Carlos Camacho-Peñalosa

High-gain active composite right/left-handed leaky-wave antenna

A novel high-gain active composite right/left-handed (CRLH) metamaterial leaky-wave antenna (LWA) is presented. This antenna, which is designed to operate at broadside, is constituted by passive CRLH leaky-wave sections interconnected by amplifiers, which regenerate the power progressively leaked out of the structure in the radiation process in order to increase the effective aperture of the antenna and thereby its gain. The gain is further enhanced by a matching regeneration effect induced by the quasi-unilateral nature of the amplifiers. Both the cases of quasi-uniform and binomial field distributions, corresponding to maximum directivity and minimum side-lobe level, respectively, have been described. An active LWA prototype is demonstrated in transmission mode with a gain enhancement of 8.9 dB compared to its passive counterpart. The proposed antenna can attain an arbitrarily high gain by simple increase of the length of the structure, without penalty in terms of return loss and without requiring a complicated feeding network like conventional array antennas

Dual-band, single CPW port, planar-slot antenna

A dual-band planar-slot antenna that operates through a single coplanar waveguide (CPW) port in two 10% wide-frequency bands, one octave apart is presented. An input T-match circuit is used to match the antenna in both bands, without increasing its size and keeping the CPW feed advantages. A case antenna covering the two Global System for Mobile communications bands (0.88-0.96 GHz and 1.71-1.88 GHz) and the Digital Enhanced Cordless Telecommunications band (1.88-1.9 GHz) has been designed, built, and measured, to demonstrate the technique. A proprietary program, based on the method of moments, has been used to analyze and optimize the antenna.

Simulation of negative permittivity and negative permeability by means of evanescent waveguide Modes-theory and experiment

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 Marquees 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 equivalences validity.

Wire bonded interdigital capacitor

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.

Vertical microstrip transition for multilayer microwave circuits with decoupled passive and active layers

A novel broadband (including dc) microstrip-to-microstrip vertical transition for multilayer microwave circuits is proposed. This transition solves the problem of the discontinuity typically appearing in via hole transitions between two microstrip transmission lines in different layers. An analogy existing between this transition and a rectangular coaxial line is discussed. A parametric study alongside with the experimental results of the transition are presented. Reduction of local oscillator to radio frequency leakage in a mixer with this transition is demonstrated

Analytical model of the wire-bonded interdigital capacitor

The wire-bonded interdigital capacitor (WBIDC) is an interdigital capacitor with short circuits across the end of alternate fingers that result in an improved frequency response. This paper presents the analytical and circuital models of the WBIDC, which are useful to design and to incorporate into an electromagnetic or circuit analysis computer-aided design program. Design equations of the WBIDC are also presented. The analytical model and design equations have been validated with numerical analysis and experimental work.

Experimental performance of a meta-distributed amplifier

Meta-distributed amplifiers (MDAs) constitute a novel class of distributed amplifiers based on the active coupling of two composite-right/left handed transmission lines, and can provide dual-band amplification at two different physical ports. In this contribution, the dual-band gain and noise performance of such active distributed circuits is experimentally demonstrated for the first time using a lumped element-based implementation. Obtained experimental results suggest that the performance of such MDAs can be similar to that of conventional distributed amplifiers as far as gain and noise figure are concerned, but with the added advantage of dual-band amplification.

Composite Right/Left-Handed Transmission Line With Wire Bonded Interdigital Capacitor

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-Omega 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

Lattice Equivalent Circuits of Transmission-Line and Coupled-Line Sections

A lattice network with branches made up of open- and short-circuited transmission-line sections is proposed as an equivalent circuit for a wide range of so-called coupled-line filter sections. The proposed lattice equivalent circuits have proven to be an advantageous alternative to the equivalent circuits found in the technical literature (when available) as they are exact, useful in wide frequency bands, and take into account the different phase velocities of even and odd modes.

DERIVATION AND GENERAL PROPERTIES OF ARTIFICIAL LOSSLESS BALANCED COMPOSITE RIGHT/LEFT-HANDED TRANSMISSION LINES OF ARBITRARY ORDER

A circuit theory-based approach for systematically deriving all possible lossless balanced composite right/left-handed transmission lines is described. To illustrate the usefulness of the proposed approach, novel artiflcial transmission line unit-cells with tri- and quad-band behaviour are proposed. It is shown that the number of right-handed or left-handed frequency bands exhibited by such transmission lines is determined by the order of its unit-cell. It is explained why artiflcial lossless balanced transmission lines exhibit a stop-band around each pole of their associated continuous transmission line that can not be closed up. Since this approach allows for the systematic derivation of such transmission line unit-cells of arbitrary order, multi-band components based on metamaterial transmission lines are envisaged.