In this paper, an antenna with reconfigurable band notches, for cognitive radio applications, is proposed. The antenna can be operated as ultra wideband, and is reconfigurable in terms of the ability to select a notched band in the SRR resonant frequency. The reconfigurable band notches are induced using a band-stop filter based on split-ring resonators (SRRs), and are controlled using electronic switches mounted over the SRRs. For this sake, the design of the band-stop filter is proposed. A prototype of filter is fabricated and measured. The incorporation of a band-stop filter, into a wideband antenna, is then looked into. The proposed antenna is designed and simulated using Ansoft HFSS. A prototype of the antenna is fabricated and measured. A good analogy between simulated and measured results is obtained.
In this paper, a design of very compact microstrip bandstop filters based on complementary split ring resonators (CSRRs) is proposed. Two techniques of metamaterial miniaturization are used to optimize the physical and electrical size of the CSRR. The bandstop filter is produced by an array of miniaturized loaded CSRRs etched on the center line of a microstrip. The size of the proposed filter, is as small as 0.58 cm2, and its electrical length is very small with only 0.08 λ0), compared to a conventional bandstop filter, a miniaturization of a factor 5 while the bandstop performance is maintained. A very good agreement obtained between the measurement and the simulation results.
IntroductionRecently, a whole new area of research emerged from the design and the characterization of materials having intrinsic properties not present in the nature [1,2]. Among those artificial media, it is possible to distinguish the double negative metamaterial, made of periodically spaced sub-wavelength metalodielectric cells, presenting simultaneously a negative permeability and a negative permittivity. The development of planar cells opened the field for a range of applications in the microwave domain, especially for the antenna design. In this paper we present the design of a new metamaterial cell which is double negative in permeability and in permittivity. It is inspired on a structure firstly introduced by O'Brien in the optical domain at infrared frequencies [3], and is composed of two symmetrical half rings backed by a wire (SHR-W). In the area of antenna design, metamaterials can be used as a lens in order to perform the focusing of the waves [4,5]. With the proposed metamaterial cell, we show its interest for such an antenna focusing lens applications.
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