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Design of planar and cylindrical microstrip patch antennas and arrays for smart antenna applications

This paper reports some new designs and results for wireless antennas, which have been developed at the University of Zagreb in cooperation with Dr. Naftali Herscovici, Spike Technologies, Nashua, USA, and the Antenna Group, Chalmers University of Technology in Gothenburg, Sweden. We have developed several programs for different types of geometries, based on the electric field integral equation (EFIE) and on the moment method. In all programs the core subroutine is G1DMULT algorithm which calculates the Green's functions of planar, circular cylindrical, and spherical multilayer structures in spectral domain. Firstly, a shorted stacked patch antenna for linear polarization has been presented. The parasitic patch was slanted in order to obtain broadband operation. Then, we present a broadband planar probe-fed stacked patch structure for circular polarization. The procedure of adding a parasitic element over the driven patch in order to enhance the bandwidth, usual in linearly polarized wideband patches, is investigated in the case of the circular polarization. The results show that this approach may be applied for circularly polarized structures as well. For achieving good performances, the optimization of the antenna parameters was performed using the hybrid optimization technique, consisting of real coded, steady state genetic algorithm and modified Newton method routine. The antenna is modeled using the Method of Moments in Spectral domain. In the following section the description of the antenna design, cost function and optimization procedure is given. In addition, two conformal cylindrical structures are analyzed. The first one is wrapped-around stacked patch antenna. This is a modification of the single patch version with increased operating frequency band. The second one is a microstrip patch array on cylindrical multilayer structure.

stacked patch antenna; shorted patch antenna; wrapped-around patch antenna; antenna array; circular polarization

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