Abstract-A proposed sensor for landmines detection consists of two parallel microstrip antennas placed on the same ground plane and with defected ground structure between them has been investigated. The microstrip patch array with defected ground structure has the advantage of a low mutual coupling compared with the classic one. The Finite-Difference Time-Domain (FDTD) is used to simulate the sensor for landmines detection.

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Dielectric resonator antenna (DRA) shares many of the advantages of microstrip antennas including small size, low profile, light weight and ease of excitation. Moreover, DRA offer more attractive features such as high radiation efficiency, higher impedance bandwidth, and size can be controlled by using different dielectric materials [1,2]. The dependency of the radiation characteristics of cylindrical DRA on the dielectric constant, the resonator dimension, and the ground plane size have been investigated by Kishk et.al.[3].The radiation characteristics of the strip-fed rectangular DRA placed on an infinite ground plane have been experimentally and theoretically investigated in [4].Recently, new ground planes are introduced to electromagnetics called high surface impedance grounds, or perfect magnetic conductors (PMC). The high-impedance ground plane is a metal sheet with a two-dimensional periodic resonant texture that suppresses surface waves in a desired frequency range called the band gap [5][6][7]. This can be beneficial in a variety of antenna applications. The experimental results show that these ground planes are useful in improving the radiation characteristics of the antenna. However, little studies about the dielectric resonator antennas with these ground planes are currently available.Finite-difference time-domain (FDTD) method is used to illustrate the characteristics of strip-fed rectangular dielectric resonator antenna (DRA) over a ground plane with different shapes. The input impedance and the radiation patterns in different planes are calculated and compared with a finite flat PEC ground plane. Throughout this paper, the analysis is performed using FDTD program developed by the authors. II. AnalysisIn this work, the uniform grid FDTD method with 10-cell thick uniaxil perfectly matched layer (UPML) is used [8,9]. The space steps used in all the FDTD simulation are fixed to preserve the same accuracy (∆x=∆y=0.329 mm, and ∆z=0.506 mm), the time step is used to satisfy 0.98 of Courant limit. A Gaussian modulated pulse with sufficient bandwidth is used as the excitation pulse. The modeling of the strip feed is accomplished using the 1D coaxial feed model introduced in [10]. The radiation pattern is calculated using the field equivalence principle in the frequency domain. Fig.1 shows the geometry of a strip-fed rectangular DRA. The feeding strip is placed in the middle of the DRA side wall. The dimensions of the structure are a=14.3 mm, b=25.4 mm, d=26.1 mm, l=10 mm, w=1 mm, and ε r =9.8. To verify the FDTD solution, the impedance properties of the strip-fed rectangular DRA are calculated and compared with measured and numerical results in [4] as shown in Fig.2. The corresponding 11 S of the infinite ground plane with those of finite 1.25λx1.25λ, infinitesimally thin ground plane (designated as the reference antenna for the following discussions) are illustrated in Fig.3., revealing the small effect of the ground plane size on 11 S and also on the input impedance that is not shown here. The radiation p...

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Abstract-A proposed sensor for landmines detection consists of two parallel microstrip antennas placed on the same ground plane and with corrugated ground surface between the arrays has been investigated. The microstrip patch array with corrugated ground surface has the advantage of a low mutual coupling compared with the classic arrays. The Finite-Difference Time-Domain (FDTD) is used to simulate the sensor for landmines detection.