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This article presents a compact size asymmetric CPW strip‐fed UWB two‐element MIMO antenna, with notched‐band behavior. The single‐antenna element of the MIMO configuration is composed of a semi‐elliptical patch radiator with asymmetric ground plane. The notched‐band behavior of the proposed antenna is achieved by inserting a simple folded stub to the patch radiator. This stub achieves the desired single stop‐band from 3.3 to 3.9 GHz for WIMAX. The two‐antenna elements are placed orthogonally to achieve pattern diversity which leads to an improved MIMO system performance and enhances the isolation between elements without using any decoupling structures. The antenna has dimensions of 50 × 28 mm2. The edge‐to‐edge distance between antenna elements is 0.15λ0 at 3 GHz. The proposed antenna is designed, simulated, fabricated, and tested. Results show that the two‐antenna elements operate at frequencies ranging from 2.8 to 11.5 GHz with return loss lower than −10 dB and insertion loss lower than −18 dB. The performance of the MIMO antenna diversity characteristics were verified through the calculation of the standard parameters and show the antenna suitability for MIMO systems. © 2017 Wiley Periodicals, Inc. Microwave Opt Technol Lett 59:1460–1464, 2017

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A design of low mutual coupling between two microstrip patch antennas for multi input multi output antenna is presented. The two antenna elements operate at 5.8 GHz for wireless applications. The reduction of mutual coupling between the antenna elements is achieved by using a defected ground structure (DGS). The DGS is inserted between the microstrip patch antenna elements to limit the surface waves between them. The separation between the edges of the two elements has been achieved to be only 0.058λ0. The analysis of the correlation coefficient, diversity gain and total active reflection coefficient is presented to validate the performance of the multiple-input–multiple-output (MIMO) antenna. The isolation of the proposed MIMO antenna is 28 dB at 5.8 GHz and the envelope correlation equals 0.003. Owing to these good performances each antenna can operate almost independently. A good agreement is achieved between the simulated and the measured results.

This study presents the design of switching techniques for dual‐notched ultra‐wideband antenna. The dual band‐notched frequencies are achieved by using switched defected microstrip structure band stop filter inserted in the microstrip feed line and a switched meandered slot etched in the radiation patch. The switching reconfiguration is accomplished by combining the two ideal switches to introduce a notch filter response to prevent the interference to the primary users operating in the middle and upper WiMAX wireless local area network bands. The proposed structure has four modes by controlling the two switches on and off. The proposed antenna has good matched impedance from 2.5 to 12 GHz with two notched bands from 3.3 to 3.8 GHz (middle WiMAX applications) and from 5.1 to 5.9 GHz (upper WiMAX applications). The antenna is fabricated and tested. Good agreement is achieved between the simulated and measured results.

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