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Miniaturized circular patch antennas loaded by helices, which operate as -negative (MNG) metamaterials, is reported. Two antennas having different helix parameters have been fabricated. The patch radius for both antennas is 42 mm. The first fabricated antenna shows a resonance at 1.126 GHz, which corresponds to a 40% size reduction. The second antenna has an even better size reduction of 60%. Measured results of return loss and radiation pattern at the subwavelength resonances are compared to these parameters at the conventional resonance of the patch antenna.Index Terms-Electrically small antennas, metamaterials, patch antennas.

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A novel dual-frequency dual-linear-polarization printed antenna element benefiting from a single-feed single-layer structure is introduced in this paper. The Boolean particle swarm optimization algorithm in conjunction with the method of moments (MoM) is employed to optimize the geometry of the antenna after considering three objectives: cross polarization, return loss, and boresight direction in both bands. A fuzzy-logic based ordered weighted averaging operator allows us to efficiently implement the multi-objective optimization technique. Prototypes of the optimized designs have been fabricated and tested. The measured results show excellent performance with more than 15 dB of return loss and 10 dB of cross polarization in both frequency bands of operation, i.e., 12 and 14 GHz. A gain of 4.8 dBi has been measured for both frequency bands.Index Terms-Advanced optimization techniques in electromagnetics, Boolean particle swarm optimization (BPSO), dual-band dual-polarized printed antenna, fuzzy logic.