Design Guidelines for the Excitation of Characteristic Modes in Slotted Planar Structures

Abstract

Abstract-This paper provides some design guidelines for the excitation of broadband slotted planar antennas, addressing key issues such as coupling, symmetries and multiple feeding. The Theory of Characteristic Modes is used to identify the collection of current modes that exists on these structures, dealing to a valuable understanding of the radiating mechanisms and allowing a more controlled design process. Modal analysis of a circular aperture cut on a finite square ground plane is presented in order to demonstrate that an optimum choice of the feeding mechanism can be made according to the current distribution of the desired modes. Based on the information yielded by this modal analysis, a capacitive-coupled dual-feed circular aperture antenna is presented. This antenna takes advantage of the symmetries of the characteristic currents by making use of multiple feeding, in order to excite only some particular modes. Usage of commonly-fed and differentially-fed configurations enables an increased control of the excitation of modes in the structure. Characteristic modes analysis of the antenna including the feeding structures is presented, showing the influence of the feeding lines in the performance of this type of antennas. A prototype of the antenna has been fabricated and measured. Simulated and measured results are presented, being in good agreement.

Analysis and Design of a Metamaterial Lens Antenna Using the Theory of Characteristic Modes

“…In addition to the first applications of the TCM reviewed in [13], this theory has been recently used to analyze the bandwidth of a 2 × 2 bowtie array with a metasurface [14], design electrically small unmanned aerial vehicle (UAV) antennas [15], design and analyze slotted planar structures [16], or study some canonical structures such as spheres or cylinders [17]. Moreover, a single-layer metal lens formed by a central circular metallic ring surrounded by a set of eight metallic rings was analyzed using the TCM in [18], a wideband low-profile metasurface antenna was modeled and optimized using characteristic modes in [19], and a low-profile lens using metallic cylinders was investigated in [20] using the TCM.…”

Analysis of slot-based radiators using TCM and its application in MIMO antennas

“…To investigate this issue, we consider a ground plane size of 80 × 80 mm 2 following that in Ref. to have a fair comparison. The antenna was simulated in CST to get its CM.…”

“…TCM was applied on the analysis of various different types of antennas such as wire antennas, handset antennas, printed MIMO antennas, and slot antennas . In Ref.…”

“…In Refs. , it was claimed that the slot mode did not appear independently, but a new set of modes that are the combination of the slot and chassis modes appeared coherently. In all the literature investigated and to the best of the author's knowledge, no one investigated whether this new mode is actually a mode due to the slot or is a modified chassis mode.…”

“…TCM was applied on the analysis of various different types of antennas such as wire antennas, 21 handset antennas, 22 printed MIMO antennas, [23][24][25] and slot antennas. [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42] In Ref. 43, it was shown that designs made with TCM are more robust under real-environment scenarios as compared to designs made with empirical methods.…”