Miniaturised frequency selective surface based on fractal arrays with square slots for enhanced bandwidth

Abstract

A novel approach is used to miniaturise the array size and broaden the bandwidth (BW) of a multilayer antenna‐filter antenna‐ based frequency selective surface (FSS). Although such FSSs have broadly been investigated for higher frequency selectivity and less thickness, they still own high periodicity and lower BW. The proposed fractal FSS with centre square slots consists of three metallic layers, separated by two dielectric substrates and periodicity of the unit cell is sub‐wavelength order (0.2λₒ). Central square slots are added in the external Minkowski fractal patches to increase the capacitive effect whereas fractal slots are etched on the ground placed in the middle for enhanced coupling. It is demonstrated through simulations that proposed design can effectively minimise the element size and enhance the BW. Owing to minuscule array size and symmetric fractal geometry, the presented structure is insensitive to higher incidence angles (up to 30°) for both polarisations. A prototype of the proposed FSS is also fabricated and tested in a microwave anechoic chamber. An equivalent circuit model, full wave simulation and measurement results agree well and demonstrate stable response with 3 dB fractional BW approaching 87.4 and 92%, respectively, at a normal angle of incidence.

Inductively coupled triple layers of ultra‐miniaturized frequency selective surface for L‐band applications

“…By adopting this inductive coupling methodology, the FSS unit cell size is 89%, 29%, 65%, 87%, 41%, 98%, 92%, 88%, 36%, 85%, and 400% smaller on comparing to literatures. [1][2][3][4][5][6][7][8][9][10]16 • The proposed FSS gives a stable response with a wide operating bandwidth of 400 MHz for various incident angles of EM waves up to 60 . Whereas the work demonstrated in the literature [1][2][3][4][5][6][8][9][10][11][12][13][14] provides partial angular stability and lower operational bandwidth for the lower resonant frequency.…”

Design of an Inductive Spiral-Loop Loaded Unit Cell in a Mushroom-Shaped High Impedance Surface for Sub-GHZ Applications

“…A key to the reduction in the resonant frequency of a HIS is the realization of high inductance at the given dimension. Fractal geometries would also be employed to achieve high inductance for a HIS [19,20]. For example, a fractal loop inductor has considerable long electrical traces because of its a mathematical fractal pattern [21,22].…”

Performance evaluation of compact FSS‐integrated flexible monopole antenna for body area communication applications

“…In the recent literature, many design configurations have been studied to incorporate fractal‐inspired antennas to provide compactness, dual‐band, and wide‐band for wearable applications 4–8 . Many frequency selective surface (FSS) structures have been reported 9–14 in the literature to alter the radiation characteristics of the antenna for the desired applications. A polygon‐shaped miniaturized FSS is presented as an electromagnetic shield for conformal applications 11 .…”

“…A polygon‐shaped miniaturized FSS is presented as an electromagnetic shield for conformal applications 11 . Convoluted elements and square slots FSS is introduced to obtain compactness of the FSS in previous studies 10,13 . AFSS array elements consist of a slotted cross dipole combined with four ring patches that are presented 12 to achieve dual‐band rejection.…”