Gerard Siso

Application of Composite Right/Left Handed (CRLH) Transmission Lines based on Complementary Split Ring Resonators (CSRRs) to the Design of Dual-Band Microwave Components

In this letter, composite right/left handed transmission lines based on complementary split ring resonators are applied to the design of dual-band microwave components. Specifically, impedance inverters operative at two (arbitrary) different frequencies (one of them within the left-handed band and the other within the right-handed band) are designed and applied to the implementation of a dual-band branch line hybrid coupler. The characterization of this device reveals good performance and dual-band operation. The fabricated device is small, fully planar, and vias are not required.

Applications of Open Split Ring Resonators and Open Complementary Split Ring Resonators to the Synthesis of Artificial Transmission Lines and Microwave Passive Components

This paper is focused on the application of open split ring resonators (OSRRs) and their dual counterparts, open complementary split ring resonators (OCSRRs), to the synthesis of composite right/left-handed transmission lines, that is, artificial lines exhibiting backward wave propagation at low frequencies and forward wave propagation at high frequencies. Due to the small dimensions of these resonators, the resulting lines are very compact. Several artificial lines, with different electrical characteristics and topologies, are reported as illustrative examples. It is shown that these artificial lines can be applied to the synthesis of dual-band components and bandpass filters, and two prototype device examples are designed and fabricated in coplanar waveguide technology: a dual-band impedance inverter applied to a dual-band power divider, and an order-3 wide-band bandpass filter. Finally, it is also demonstrated that OSRRs and OCSRRs can be combined for the synthesis of band pass filters in microstrip technology. Since OSRRs and OCSRRs are described by means of series and shunt resonant tanks, respectively, and they are electrically small, their potential to the design of semi lumped planar microwave devices is very high.

Planar Multi-Band Microwave Components Based on the Generalized Composite Right/Left Handed Transmission Line Concept

This paper is focused on the design of generalized composite right/left handed (CRLH) transmission lines in a fully planar configuration, that is, without the use of surface-mount components. These artificial lines exhibit multiple, alternating backward and forward-transmission bands, and are therefore useful for the synthesis of multi-band microwave components. Specifically, a quad-band power splitter, a quad-band branch line hybrid coupler and a dual-bandpass filter, all of them based on fourth-order CRLH lines (i.e., lines exhibiting 2 left-handed and 2 right-handed bands alternating), are presented in this paper. The accurate circuit models, including parasitics, of the structures under consideration (based on electrically small planar resonators), as well as the detailed procedure for the synthesis of these lines using such circuit models, are given. It will be shown that satisfactory results in terms of performance and size can be obtained through the proposed approach, fully compatible with planar technology.

Recent Advances in Metamaterial Transmission Lines Based on Split Rings

This paper is focused on metamaterial transmission lines based on split rings. Specifically, the considered lines are those based on the hybrid approach, where complementary split ring resonators (CSRRs) are combined with series gaps and shunt inductive stubs, and those implemented by loading a host line with open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs). The dispersion characteristics and the characteristic impedance of such lines, essential for design purposes, are analyzed to the light of the lumped element equivalent circuit models of the lines. Finally, it is shown that hybrid lines are useful for the design of power splitters with filtering capability, and OSRR/OCSRR-loaded lines are of interest for the design of wideband bandpass filters. The achieved performances are satisfactory and device dimensions small.

Compact Rat-Race Hybrid Coupler Implemented Through Artificial Left Handed and Right Handed Lines

In this work, a rat-race hybrid coupler based on left handed (LH) and right handed (RH) lines implemented by means of complementary split rings resonators (CSRRs) is designed and fabricated for the first time. The three 90deg transmission lines of the conventional device are replaced by RH artificial lines consisting on the combination of a CSRR and a shunt connected stub; the 270deg line is substituted by a -90deg LH line, where a CSRR is combined with a series gap. The resulting device is three times smaller than the conventional rat-race, the artificial lines do not include lumped elements, and device performance is good. Since dispersion in the artificial lines forming the device can be tailored, excellent characteristics in terms of phase-balance are obtained. These artificial lines can be applied to other microwave components. Size reduction and performance improvement are the key issues.

