The properties and characteristics of a recently proposed anisotropic metamaterial based upon layered arrays of tightly coupled pairs of "dogbone" shaped stripe conductors have been explored in detail. It has been found that a metamaterial composed of such stacked layers exhibits artificial magnetism and may support backward wave propagation. The equivalent network models of the constitutive conductor pairs arranged in the periodic array have been devised and applied to the identification of the specific types of resonances, and to the analysis of their contribution into the effective dielectric and magnetic properties of the artificial medium. The proposed "dogbone" configuration of conductor pairs has the advantage of being entirely realizable and assemblable in planar technology. It also appears more prospective than simple cut-wire or metal-plate pairs because the additional geometrical parameters provide an efficient control of separation between the electric and magnetic resonances that, in turn, makes it possible to obtain a fairly broadband left-handed behaviour of the structure at low frequencies.

Abstract-In printed phased arrays, scan blindness occurs when the propagation constant of a Floquet mode coincides with that of a mode supported by the homogeneous substrate, resulting in large input mismatch and in a propagating mode with complex propagation constant. In our study we analyze the possibility to replace a standard homogeneous dielectric substrate with a grounded dielectric EBG substrate to eliminate scan blindness. We present here the main idea for the design, the dispersion diagrams of a dielectric EBG material with metallic patches to show that there are no surface modes (waves guided by the structure with real propagation constant), and the active reflection coefficient and input impedance for various frequencies. Furthermore, at a chosen operating frequency the active reflection coefficient for the phased case indicates that there is no scan blindness effect.Index Terms-Arrays, band gap, dielectric resonators, electromagnetic bandgap (EBG) materials, phased arrays, scan blindness.

Antennas with large gain are obtained here with one or few radiators. The main idea consists of inserting simple radiating elements, as patches, inside a Fabry-Perot Cavity (FPC) resonator. This consists of a ground plane covered by a partially reflecting surface (PRS). We provide here some simple rules for the design of such systems, paying attention to a) the required bandwidth and gain, and b) the equivalent model of the periodic surface that forms the PRS, with the goal of designing large antenna gain by using arrays with thinned number of elements. In the present investigation we obtain 19 dB gain with a 2x2 array with a bandwidth of 3.6%.

IntroductionElectromagnetic Bandgap (EBG) materials have found possible applications in the antenna technology (see [1] as example) as substrates to improve performances like reducing mutual coupling between antennas or reduce side lobe effects due to truncated surface waves that would be excited in a standard antenna substrate. EBG substrates can also be used to eliminate scan blindness phenomena presented in array antennas [2], and in [3][4] EBG layers have also been used as a top cover of a Fabry-Perot Cavities to produce highly-directive radiators.