An important issue in antenna array design is reduction of mutual coupling. In square microstrip antennas this reduction can be achieved by using electromagnetic band-gap (EBG) structures. They can help in the reduction of mutual coupling by using their capability of suppressing surface waves propagation in a given frequency range. In this paper, we analyze the isolation properties of different EBG structures are compare them in antennas arrays by simulations. A new configuration of a planar compact electromagnetic bandgap structure is investigated. Compared to the conventional EBG (mushroom structure), a size reduction of 67.2% is achieved. Simulation results show that a significant value of mutual coupling reduction, more than 6 dB, can be obtained by using the proposed structure.Index Terms----Electromagnetic-bandgap (EBG), mutual coupling, structures, microstrip antenna arrays, surface wave.

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In this article, a novel T-shaped compact dielectric resonator antenna for ultra-wideband (UWB) application is presented and studied. The proposed DRA structure consists of T-shaped dielectric resonator fed by stepped microstrip monopole printed antenna, partial ground plane and an inverted L-shaped stub. The inverted L-shaped stub and parasitic strip are utilized to improve impedance bandwidth. A comprehensive parametric study is carried out using HFSS software to achieve the optimum antenna performance and optimize the bandwidth of the proposed antenna. From the simulation results, it is found that the proposed antenna structure operates over a frequency range of 3.45 to more than 28 GHz with a fractional bandwidth over 156.12%, which covers UWB application, and having better gain and radiation characteristics.

In this paper, a coplanar waveguide (CPW) fed slot antenna using fractal-shaped isosceles trapezoidal corrugations is designed and presented for Ultra-Wideband (UWB) applications. The proposed antenna is formed by a regular hexagonal patch fed through a CPW feed line and radiates amidst a notched wide hexagonal slot. The edge of the wide slot is shaped by a fractal structure that is formed by five trapezoidal notches. The antenna is printed on RO4350B substrate having a compact size of 0.305λ0 × 0.313λ0 × 0.012λ0 at 2.35 GHz. . Good agreement is registered between the experimental results of the fabricated prototype and the calculated ones. By using an Agilent 8722ES vector network analyzer, the fabricated prototype confirms that the antenna has an excellent matching impedance over the bandwidth 2.35-10.65 GHz (127%) which covers the entire UWB band. Furthermore, good radiation performances are measured in an anechoic chamber. Consistent radiation patterns with a reasonable peak gain are measured over the entire working bandwidth. Therefore, the designed structure may be worthily considered for different wireless communications systems.

This paper presents an efficient execution of the Wave Concept Iterat ive Procedure algorith m (WCIP) combined with the Multi-scale approach's module (M.WCIP). This approach is introduced to solve the problem of the relationship between circuit co mplexity and computation time. Therefore, this work consists of a development of simu lation software based on this combination fo r planar circuits very jagged structure's simulat ion. The t wo layouts of the micro -strip trisection filter's simulation are made. The first layout has a higher selectiv ity on the high side of the pass-band and the second has a higher selectivity but on the low side of the pass-band. The results obtained the WCIP and M.WCIP are analyzed and validated by comparison with results obtained by other researchers.