Browsing by Subject "Microwave devices"

Now showing 1 - 6 of 6

Open Access
Low-frequency time-domain characterization for fast and reliable evaluation of microwave transistor performance
(IEEE, 2016) Bosi G.; Raffo A.; Vadalà V.; Trevisan F.; Vannini G.; Cengiz, Ömer; Şen, Özlem; Özbay, Ekmel
In this paper, we introduce the use of the low-frequency characterization of electron devices as an accurate and economical way to fast gather consistent data about the electron device performance at microwaves in the evaluation phase of new components, technologies and processes. © 2016 European Microwave Association.
Open Access
Low-voltage small-size double-arm MEMS actuator
(2009) Bıyıklı, Necmi; Damgaci, Y.; Cetiner, B.A.
The fabrication and characterisation of a double-arm cantilever-type metallic DC-contact MEMS actuator with low pull-down voltage are reported. Bi-layer TiW cantilevers with an internal stress gradient were fabricated using a microwave-compatible fabrication process. Owing to its small size, cantilever length (L=5-50m) and width (W=2-40m), i.e. ∼10-100 times smaller in lateral dimensions than a standard MEMS actuator, this actuator showed actuation voltages lower than 10 V. RF measurements of the 10m-wide actuators yielded an average insertion loss less than 1dB and isolation higher than 40dB up to 25GHz. The developed actuator is well suited for integration in reconfigurable microwave circuits and systems such as reconfigurable antennas and arrays. © 2009 The Institution of Engineering and Technology.
Open Access
Microwave resonators enhanced with 3D liquid-metal electrodes for microparticle sensing in microfluidic applications
(Institute of Electrical and Electronics Engineers , 2023-11-22) Alataş, Yağmur Ceren; Tefek, Uzay; Sari, B.; Hanay, Mehmet Selim
In electrical sensing applications, achieving a uniform electric field at the sensing region is required to eliminate the compounding effect of particle location on the signal magnitude. To generate a uniform electric field in a microfluidic platform, 3D electrodes based on conductive electrolyte liquids have been developed before, where the ionic conductivity of the electrolyte was sufficient for impedance measurements at low frequencies (typically lower than 50 MHz). However, electrolyte liquids cannot be used as electrodes at microwave frequencies (>1 GHz) due to the low mobility of ions. Here, we used Galinstan, a room-temperature liquid metal, to microfabricate 3D liquid electrodes connected to a microwave resonator — and all integrated within a microfluidic system. By generating a highly uniform electric field, a mixture of 20 μm and 30 μm diameter polystyrene particles were measured and analyzed without any calibration for particle position. The results demonstrate the utility of liquid electrodes in enhancing the electrical characteristics of microwave resonant sensors.
Open Access
A new method for the steady-state analysis of periodically excited nonlinear circuits
(Institute of Electrical and Electronics Engineers, 1996-12) Celik, M.; Atalar, Abdullah; Tan, M. A.
We propose a new method for the steady state analysis of periodically excited nonlinear microwave circuits. It is a modified and more efficient form of Newton-Raphson iteration based harmonic balance (HB) technique. It solves the convergence problems of the HB technique at high drive levels. The proposed method makes use of the parametric dependence of the circuit responses on the excitation level. It first computes the derivatives of the complex amplitudes of the harmonics with respect to the excitation level efficiently and then finds the Pade approximants for the amplitudes of the harmonics using these derivatives.
Open Access
Resonant cavity-enhanced detectors embedded in photonic crystals
(IEEE, 1996) Temelkuran, Burak; Özbay, Ekmel
Summary form only given. We demonstrate the resonant-cavity-enhanced effect by placing microwave detectors in a layer-by-layer photonic crystal. We used the output of a network analyzer as the microwave source, and fed the output to a horn antenna to obtain EM waves. The crystal was then replaced in the beam-path of the EM wave, and the electric field inside the cavity was measured by a probe that consisted of a monopole antenna. The output of the antenna was measured by use of two different techniques: network analyzer and microwave detector within the cavity. The first cavity structure was similar to a one-dimensional Fabry-Perot resonator made of two mirrors separated by a distance.
Open Access
Three-dimensional electrode integration with microwave sensors for precise microparticle detection in microfluidics
(IEEE, 2024-05-15) Alataş, Yağmur Ceren; Tefek, Uzay; Küçükoğlu, Berk; Bardakçı, Naz; Salehin, Sayedus; Hanay, M. Selim
Microwave sensors integrated with microfluidic platforms can provide the size and permittivity of single cells and microparticles. Among the microwave sensor topologies, the planar arrangement of electrodes is a popular choice owing to the ease of fabrication. Unfortunately, planar electrodes generate a nonuniform electric field, which causes the responsivity of the sensor to depend on the vertical position of a microparticle in the microfluidic channel. To overcome this problem, we fabricated 3-D electrodes at the coplanar sensing region of an underlying microwave resonator. The 3-D electrodes are based on SU8 polymer, which is then metallized by sputter coating. With this system, we readily characterized a mixture composed of 12- and 20 $\mu \text{m}$ polystyrene particles and demonstrated separation without any position-related calibration. The ratio of the electronic response of the two particle types is approximately equal to the ratio of the particle volumes, which indicates the generation of a uniform electric field at the sensing region. This work obviates the need for using multiple coplanar electrodes and extensive processing of the data for the calibration of particle height in a microfluidic channel: as such, it enables the fabrication of more sophisticated microwave resonators for environmental and biological applications.