Beam-squint minimization in microstrip series-fed array antenna using circuit of double negative materials

Double negative (DNG) metamaterials, where both relative permittivity and permeability are negative, show unusual characteristics. In principle an amplifier and properly selected matching circuits can be implemented with DNG circuits to simulate lossless double negative materials. A 4×1 series-fed active array antenna with an amplifier and DNG circuit was designed and fabricated. Its performance was compared with its corresponding conventional array, with direct connections, which was also designed and simulated. Simulated and measured results indicated that, with the DNG array, the variations of beam-squint angle and gain, over a bandwidth of 11%, were reduced considerably. The proposed DNG circuit can therefore find useful applications in several microwave applications including other active array antennas.