Abstract-The finite difference time domain (FDTD) method is used to analyze a practical ground penetrating radar (GPR) antenna system operating above lossy and dispersive grounds. The antenna is of the resistor-loaded bow-tie type and the analysis is made for two known soil types, namely Puerto Rico and San Antonio clay loams. The soil is modeled by a two term Debye model with a static conductivity and it is matched to the mentioned soils by using curve fitting. The FDTD scheme is implemented by the auxiliary differential equation (ADE) method together with the uniaxial perfectly matched layer (UPML) absorbing boundary conditions (ABC). In order to model a real GPR environment, ground surface roughness and soil inhomogeneities are also included. The effect of soil properties on the GPR response and antenna input impedance is presented. Thus the ability to detect buried metal and plastic pipes is investigated.

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Abstract-Design of multiband antennas with low volume is of practical interest for the ever growing wireless communication industry.In this regard, the design of a small multi band microstrip patch antenna (MPA) for GSM900 (880-960 MHz), GSM1800 (1710-1880 MHz), GSM1900 (1850-1990, UMTS (1920-2170, LTE2300 (2305-2400 MHz), and Bluetooth (2400-2483.5 MHz) applications by using a genetic algorithm (GA) is proposed. The proposed GA method divides the overall patch area into different cells taking into account that cells have a small overlap area between them. This avoids optimized geometries with certain cells having only an infinitesimal connection to the rest of the patch. Therefore, the proposed method is robust for manufacturing. A shorting pin is also included for impedance matching. GA optimization combined with finite element method (FEM) is used to optimize the patch geometry, the feeding position and the shorting position. A prototype has been built showing good agreement with the simulated results. The optimized MPA has a footprint of 46 mm × 57 mm

Abstract-A high-directivity patch antenna with broadside directivity is attractive, since a narrow beam can be obtained without the need of using an array of antennas. Therefore, the solution becomes simpler as there is no need for a complicated feeding network. In this sense, this paper presents a novel patch antenna design with high directivity in the broadside direction by using genetic algorithms (GA). The proposed GA method divides the overall patch area into different cells taking into account that cells have a small overlap area between them. This avoids optimized geometries where cells have only an infinitesimal connection. Therefore, the proposed method is robust for manufacturing. The antenna operates in a higher-order mode at 4.12 GHz and the geometry fits inside a patch of 40 mm × 40 mm on a substrate with a relative permittivity of 3.38 and a thickness of 1.52 mm resulting in a directivity of 10.5 dBi. The specialty of this design is the use of GA to select the optimized shape and the feeding position instead of a known shape and a fixed feeding position. The antenna has been fabricated and the simulation results are in good agreement with the measurements. This results in a simpler design of a single high-directivity patch, which can substitute an array of two elements operating in the fundamental mode.