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In this article, a novel Ultra‐Wideband (UWB) 180° planar phase shifter is designed and fabricated. The proposed design is mainly based on coupled sections which are realized by inserting slots into the common ground plane of the multilayer circuit. Two identical structures, leading to discard parameters that disturb the output phase shift, are introduced in the design. To get 180° phase difference shift, via holes are used to perform a short circuit in one of the two coupled sections. Theoretical analysis based on four port network is presented to explain the characteristics of the proposed design. Further, experimental measurements are performed and compared with simulation results to validate the proposed approach. Hence, a good simulated to measured agreement is obtained.

This paper describes the design guidelines for frequency independent 180° phase shifters. The proposed configuration is based on microstrip slot transition technique. The frequency independence feature is due to comparing two quasi‐identical structures and the phase inversion (180°) is related to the chosen inverted orientation of the main line compared to the reference one. Moreover, two different schemes are designed and manufactured and a good simulation to measurement agreement is demonstrated. Thus, interesting results are obtained (more than 10 dB return loss, less than 2.1 dB insertion loss and less than ± 3.6° phase deviation).

In this paper, an improved applied approach based on Genetic Algorithm (GA) for antenna design is presented. It is basically useful to overcome electromagnetic interferences in UWB applications. First, an antenna in the range 2.8 - 20 GHz including UWB band was designed by using GA, then the undesired WiMAX band (3.5-3.8GHz) is rejected by optimizing appropriate Defected Ground Structure (DGS) filter. The proposed non-conventional filter consists of a matrix of rectangular cell shapes where each one is allocated by presence or absence of metal. The process is implemented in CST software using visual basic script. The method overcomes difficulties of conventional design. Furthermore, the optimized shape can be automatically obtained without appealing expert designers. Simulated and measured results demonstrate the effectiveness of the proposed design approach.

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This paper deals with the design of a Multiple Input Multiple Output (MIMO) antenna for UWB applications. It is composed of two identical radiating elements (parallel monopoles) symmetrically arranged on a FR-4 substrate. The monopoles are closely spaced (about 0.2 Lambda, center to center). A decoupling mechanism based on vertical extension of the Ground plane with elliptical edges (stub) allows to achieve high isolation (>20 dB). Further, the designed system presents good diversity performance, as the obtained Envelope Correlation Coefficient is less than 0.01. The antenna array is compact (36x30 mm2), with ultra-wide operating frequency range (2.6 to 10.8 GHz). Simulations and measurements demonstrate good agreement. The obtained results make the proposed structure a good candidate for any UWB applications and modern wireless communications systems thanks to its wide frequency band, compactness and performance.