A.Yu. Grinev, E.V. Ilin, A.P. Volkov

Artificial surfaces with high impedance (HIS), used to create a low-profile antennas, allow to control the radiation pattern, input impedance and radiation efficiency. They are often described as artificial magnetic conductors, since the tangential component of the magnetic field is zero and the reflection coefficient of such a structure is equal to +1. The article provides a technique which allows the analytical estimates and numerical simulation results to choose the parameters of the surface of the high-impedance-based artificial dielectric for low-profile dipole antennas in the decimeter range with technologically realizable parameters of the cell. In the first phase evaluated the surface impedance, resonant frequency, the reflection coefficient and the operating frequency band HIS using analytical estimates and the results of numerical simulation using finite-difference time-domain (FDTD) and finite element (FE) methods. Consider the influence of basic parameters of HIS on the phase of reflection coefficient, allowing the size of HIS to agree with the resonance frequency and the operating frequency band antenna. In the second phase, a numerical simulation of the printed dipole antenna on a substrate HIS. To calculate the SWR of printed dipole antenna on a substrate HIS selected two approaches. The first is based on the calculation of the impedance of the vibrator subject to HIS. Accordingly, to calculate the SWR first calculated own and induced impedance of the structure (two uniform phase dipoles located on two sides of the dielectric). Next, to calculate the impedance of the vibrator was added phase of the reflection coefficient of the HIS. In the second approach was carried out a complete modeling of the structure of HIS - a printed dipole FDTD and FE methods. In the modeling FDTD method used grid increments . The volume model was divided into 124 960 cells. On a computer with an Intel Pentium IV 3 GHz, Hyper Threading with 3 GB of RAM calculation was 8 minutes. When you use the FE mesh consisting of 9908 tetrahedra, has been involved in the calculation of 212 MB of RAM. On the computer calculation for a single frequency was 25 seconds. The above technique allows to calculate the parameters of the surface with a high impedance on the basis of an artificial dielectric for low-profile dipole antennas with realizable technological parameters of the cell. With a thickness of 11.21 mm HIS frequency band is 30% for SWR = 2.