In this paper, the theoretical foundations of the equivalence between waveguide propagation below cutoff and artificial plasmas are carefully analyzed through the derivation of the propagation constants of normal modes in waveguides filled with anisotropic plasmas. The equivalence between waveguide and dielectric plasma proposed by Marqués et al., which is valid for evanescent TE modes, has a dual counterpart for magnetic plasmas and evanescent TM modes. This new equivalence states that a negative magnetic permeability medium can be simulated by means of TM modes below their cutoff frequencies. The need of an anisotropic filling of the waveguide for the equivalence between plasmas and evanescent modes is also highlighted. To exemplify the applicability of this new equivalence, a structure that implements a double-negative medium has been proposed. Full-wave simulations of the proposed structure and measurements from an experimental setup are presented, both of which corroborate the new equivalence's validity.Index Terms-Backward waves, electric plasmas, evanescent modes, magnetic plasmas, metamaterials, negative permeability, negative permittivity, periodic structures.
Interdigital capacitors (IDCs) are convenient capacitance devices in microstrip circuits, even if only low capacitance values can be achieved. Nevertheless, undesired resonances degrade their performance when frequency increases. Short circuits across the end of alternate fingers of the IDC improve its high frequency response by eliminating that drawback. Simulated and measured results are presented.Index Terms-Interdigital capacitor (IDC), microwave passive circuits, wire bonded interdigital capacitor (WBIDC), wire bonding.
An enhanced composite right/left-handed (CRLH) transmission line (TL) is presented in this letter. This TL, designed in microstrip technology, is implemented by means of a new improved interdigital capacitor (IDC), the so-called wire bonded IDC (WBIDC). The use of the WBIDC broadens the frequency band where the CRLH TL can be considered as a TL. A conventional 70-CRLH TL (using IDCs) has been compared, by full-wave simulation and measurements, with its enhanced counterpart (using WBIDCs). In addition, this enhanced CRLH TL has been used to design a CRLH diplexer which presents several advantages over standard CRLH coupled lines (using IDCs). The diplexer response has been verified by means of a full-wave electromagnetic solver.Index Terms-Composite right/left-handed (CRLH) metamaterials, microwave passive circuits, wire bonded interdigital capacitor (WBIDC).
Abstract-This paper presents a six-section multi-layer asymmetric 10 dB directional coupler based on offset broadside coupled striplines, using Low Temperature Co-fired Ceramic (LTCC) technology, which operates over a decade bandwidth from 1.8 to 18 GHz. It features high performance transitions between the external signal layer and the buried signal layers, as well as a novel mixed first section to solve the limitations of the coupler access bends. A prototype was manufactured that exhibits a return loss of better than 15 dB, isolation of better than 23 dB and a high coupling accuracy of 10.3±0.6 dB over the 1.8-18 GHz band. This design outperforms previously reported results in terms of bandwidth and shows excellent potential for microwave measurement applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.