Abstract. In this paper, a reconfigurable antenna with capability to operate in the ultrawideband (UWB) mode from 2.85 to 14.4 GHz with switchable notch bands of 3.

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This paper describes a new configuration of frequency-selective structure (FSS) structures to reduce mutual coupling between the radiating elements. Also, the antenna performance before and after the implementation of FSS have been investigated. The proposed configuration provides an improvement in mutual coupling by 14 dB (measured value) with a reduced edge-to-edge spacing of 23 mm. The reduction of mutual coupling between antenna elements is interesting in the electromagnetic and antenna community. The use of electromagnetic band-gap structures constructed by microstrip technology is a way to appease the mutual coupling problem. Periodic structures such as FSS can help in the reduction of mutual coupling using their ability of suppressing surface waves propagation in a given frequency range. The goal of this present study is to use it in patch antenna arrays, keeping both the element separation smaller than λ0for grating lobes evasion and the patch antenna size large enough to have good antenna directivity. The results showed that the proposed configuration eliminates disadvantages of similar structures presented in the previous works.

In this paper, a switchable antenna with capability to operate in ultrawideband (UWB) frequency from 3 to 10.7 GHz with two switchable notch bands of 3.3–3.7 and 3.7–4.2 GHz, is presented for cognitive radio (CR) and multiband orthogonal frequency-division multiplexing (MB-OFDM) applications. The proposed antenna has a simple structure and compact size of 17 × 24 mm2. The antenna in the UWB characteristics is obtained using a circular radiator patch with an embedded T-slot on the patch and a rectangular parasitic element that is attached to the patch. The reconfigurability is also achieved by two L-shaped parasitic elements placed in the left and right of the patch that two ideal switches is inserted over the these elements and the circular patch. The function of the antenna can be changed by tuning status of the switches that make the notch bands in application frequencies. The measurement and simulation results show that the antenna has good characteristics for CR application and MB-OFDM, where the UWB antenna is required for spectrum sensing and the switchable band rejection antenna is used for reconfigurable operation.

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