Left-handed Transmission Line Sections Research Articles

A Broadband 3 dB Tandem Coupler Utilizing Right/Left Handed Transmission Line Sections

A new type of broadband 3 dB tandem coupler has been proposed featuring frequency characteristics of the resulting coupling similar to those of a classic 3 dB two-section asymmetric coupled-line directional coupler. The coupler is composed of two loosely coupled-line sections having electrical lengths close to quarter-wavelength connected by right-handed and left-handed transmission line sections. Theoretical analysis and design equations have been presented with an exemplary realization. Measurements of the manufactured tandem coupler operating at f0 = 1 GHz having wide operational bandwidth have been shown to validate the presented analysis.

Broadband magic-Ts with the use of coupled-line directional couplers and left-handed transmission line sections

The problem of broadband magic-T realization with the use of coupled-line directional couplers and left-handed LH transmission-line sections has been comprehensively investigated. Broadband amplitude characteristics of the proposed networks are ensured with the use of coupled-line couplers, whereas the required phase characteristics have been achieved by the appropriate selection of right- and left-handed transmission line sections. To analyze the properties of the proposed networks, a model of an ideal left-handed transmission line has been utilized. The presented concept has been verified by two designs of broadband magic-Ts operating in 2.5-3.5 GHz and 0.8-2.3 GHz, respectively. The obtained results proved that the proposed magic-T networks allows one to obtain broadband amplitude and phase responses together with its compact structure. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:513-521, 2014.

Bandwidth improvement of rat-race couplers having left-handed transmission-line sections

A novel broadband rat-race coupler has been investigated. The coupler utilizes an artificial left-handed transmission line section for broadband phase response realization. Moreover, a narrowband model of left-handed section has been shown to prove the couplers equivalent circuit at the center frequency. To broaden the operational bandwidth multisection quarter-wave transformers have been proposed. The exemplary rat-race coupler with two-section impedance transformers has been designed and manufactured. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:341-347, 2014.

A Compact Bandpass Filter Based on Right- and Left-Handed Transmission Line Sections

A new type of a compact second-order bandpass filter (BPF) with two transmission zeros based on transversal signal-interference technique is proposed in this letter. Unlike other transversal filters published, the proposed structure is composed of artificial right- and left-handed transmission lines, instead of traditional distributed transmission line sections. Such an approach is not only helpful in size reduction, but also promising for frequency-asymmetrical stopband performance achievement. Design equations and guidelines to adjust filter performance are provided in the letter. To validate the proposed design approach, a two-pole BPF was designed, fabricated using multilayer liquid crystal polymer (LCP) technology and measured.

Tunable microwave devices based on left/right-handed transmission line sections in multilayer implementation

Metamaterial transmission lines can be realized as a combination of right- and left-handed transmission line (TL) sections exhibiting positive and negative dispersion. This approach gives additional degrees of freedom for improving the performance of microwave devices. Artificial right- and left-handed sections, which are based on lumped-element unit cells consisting of inductance and capacitances (LC-cells), are used. This makes it possible to decrease dimensions of the devices drastically. Furthermore, using variable capacitors in LC-cells allows designing tunable devices. This paper presents the results of design, numerical simulation, and experimental investigation of a tunable rat-race ring and free-of-spurious response dual-band filter manufactured as integrated ceramic multilayer circuits based on low-temperature co-fired ceramics. Commercial semiconductor varactors have been used as tunable components.

Broadband digital phase shifter based on switchable right- and left-handed transmission line sections

A novel approach to design digital phase shifters with the operational bandwidth extended to one octave is presented. An original design of the broadband phase shifter based on switching between transmission lines (TLs) with positive and negative dispersions is considered. An artificial TL with the negative dispersion was implemented as a quasilumped-element coplanar structure using a multilayer technology. The simulated and measured performance of the 180/spl deg/ phase shifter is presented.