Generalized Model for Multiband Metamaterial Transmission Lines

In this letter, a generalized circuit model valid for the description of composite right/left handed metamaterial transmission lines with an arbitrary number of bands is presented for the first time. The model is a T- or pi-circuit where the series branch is composed of parallel connected series resonators, and the shunt branch consists on series connected parallel resonant tanks. It is demonstrated that any arbitrary T- or pi-circuit exhibiting alternate left-handed and right-handed bands can be expressed in the form of the proposed circuit. This justifies the consideration of the circuit as a generalized model of multiband metamaterial transmission lines.

Dual-band Y-junction power dividers implemented through artificial lines based on complementary resonators

In this work, dual-band Y-junction power dividers based on impedance inverters with composite right/left handed (CRLH) characteristics are presented for the first time. The inverters are either implemented through complementary split ring resonators (CSRRs) or through complementary spiral resonators (CSRs). By using the left handed and right handed frequency bands of the inverters, the required phase shifts, −90° and +90°, at the respective operating frequencies, ƒ<inf>1</inf> and ƒ<inf>2</inf>, can be obtained, whereas the characteristic impedance can be set to the necessary value to achieve effective input matching (Z<inf>o</inf>=35.35Ω for a 1:2 power splitter). The main advantages of these devices are: (i) dual-band operation with arbitrary ƒ<inf>2</inf>/ƒ<inf>1</inf> ratio, due to the possibility of engineering the dispersion diagram of the impedance inverter; (ii) compact size, owing to the small electrical size of CSRRs or CSRs; and (iii) full compatibility with planar technology, since neither lumped elements nor vias are used. The reported examples are two dual-band Y-junction power dividers operative at the mobile GSM bands (ƒ<inf>1</inf>=0.9GHz, ƒ<inf>2</inf>=1.8GHz). The area occupied by the CSR- and CSRR-based divider is 0.11λ×0.09λ and 0.14λ×0.12λ, respectively (where λ is the guided wavelength at ƒ<inf>1</inf>) and their measured characteristics are good.

Dual-band rat race hybrid coupler implemented through artificial lines based on complementary split ring resonators

A dual-band rat race hybrid coupler based on artificial lines implemented by means of complementary split ring resonators (CSRRs) is presented for the first time. Contrary to other dual-band components (such as branch line hybrid couplers or power dividers) based on the composite right/left handed (CRLH) characteristics of CSRR-loaded lines, the present design approach is based on the diplexer action of pairs of artificial lines; one of them designed to exhibit right handed wave propagation and the other one left handed wave propagation at the lower and upper frequency bands, respectively. The fabricated device is slightly smaller than the conventional (mono-band) rat race hybrid coupler, and it exhibits good performance. Full compatibility with planar technology and arbitrariness of the operating frequencies are advantages of the approach.

Fully planar implementation of generalized composite right/left handed transmission lines for quad-band applications

In this work, generalized composite right/left handed (CRLH) transmission lines are implemented in a fully planar configuration in coplanar waveguide (CPW) technology. These artificial lines exhibit two left handed (or backward) transmission bands and two right handed (or forward) transmission bands alternating, and are therefore of interest for the synthesis of quad-band microwave components. The lines are implemented by loading a host CPW with open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs). Accurate circuit models of the different line elements, taking the parasitics into account, and the whole structure are experimentally validated. These lines are applied in this work to the design of a quad-band power divider operative at the GSM (900MHz and 1800MHz) and GPS (1176.45 MHz and 1575.42 MHz) frequency bands. The main innovative aspect of this contribution is the implementation of the reported quad-band structure in planar technology, without the presence of lumped components. This is also the first time that OSRRs and OCSRRs are combined for the synthesis of a quad-band structure.

Compact Rat-race Hybrid Based on Complementary Split Rings Resonators

In this work, the application of Complementary Split Rings Resonators (CSRRs) to the design of a rat-race hybrid in microstrip technology is analyzed. The use of a left-handed (LH) cell composed by a CSRR etched in the ground plane and series capacitive gap reduces the length of the required 270 - line by a factor of 5. Thanks to this length reduction, the area of the flnal prototype is 4 times smaller than the conventional distributed design. The measured results show satisfactory behavior in the frequency of interest.