Compensated circuit with characteristics of lossless double negative materials and its application to array antennas

A compensated circuit showing the characteristics of lossless double negative (DNG) materials is proposed and applied to an active integrated antenna array. A properly selected matching circuit produces the phase advance, which is characteristic of a left-handed wave (backward-wave), and the lossy resonant circuit generates the negative group velocity. An amplifier is used to compensate for the inherent loss of the resonant circuit, including its resistor. Then, a series-fed antenna array with a proposed DNG circuit is also designed and fabricated. It consists of two subarrays, each made of two aperture-coupled patch antennas, and the DNG circuit block inserted between the subarrays. In comparison to a conventional array, without the DNG circuit whose two subarrays are connected directly by a microstrip line, the proposed array shows a negligible beam squint and flat gain, over a considerable bandwidth of 11%.