadband response of up to approximately 900 MHz provides a good compromise between resolution and penetration depth.…”

“…However, as the antennas are made of metal without any resistive loading, late‐time ringing will eventually arise, limiting the utility of the antennas. Rubio Bretones et al () introduced a resistively loaded thin‐wire bow‐tie antenna, designed with a mono‐objective genetic algorithm (GA), which extends the range of application of the antennas presented by Lestari () and Lestari et al (). The GA maximized the fidelity of the time‐domain antenna response, defined as the cross‐correlation between the current of the antenna (output signal) and the voltage (input signal) at the feeding point.…”

“…The MOGA selects the angular distances between the wires, the elevation angle between the two antenna arms and the specific value of the resistive loading. Initial experiments showed that folding the thin‐wire bow‐tie antenna presented by Rubio Bretones et al () increases the front‐to‐back ratio but at the expense of antenna fidelity. Therefore, the MOGA is an appropriate tool for the problem, as it can deal with conflicting parameters, yielding not just a single optimum solution but a set of optimum solutions, the so‐called Pareto set, from which the designer can select a suitable trade‐off solution (Back ).…”