Miniaturized and flexible FSS-based EM shields for conformal applications

This article reports on very efficient and highly miniaturized wideband polygon-shaped frequency selective surface (PFSS) shields for the planar and conformal applications in the X-band. These shields have been analyzed for both lossy as well as for low-loss substrates. The conformal configurations of PFSS are particularly investigated for inward, outward, and double-curved profiles useful for a variety of applications. The conformal designs have been tested for two different radii of curvatures. The models have been simulated using a hybrid simulation approach for electrically large geometries. The equivalent circuit model as well as the analytical model are determined. The proposed PFSS designs offer stable angular response up to 60° for planar and all conformal geometries on both lossy and low-loss prototypes. Shielding effectiveness of at least 55 dB and 48 dB has been measured for flat/nonconformal and conformal configurations, respectively

A Switchable frequency selective surface based on a modified Jerusalem-cross unit cell

This paper presents a switchable frequency selective surface (FSS) based on a modified Jerusalem-cross (JC) unit cell. To make it switchable, various combinations of switches have been considered and the corresponding FSS behavior has been analyzed. It was found that the pass bands can be changed by turning switches ON or OFF appropriately. For example, a single pass band can be achieved at a lower frequency of 2.45 GHz or at a higher frequency of 5 GHz. Results also demonstrate that dual or triple pass bands can also be achieved by selecting other switch combinations. It is noted that for several switch combinations the lower band has a stable resonance frequency while the higher band has a variable resonance frequency.2 page(s

A Switchable FSS based on modified Jerusalem-cross unit cell with extended top loading

This paper presents a switchable frequency selective surface (FSS) based on a modified Jerusalem-cross (JC) unit cell with extended top loading. Various combinations of switches are considered to make it switchable and the corresponding FSS behavior is analyzed. It is noted that the pass band(s) and stop band can be achieved by turning switches ON or OFF appropriately. For example, as a band pass FSS, it can provide single wide-band operation covering a bandwidth of 1.5GHz (2.97-4.47 GHz). In another mode, two narrower pass bands, one around 2.4GHz and other around 5.4GHz, can be achieved. Third mode allows a very wide stop band. The proposed FSS unit cell has been designed for fabrication on FR-4 to provide an inexpensive reconfigurable solution.2 page(s

A Compact Quad-Element UWB-MIMO Antenna System with Parasitic Decoupling Mechanism

This research work proposes a compact four-port multiple-input multiple-output (MIMO) antenna that operates in the whole license free ultra-wideband (UWB) spectrum of 3.1–10.6 GHz. Spatial diversity has been introduced by arranging these antennas in close proximity without developing a strong mutual coupling. Antenna elements are evolved from a conventional rectangular patch antenna whereas a customized decoupling structure is introduced on the back side of the substrate to achieve the desired isolation level. The parasitic decoupling structure consists of different features which are resonant at different frequencies offering a whole UWB coverage. In addition to the decoupling structure a dumbbell shaped stub has also been introduced to the partial ground plane to suppress the mutual coupling. The overall measured isolation among elements is more than 20 dB. Different MIMO performance parameters have also been investigated from the measured results. Whole MIMO system measures 0.41 λo × 0.44 λo at 3.1 GHz. The MIMO system is intended for high data rate and short-range communication devices used in wireless personal area networks