Short-pulse Ground Penetrating Radar Research Articles

Metamaterial slabs enhanced modified antipodal Vivaldi antenna

A metamaterials slabs covered antipodal Vivaldi antenna (MSCAVA) is proposed herein to improve directivity and gain. The proposed metamaterials slabs have a higher effective permittivity than the substrate. The design process of proposed MSCAVA is presented, along with the comparison with other existing works. The simulated and measured results show that the −10 dB bandwidth of the proposed antenna is 1.5 to 8 GHz while the E-planes' and H-planes' half-power beamwidth have been effectively reduced. The maximum gain is 16.4 dBi at 8 GHz. Owing to those good properties, the proposed MSCAVA could be used in short-pulse ground penetrating radar and other situations where need high gain and directivity.

A Compact Vivaldi Antenna With Artificial Material Lens and Sidelobe Suppressor for GPR Applications

A novel compact Vivaldi Antenna (CVA) for short-pulse ground penetrating radar (GPR) systems is presented. Artificial materials lens (AML) and sidelobe suppressor (SSR) are loaded to improve GPR Antenna’s radiation capability in the aperture and the flanks of the CVA. The simulation and experimental results indicate that the proposed CVA has a −10 dB impedance bandwidth of 100% (0.7-2.1 GHz) and a −3 dB gain bandwidth of 70.9% (1.0-2.1 GHz). Within the operating bandwidth of the CVA, AML primarily enhances the CVA’s high-frequency gain (1.4-2.1GHz), while the SSR primarily enhances the CVA’s low-frequency gain (0.7-1.4 GHz). Moreover, the CVA loaded with two kinds of artificial materials (AMs) has an average gain of 1 dB and 2 dB in the low-frequency and high-frequency parts, respectively. In addition, the transmission response with small ringing in time domain makes the proposed CVA suitable for short-pulse GPR systems. AML and SSR effectively enhance the gain of the CVA with a compact and space-saving loading method, which provides a new idea to enhance the gain of the CVA by artificial material.

Ultrawideband Antipodal Tapered Slot Antenna With Gradient Refractive Index Metamaterial Lens

This letter proposes an ultrawideband and high-gain antipodal tapered slot antenna (ATSA) with a gradient refractive index (GRIN) lens. The GRIN lens consisting six metamaterial lenses is placed in the maximum radiation direction of the ATSA to greatly enhance its radiation capability. We found that the proposed GRIN lens antenna has a wide impedance bandwidth of 175.7% (0.84–13 GHz) and −3 dB gain bandwidth of 65.8% (5.86–11.6 GHz). Its gain is averagely increased by 4.81 dB in the whole operating band, and the maximum gain reaches 20.55 dBi at 9.5 GHz. The simulation and measured results demonstrate that the designed GRIN lens antenna has an excellent performance and is suitable for short-pulse ground penetrating radar systems.

A Compact Antipodal Tapered Slot Antenna With Artificial Material Lens and Reflector for GPR Applications

A novel compact antipodal tapered slot antenna (ATSA) for short-pulse ground penetrating radar (GPR) systems is presented. In order to improve the GPR antenna’s radiation capability, we load the artificial material (AM) lens and reflector in the blank area of the antenna’s substrate. Benefiting from the planar and compact structure of AM lens and reflector, original ATSA’s directivity and radiation gain can be enhanced without decreasing its bandwidth or increasing any additional burden. To validate the proposed ATSA’s performance, two prototypes (with and without AMs) are simulated, fabricated, measured, and compared. The simulation and experimental results indicate that the proposed ATSA has a −10 dB impedance bandwidth of 176.9% (0.43–7.0 GHz) and a −3 dB gain bandwidth of 111.1% (2.0–7.0 GHz). Besides, the radiation gain has been improved by about 2 dB while keeping the stable and endfire patterns over the frequency band. In addition, the transmission response in time domain indicates that it has a small ringing. The proposed ATSA is suitable for short-pulse GPR systems due to its excellent radiation performance. The introduced AM lens and reflector provide an effective way to improve antenna performance, which can be used in many other wireless systems.

