Damien Passerieux

Full 3-D Printed Microwave Termination: A Simple and Low-Cost Solution

This paper describes the realization and characterization of microwave 3-D printed loads in rectangular waveguide technology. Several commercial materials were characterized at X-band (8-12 GHz). Their dielectric properties were extracted through the use of a cavity-perturbation method and a transmission/reflection rectangular waveguide method. A lossy carbon-loaded Acrylonitrile Butadiene Styrene (ABS) polymer was selected to realize a matched load between 8 and 12 GHz. Two different types of terminations were realized by fused deposition modeling: a hybrid 3-D printed termination (metallic waveguide + pyramidal polymer absorber + metallic short circuit) and a full 3-D printed termination (self-consistent matched load). Voltage standing wave ratio of less than 1.075 and 1.025 were measured over X-band for the hybrid and full 3-D printed terminations, respectively. Power behavior of the full 3-D printed termination was investigated. A very linear evolution of reflected power as a function of incident power amplitude was observed at 10 GHz up to 11.5 W. These 3-D printed devices appear as a very low cost solution for the realization of microwave matched loads in rectangular waveguide technology.

Intercomparison of Permittivity Measurement Techniques for Ferroelectric Thin Layers

The dielectric properties of a KTa0.65Nb0.35O3 (KTN) ferroelectric composition for a submicronic thin layer were measured in the microwave domain using different electromagnetic characterization methods. Complementary experimental techniques (broadband methods versus resonant techniques, waveguide versus transmission line) and complementary data processing procedures (quasi-static theoretical approaches versus full-wave analysis) were selected to investigate the best way to characterize ferroelectric thin films. The measured data obtained from the cylindrical resonant cavity method, the experimental method that showed the least sources of uncertainty, were taken as reference values for comparisons with results obtained using broadband techniques. The error analysis on the methods used is discussed with regard to the respective domains of validity for each method; this enabled us to identify the best experimental approach for obtaining an accurate determination of the microwave dielectric properties of ferroelectric thin layers.

Reconfigurable bandpass filter based on split ring resonators and vanadium dioxide (VO 2 ) microwave switches

In this paper, we present the design, fabrication and characterization of the first tunable bandpass filter that combines split ring resonators (SRRs) and vanadium dioxide (VO2)-based microwave switches. The device consists on a pair of coupled SRRs, feed by means of tapped microstrip lines, that can be connected to metallic patches by electronically activating the VO2-based switches. Through the fast and reversible Semiconductor-to- Metal Transition (SMT) of the VO2 thin films, the electrical characteristics of the SRRs are modified so that their resonance frequency, and as a result the central frequency of the bandpass filter can be electrically tuned. The fabricated filter, designed to operate in the X-band, exhibits a tuning range of nearly 10% where its electrical characteristics (bandwidth, insertion losses, etc.) are roughly preserved.

Quasi-Elliptic and Chebyshev Compact LTCC Multi-Pole Filters Functioning in the Submillimetric Wave Region at 150 GHz

This paper proposes, for the first time to the best of our knowledge, two challenging LTCC multi-pole bandpass filters operating at 150 GHz for radioastronomy applications. Low-temperature co-fired ceramic (LTCC) technology is employed to realize these filters because it assures the high precision and compactness needed at this high frequency. The two filters are optimized by 3-D electromagnetic simulations and are validated by experimental results. Different positive and negative couplings, which are achieved by different coupling apertures, are studied. The five-pole Chebyshev filter has 8.4 dB of insertion loss in a 1.31% fractional bandwidth for 6.7 mm 2.45 mm lateral dimensions. The fourpole quasi-elliptic filter is conceived to decrease insertion loss by decreasing the number of resonant cavities while conserving the same selectivity by introducing two transmission zeros around the passband. Beside 5.5 dB of insertion loss, this filter occupies a more compact circuit area (3.32 mm 2.37 mm) and insures a very good spurious free region (16 GHz) around 150 GHz. Experimental results are in good agreement with the theoretical ones and validate the use of LTCC technology at such high frequencies over 100 GHz.

