Tunable Dual-Band Microwave Devices based on a Combination of Left/Right-Handed Transmission Lines

Abstract

Metamaterial transmission lines can be realized as a combination of transmission line sections with positive and negative dispersion. Such lines, which are also known as right-and left-handed transmission lines, exhibit different dispersion characteristics. Compared to homogeneous networks, the use of cascaded line sections gives additional degrees of freedom for improving the performance of microwave devices. For the design process, LC-equivalents of the right-and left-handed transmission line sections are used. This facilitates the consideration of tunable capacitors, e.g., varactor diodes, to provide frequency tuning of the devices. At the same time, the geometrical dimensions of the devices can be drastically reduced. This paper presents the results of simulation and experimental investigation of a miniature rat-race-ring and a dual-band filter free of spurious response, both manufactured as fully-integrated ceramic multilayer modules based on Low-Temperature Co-fired Ceramics. The design of tunable versions of these devices is also discussed.

Multi-band and tunable multi-band microwave resonators and filters based on cascaded left/right-handed transmission line sections

“…Similarly, RH TL sections can also be composed of lumped elements, leading to drastic reductions of dimensions. Using a combination of natural or artificial RH TLs and artificial LH TLs makes it possible, for instance, to design resonators and filters with a strongly suppressed response to spurious frequencies [9]- [13]. The rejection results from the nonlinear dispersion and from the finite cut-off frequency for artificial transmission lines.…”

High-Isolation and Wide-Band 180º Hybrids Based on Electronically Tunable Lumped-Element Filters

“…Compared to state-of-the-art configurations [9,10], the volume reduction is more than 70% in compact version, and 85% in ultracompact all-lumped version, both cases with less number of lumped components and only two varactors, both of the same model. The ultra-compact hybrid is the first all-lumped configurable 180 • hybrid that the authors know.…”

“…The classical approaches of lumped-element 180 • hybrids [5][6][7]12] type stop band configuration were possible, but low order filters are preferred because of their simplicity when adjustable filters are used to tune the characteristics on frequency [9,10]. This approach gives a minimum 3-varactor hybrid because all 3 LPF-s are converted to tuneable filters substituting the capacitors by varactors.…”

“…It is important to remark that improving the state-of-theart solutions [9,10], in this case, both varactors could be the same model. Schematic diagrams of both hybrids and the results of the quasirealistic simulations are presented in Figures 3 and 4.…”

“…On the other hand, some investigations have been carried out in recent years on tunable devices, based on metamaterial transmission lines [4,9,10], which indicate feasible work of this kind of configurable devices. This article focuses on this line of tunable devices, delving into the very high isolation property, necessary for the use of designed hybrids on the single balanced mixers (SBM) of the typical DSBM (Double Side Band Modulator) or SSBM (Single Side Band Modulator) structures, in order to achieve a high rejection of the LO.…”