Design of a resistively loaded vee dipole for ultrawide-band ground-penetrating Radar applications

A new resistively loaded vee dipole (RVD) is designed and implemented for ultrawide-band short-pulse ground-penetrating radar (GPR) applications. The new RVD is improved in terms of voltage standing wave ratio, gain, and front-to-back ratio while maintaining many advantages of the typical RVD, such as the ability to radiate a short-pulse into a small spot on the ground, a low radar cross section, applicability in an array, etc. The improvements are achieved by curving the arms and modifying the Wu-King loading profile. The curve and the loading profile are designed to decrease the reflection at the drive point of the antenna while increasing the forward gain. The new RVD is manufactured by printing the curved arms on a thin Kapton film and loading them with chip resistors, which approximate the continuous loading profile. The number of resistors is chosen such that the resonant frequency due to the resistor spacing occurs at a frequency higher than the operation bandwidth. The antenna and balun are made in a module by sandwiching them between two blocks of polystyrene foam, attaching a plastic support, and encasing the foam blocks in heat-sealable plastic. The antenna module is mechanically reliable without significant performance degradation. The use of the new RVD module in a GPR system is also demonstrated with an experiment.

Optimization of short-pulse GPR transmit antenna

By analyzing the current distribution of Bow-Tie antenna used in short-pulse ground penetrating radar, the methods of antenna load and driving are presented in this paper to reduce strength of reflective wave both at antenna end and excitation point. The numerical simulation results show the strength of reflective wave is smaller than −55 dB comparing with the driving wave when the methods are adopted.

Land mine detection using a ground-penetrating radar based on resistively loaded Vee dipoles

Resistively loaded Vee dipoles are considered for use in a short-pulse ground penetrating radar (GPR) used to detect buried antipersonnel land mines. First, a study is made to select a short pulse to radiate that is most appropriate for the problem. A simple one-dimensional (1-D) analysis of some representative soils and a land mine is used to select a radiated pulse similar in shape to a differentiated Gaussian pulse with a spectral peak at 4 GHz. Based on previous studies, the conductivity of the arms of the Vee dipole is linearly tapered from the feed to the open ends. A fully three-dimensional (3-D) finite-difference time domain (FDTD) model is developed and used to simulate the GPR land mine detection problem. Using this model, a resistively loaded Vee dipole is selected and evaluated. Parametric studies related to the problem are conducted including: varying the height of the Vee above the ground, varying the position of the land mine both laterally and in depth, and examining the effects of the geometry of the land mine on the received signal. Environmental conditions are examined including signal returns from rocks and variations in the shape of the surface of the ground. The FDTD results are validated by comparisons with experimental data. These studies demonstrate that resistively loaded Vee dipoles can greatly reduce clutter related to the antenna, making the task of distinguishing land mines (targets) much easier.

Ultra-wideband, short-pulse ground-penetrating radar: simulation and measurement

Ultra-wideband (UWB), short-pulse (SP) radar is investigated theoretically and experimentally for the detection and identification of targets buried in and placed atop soil. The calculations are performed using a rigorous, three-dimensional (3D) method of moments algorithm for perfectly conducting bodies of revolution. Particular targets investigated theoretically include anti-personnel mines, anti-tank mines, and a 55-gallon drum, for which the authors model the time-domain scattered fields and the buried-target late-time resonant frequencies. With regard to the latter, the computed resonant frequencies are utilized to assess the feasibility of resonance-based buried-target identification for this class of targets. The measurements are performed using a novel UWB, SP synthetic aperture radar (SAR) implemented on a mobile boom. Experimental and theoretical results are compared.

Vee dipoles with resistive loading for short-pulse ground-penetrating radar

The worldwide crisis due to land mines has given rise to a need for better detection technologies. One means of detecting buried land mines is the short-pulse ground-penetrating radar (GPR). A short-pulse GPR system requires broadband directive antennas. Resistively loaded Vee dipoles, with either constant or linearly tapered conductivity, offer a simple means of achieving such antennas. Vee dipoles have greater directivities than conventional linear dipoles, and the resistive loading can greatly reduce unwanted signals (clutter) due to reflections from the open ends of the dipole arms and multiple reflections between the antenna and the surface of the ground. This clutter can obscure real targets. In most cases, the Vee dipole with a linearly tapered conductivity offers the best performance. © 1996 John Wiley & Sons, Inc.