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A novel double-layer multiband, low-profile frequency selective surface (FSS) for IMT-Advanced (4G) mobile communication system is presented in this article. On aspired to a minimum transmission coefficient of -10 dB for surface materials when the frequency bands targeted for blocking are stopped. For this project, we chose the dielectric substrate FR4 (loss-tangent = 0.02; dielectric constant = 4.54) and a thickness of 1 mm. Dodecagonal rings, upright bars, and square frame make up the FSS unit cell. The desired frequency responses of the FSS were intended to avoid being changed according to the angle of incidence of the electromagnetic waves. The FSS design is proposed as a symmetrical structure to make it polarization-independent and is aimed to stop 800, 900, 1800, 2100, and 2600 MHz frequencies to prevent harmful effects to human health and interference effects at these frequencies. With a cell size of 0.17λ, the planned FSS is quite small and, thus, has a low sensitivity at the angle of the incident wave. In addition, FSS geometry was manufactured by a printed circuit board (PCB) and measured in a non-reflective environment after being studied in Ansys high-frequency structure simulator (HFSS) software. By comparing the analysis and measurement results of the design, the success of the FSS to the frequencies to be stopped has been verified. The effect of each patch on different frequencies has been examined by drawing the surface current density graphs of the design. [ABSTRACT FROM AUTHOR]

Low-cost antennas are suggested for 5.8 GHz narrow-band, low-power and dual-polarized wireless bridges based on pure microstrip flat reflectarrays. A single layer of the cheapFR4 epoxy is exploited as the substrate for both of the feed and reflector. Detailed design procedure for the feed is reported. Three different elements are used for designing the reflector including rectangular dipole, unbalanced cross and square patch. Using method of moments, performance of the designs is compared from various aspects, including reflector diameter, computational cost, gain, half-power beamwidth and polarization purity. [ABSTRACT FROM AUTHOR]

A hybrid fractal multiband antenna is designed by integrating Koch curve and meander antenna. Scripting method (*.vbs) is adopted to obtain the hybrid fractal structure using IFS and MATLAB. Final structure is obtained by perturbing the reference fractal shape. Proposed antenna exhibits multiband characteristics capable of operating in four different wireless frequency bands including very popular Bluetooth (2.4 GHz), WiMAX (3.4-3.7 GHz), WLAN 802.11 a/b/g (5.3-6.1 GHz) and Aeronautical radionavigation (8.68-9.05GHz). The antenna has a planar structure, compact size of 39 mm × 32 mm × 1.58 mm and is suitable for wireless applications. Prototype of the proposed structure is developed on easily available and low cost FR4 substrate. The antenna has acceptable values of return loss, VSWR and gain. Measured characteristics are in good agreement with the simulated one. [ABSTRACT FROM AUTHOR]