Electromagnetic properties of polycrystalline diamond from 35 K to room temperature and microwave to terahertz frequencies

Dielectric resonators are key components for many microwave and millimeter wave applications, including high-Q filters and frequency-determining elements for precision frequency synthesis. These often depend on the quality of the dielectric material. The commonly used material for building the best cryogenic microwave oscillators is sapphire. However, sapphire is becoming a limiting factor for higher frequency designs. It is, then, important to find new candidates that can fulfill the requirements for millimeter wave low noise oscillators at room and cryogenic temperatures. These clocks are used as a reference in many fields, such as modern telecommunication systems, radio astronomy (very-long-baseline interferometry), and precision measurements at the quantum limit. High resolution measurements were taken of the temperature-dependence of the electromagnetic properties of a polycrystalline diamond disk at temperatures between 35 and 330 K at microwave to submillimeter wave frequencies. The cryogenic measu...

Out-of-plane and inline RF switches based on Ge 2 Sb 2 Te 5 phase-change material

We present the fabrication and characterization of novel RF switches based on Ge2Sb2Te5 (GST) phase change material. Such ohmic devices show non-volatile switching with resistivity changes up to 105 as the material is transforming between the amorphous and the crystalline state by either applying a voltage pulse or direct heating. We investigated the RF properties and power handling of such devices in two configurations: out-of-plane (GST material between two electrodes) and inline switches. For a directly heated 10-μm length inline switch we measured an on-state resistance of 7 Ω, and an off-state capacitance and resistance of 13.7 fF and 6.47 MΩ, respectively, resulting in a cut-off frequency of ~1.6 THz.

150 GHz Band-Pass Filter Using LTCC Technology

A low temperature co-fired ceramic 150 GHz bandpass filter is, for the first time, designed and manufactured. Experimental electric performances are encouraging and validate the use of LTCC technology at submillimeter wave range. A Chebyshev 2-pole bandpass filter is achieved, with 1.6% bandwidth and 4.6 dB insertion loss. The unloaded quality factor is found to be 290.

Microwave dielectric properties of BNT-BT0.08 thin films prepared by sol-gel technique

We report for the first time the microwave characterization of 0.92(Bi0.5Na0.5)TiO3-0.08BaTiO3 (BNT–BT0.08) ferroelectric thin films fabricated by the sol-gel method and integrated in both planar and out-of-plane tunable capacitors for agile high-frequency applications and particularly on the WiFi frequency band from 2.4 GHz to 2.49 GHz. The permittivity and loss tangent of the realized BNT-BT0.08 layers have been first measured by a resonant cavity method working at 12.5 GHz. Then, we integrated the ferroelectric material in planar inter-digitated capacitors (IDC) and in out-of-plane metal-insulator-metal (MIM) devices and investigated their specific properties (dielectric tunability and losses) on the whole 100 MHz–15 GHz frequency domain. The 3D finite-elements electromagnetic simulations of the IDC capacitances are fitting very well with their measured responses and confirm the dielectric properties determined with the cavity method. While IDCs are not exhibiting an optimal tunability, the MIM capacit...

Pulsed power operation of power limiters integrating a phase transition material

We present the operation of microwave power limiters based on reversible phase transition of vanadium dioxide thin films integrated on coplanar waveguides submitted to incident pulsed peak power at 10 GHz. During the pulse on-time, the fabricated devices can be reversibly driven by the incident signal from a high transmission state to a low-transmission level on a relatively short timescale (response times as low as 4 μs for incident peak powers of 35 dBm). The broadband operation and the simplicity of fabrication and integration of these devices, their potential for faster response times, make them attractive as protective devices against continuous or transient RF power.

Quasi-elliptic 150 GHz highly selective LTCC filter

In this paper, and for the first time to the best of our knowledge, a very challenging 4-pole quasi-elliptic filter in the submillimetric wave range is studied and fabricated by the LTCC technology. The proposed 4-pole filter, centered at 150 GHz with 2 GHz band pass, is described and the coupling apertures used to provide the required positive and negative couplings are studied. The measured response is in very good agreement with the predicted behavior with a central frequency of 149.7 GHz (0.2% variation) and a 2.02 GHz band pass. The obtained manufactured filter is compact in size (3.32 mm x 2.36 mm x 0.6 mm), has a high performance with 5.5 dB insertion loss at the central frequency and a transmission attenuation over 20 dB for fo ± 1.6 GHz. Index Terms Low temperature co-fired ceramic (LTCC), quasi-elliptic filter, resonant cavity, submillimeter wave range.