Olivier Tantot

Characterization of liquid crystal polymer (LCP) material and transmission lines on LCP substrates from 30 to 110 GHz

Liquid crystal polymer (LCP) is a material that has gained attention as a potential high-performance microwave substrate and packaging material. This investigation uses several methods to determine the electrical properties of LCP for millimeter-wave frequencies. Microstrip ring resonators and cavity resonators are measured in order to characterize the dielectric constant (/spl epsi//sub r/) and loss tangent (tan/spl delta/) of LCP above 30 GHz. The measured dielectric constant is shown to be steady near 3.16, and the loss tangent stays below 0.0049. In addition, various transmission lines are fabricated on different LCP substrate thicknesses and the loss characteristics are given in decibels per centimeter from 2 to 110 GHz. Peak transmission-line losses at 110 GHz vary between 0.88-2.55 dB/cm, depending on the line type and geometry. These results show, for the first time, that LCP has excellent dielectric properties for applications extending through millimeter-wave frequencies.

Continuously Tuned Ku-Band Cavity Filter Based on Dielectric Perturbers Made by Ceramic Additive Manufacturing for Space Applications

This paper presents a concept of a tunable cavity resonator composed of a resonating cavity and a dielectric perturber. This tunable resonator is designed and measured to prove the tuning mechanism obtained by varying the angle of rotation of the perturber. A rotation from 0 to 90 produces a tuning ratio of 1:1.25, i.e., a tuning range of 22.2% around 11.5 GHz while maintaining an unloaded Q factor between 1500 and 2300. After this first experimental validation, a third-order bandpass filter is then designed and measured using the same base principle. Using a single mechanical movement, all three resonators’ perturbers are synchronously rotated to create a third-order Chebyshev bandpass filter maintaining a 516±38-MHz bandwidth (for a return loss better than 10 dB) from 9.915 to 12.189 GHz. A 20.6% tuning range is then obtained at approximately 11 GHz with an estimated Q factor from 1400 to 2150. These performances have been obtained by using specifically shaped dielectric perturbers, which have been made by a ceramic additive manufacturing (AM) process (stereolithography). This technology has enabled the perturbers’ specific geometries and embedded supporting elements to be feasible. A sixth-order Chebyshev bandpass filter has also been theoretically proposed using full wave simulations.

3D printing of microwave passive components by different additive manufacturing technologies

This paper presents an overview of the possibility offered by 3D plastic printers for a quick, simple and affordable manufacturing of working filters and other passive devices such as antennas. This paper thus goes through numerous examples of passive devices made with the Fused Deposition Modeling (FDM) and material jetting (Polyjet©) technologies and will highlight how they can now be considered as a solid companion to RF designers during an optimization process up to Ku and higher bands.

A dual-mode dual-band bandpass cavity filter with widely separated passbands

A compact dual-mode dual-band filter with widely separated passbands is proposed for possible integration in a TX/RX front-end. The basic structure is a cavity working on two distinct dual-modes. The design of this cavity realizing a 4-pole dual-band filtering function is detailed. A prototype is fabricated and measured for validating the concept.

Multimaterial inkjet technology for the fabrication of multilayer components

In this paper, we report the printing of multilayered structures mixing silver nanoparticles and low temperature fired ceramics based inks. The conductivity of the silver ink is characterized up to 20GHz and above, and the typical performances of the technology and used dielectric material are given. A metallo-dielectric printed capacitance is finally presented as a first demonstrator.

Additive manufacturing of microwave antennas up to 60 GHz

This paper presents three different microwave antennas made by plastic additive manufacturing. Firstly two broadband mode converters made with the Polyjet© technology are presented with their measurement. They can be used as E-plane omnidirectional antennas. The first one is designed to work in the Ka-band (measured from 28 to 36 GHz) and the second is made to work in the V-band (measured from 45 to 61 GHz). The experimental behaviour closely matches the simulated results with a realized gain contained between 6 and 8dB over the different frequencies bands. The last device is a Gaussian corrugated horn antenna designed to work over the Ka band, between 26 and 40 GHz. A first outlook of the expected performances and the fabricated prototypes are presented in this paper along.

A dual-mode high-Q tunable filter reconfigured by cavity rotation

This paper proposes a new solution for implementing high-quality-factor tunable filters, suitable for high-power handling. The dual-mode filter is realized with a cylindrical cavity, which comprises metallic lugs and is loaded by a dielectric element. The center frequency is tuned between two states, by adjusting mechanically the position of the lugs within the cavity. The lugs allow modifying the capacitive effect between the dielectric element and the cavity for adjusting the resonant frequency.

A microwave sensor for zinc corrosion detection

This article presents a sensor based on zinc wires of different widths deposited on the surface of the ceramic resonator capable of detecting and following the evolution of the corrosion of the zinc material. Electromagnetic studies show that due to the evolution of the corrosion, the progressive degradation of the conductivity of the formed zinc grid (from 6 S/μm to 0.015 S/μm) causes a degradation of the quality factor (from Q0 = 50 to Q0 < 5), a decreased level of the coefficient transmission of the TE101 mode of the resonator (from -8 dB to <-35 dB), and a progressive frequency shift (230 MHz). Experimental measurements of this sensor in a corrosive environment show a gradual shift of the resonance frequency of the TE101 mode, a decreased level of the S21 transmission coefficient, and a degradation of the unloaded quality factor. Confirmed by electronic microscopy and X–Ray analysis, these variations are due to the evolution in the corrosion of zinc wires over time, leading to a creation of corrosion ...

High Temperature Dielectric Measurement using the TE11 Mode in Circular Waveguide Radiating Through a Small Thick Aperture

The reflection coefticient of the dominant TE11 incident mode of a flanged circular waveguide radiating through a thick aperture into layered dielectric media, raised to high temperature, has been studied. Complex permittivity measurements of a few materials at room temperature have been realized with various dimensions of aperture in order to define the validity domain of the method. The use of a hot air wind tunnel made it possible to reach a high temperature in a short time.