Novel Wideband Transition Between Coplanar Waveguide and Microstrip Line

A novel wideband vertical transition for connecting the coplanar waveguide (CPW) to the microstrip line is proposed. This transition can be very useful for millimeter-wave packaging and vertical interconnects. It is multilayered, partly tapered, and consists of only one via interconnect. Two different transitions are designed. The first transition allows connectivity of a CPW with Zc - 50 Ω to a microstrip line with Zc = 16 Ω with a bandwidth of 10-60 GHz. The second transition has the same characteristic impedance, Zc - 50 Ω, at the two ports. In this case, the operating frequency is from 40 MHz to 60 GHz. The return losses of both transitions are generally lower than-10 dB over their indicated frequency ranges, while the maximum measured insertion losses are 1.8 and 2.4 dB for the first and second transition, respectively. To extract the S-parameters of the transitions, a new thru-line technique, based on the standard thru-reflect-line two-tier calibration is introduced. Simulation and experimental results, showing good agreement, are presented and discussed. © 2010 IEEE

Analysis and design of a new reflection-type 360° phase shifter with combined switch and varactor

Analysis and design of a new 360° reflection type phase shifter is proposed. The new phase shifter uses a switch and one varactor device per reflective load. Equations for the analysis and design of the new phase shifter are presented. A 2.5 GHz phase shifter is fabricated using a varactor diode and a PIN diode per load. © 2010 Wiley Periodicals, Inc

Meander line millimetre-wave liquid crystal based phase shifter

A liquid crystal (LC) based inverted microstrip meander line phase shifter is presented. The control of phase shift is achieved through use of an external electric field. To facilitate on-wafer measurements and the application of the electric field to the LC, a specially developed transition from the inverted microstrip line to the CPW is used. The performance of the proposed meander line phase shifter is tested using two LC mixtures: first, the standard LC mixture, commonly referred to as E7, while the second mixture is known as MDA-00-3506. A differential phase shift of 202° is achieved with the phase shifter using E7 and 270° using MDA-00-3506 at 50GHz for a 50mm-long microstrip line meandered into a length of 7.67mm. The results are discussed. © 2010 The Institution of Engineering and Technology

Combined Low Frequency and Third Harmonic Injection in Power Amplifier Linearization

Simultaneous injection of the difference frequency and triple frequency signals into the main RF amplifier (alongside the fundamental frequency signals) offers an independent improvement of IM3 and IM5. This advantage is not achievable by other reported techniques. Mathematical analysis of this new power amplifier linearization is resented in order to establish the potential of the proposed technique. The analysis shows that the injection of the difference frequency signal reduces IM3, though it may influence IM5. However, any deterioration of IM5 improves significantly as a result of the injection of the triple frequency signals without disturbing the advantage gained by the difference frequency injection on the levels of IM3. For the validation of the theoretical results, an experimental amplifier system operating at 880 MHz was built. The two-tone measurement confirmed the theoretical predictions.© 2006 IEEE

Tuneable Dielectric and Optical Characteristics of Tailor-Made Inorganic Electro-Chromic Materials

Abstract Electro-chromic materials (EC) are a new class of electronically reconfigurable thin films that have the ability to reversibly change optical properties by electric charge insertion/extraction. Since their discovery by Deb, they have been employed in applications related to display technology, such as smart windows and mirrors and active optical filters. In this sense, a variety of studies related to the tuneable optical characteristics of EC materials have recently been reported, however, their microwave tuneable dielectric characteristics have been left somewhat unexplored. In 2016 Bulja showed that dc bias voltage induced modulation of the optical characteristics of an inorganic Conductor/WO3/LiNbO3/NiO/Conductor EC cell isaccompanied by the modulation of its high frequency (1–20 GHz) dielectric characteristics. In general, according to the state of the art, cells of different material compositions are needed to produce devices of tailor made characteristics. Here, we report the discovery that the microwave dielectric and the optical characteristics of an EC cell can be engineered to suit a variety of applications without changing their material composition. The obtained results indicate the potential for producing novel, tuneable and tailor-engineered materials that can be used to create next generation agile microwave-optical devices

Accurate Modeling for Wideband Characterization of Nematic Liquid Crystals for Microwave Applications

Liquid crystals are attractive materials for use in millimeter- wave band communications devices due to their large birefringence and reconfigurability. However, characterizing these materials is challenging at these frequencies. This work describes the modeling tools that have been developed for the accurate analysis of the liquid crystal orientation and of the wave propagation through the inhomogeneous and anisotropic liquid crystal layer. It also shows how the modeling has been used in conjunction with experimental measurement to characterize liquid crystal materials over a wide frequency range. © 2009 IEEE

60 GHz Reflection Type Phase Shifter based on liquid crystal

For the first time, a compact 60 GHz band phase shifter incorporating liquid crystal (LC) is presented. Based on the Reflection Type Phase Shifter (RTPS) structure, it comprises a 3-dB coupler and tunable reflective loads formed on a nematic LC substrate. The LC used to form the substrate is known as E7. Biasing of the LC is achieved using an external electric field, allowing for the control of the reactance of the reflective loads. To facilitate on-wafer measurements and the application of the electric field to the LC, a transition from the microstrip line to the CPW is used. Preliminary measurement results for this RTPS show a differential phase shift of over 130 degrees, a figure of merit of 11.4°/dB and return losses better than -10dB at 61 GHz. © 2010 IEEE

Planar transmission line method for measurement of dielectric constants of liquid crystals in 60 GHz band

Recent characterizations of liquid crystal (LC) materials invariably use magnetic field for biasing LC. In this paper a transmission line method is proposed for the characterization of the dielectric properties of LC in the 60 GHz band, using electric field bias. In this method a balanced strip line is used to accommodate the LC sample. To facilitate the application of the electric field to the LC and to ease the measurement of the scattering parameters, a unique transition from the balanced strip line to the finite ground coplanar waveguide (FGCPW) is developed. The LC investigated in this paper is the E7 mixture. ©2009 IEEE