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Item type:Publication, Access status: without files , An Accurate Free Space Method for Material Characterization in W- Band Using Material Samples with Two Different Thicknesses(2018-11-20); ; ; ; This paper presents an accurate free space method for material characterization eliminating the problem of the required precise orientation between the material and the antennas and expanding the unambiguous range for electrical thick samples. It includes theoretical considerations and measurement results of four different materials. Overall, a maximum measurement uncertainty of 0.0153 for the relative permittivity and 0.001 for the loss tangent in the W-band can be achieved. Depending on the variation of the material's thickness, the implemented setup changes lead to an reduction of the measurement uncertainty of 8 to 58 %.Publicationtype: Conference Paper99 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Resonant Substrate Integrated Waveguide Measurement System for True Relative Permittivity Extraction of PCB Materials up to 90 GHz(2018-09-06); ; ; ; This paper presents a resonant measurement method based on substrate integrated waveguide cavities for determination of the true relative permittivity of a PCB material. The sensor is manufactured on the unknown PCB material and in contrast to existing, comparable methods, the extraction process takes into account the metal roughness. The proposed method does not require any reference materials or sensors on different PCB thicknesses. This paper contains considerations regarding the design and simulation as well as measurement results of the sensor system. To validate the measurement system, the extracted relative permittivity values of the RO4350B substrate over the frequency range of 10GHz to 90GHz are presented.Publicationtype: Conference Paper83 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Porösizierte Glaskeramik-Substrate für die Radarsensorik(Springer, 2018); ; ; ; Publicationtype: Book Part109 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , In-line material characterization sensors operating at 10GHz and 77GHz(2017-06-28); ; ; This paper describes the design of two sensors for the in-line material characterization of bulk and metallized dielectrics around 10GHz and 77GHz in order to determine the relative permittivity of RF substrates. The sensors are based on a resonant grounded coplanar waveguide structure and can be applied on top of a material under test. The shift in the resonance frequency between loaded and unloaded resonator is evaluated by 3D full wave simulations to determine the relative permittivity. The basic sensor structure is improved for the inline characterization of printed circuit boards by a clearance of the resonator area and the filling of the air gaps. Measurements with different MUTs were performed with both sensors followed by the evaluation of the relative permittivity. The results are in good agreement with the expected permittivity values and show high reproducibility.Publicationtype: Conference Paper97 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A Coplanar Waveguide Resonator Based In-Line Material Characterization Sensor for Bulk and Metallized Dielectrics(2017-03-01); ; ; ; Microwave Materials such as Rogers RO3003 are subject to process-related fluctuations in terms of the relative permittivity and dielectric loss. The behavior of high frequency circuits like patch-Antenna arrays and their distribution networks is dependent on the effective wavelength. Therefore, fluctuations of the complex permittivity will influence the resonance frequency and beam direction of the antennas. This paper presents a grounded coplanar waveguide based sensor, which can measure the complex permittivity at 77GHz, as well as at other resonance frequencies, by applying it on top of the manufactured depaneling. The relative permittivity of the material under test (MUT) is a function of the resonance frequency shift and the dielectric loss of the MUT can be determined by transmission amplitude variations at the resonances. In addition, the sensor is robust against floating ground metallizations on inner printed circuit board layers, which are typically distributed over the entire surface below antennas. Furthermore, the impact from conductor surface roughness on the measured permittivity values is determined using the Gradient Model.Publicationtype: Conference Paper93 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Concentration and temperature dependent selectivity of the LTCC porosification process with phosphoric acid(2017-01-01); ; ; ; The wireless high frequency (HF) technology requires a robust, well-established and cost-effective substrate solution with a tailored permittivity. The wet-chemical porosification of low temperature co-fired ceramics provides such a substrate by locally embedding air into the surface. The present study investigates the relation of air embedment and surface alteration in detail, utilizing gravimetric methods as well as scanning electron microscopy with and without focused ion beam technology. The porosification approach could successfully be transferred from the DuPont 951, which features a high selectivity, to Heraeus CT 702 with good HF performance. By applying ring-resonator based permittivity measurements, a similar permittivity reduction by approx. 10% at a maximum frequency of 70 GHz could be confirmed. The optimum etch parameters for an LTCC allowing a further metallization are a phosphoric acid mass fraction of 50 wt%, a temperature of 100 °C at maximum and a minimum treatment time of 8 h.Publicationtype: Journal Article63 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Permittivity reduction and surface modification by porosification of LTCC(2016-05-15); ; ; ; The wet-chemical porosification of low temperature co-fired ceramics is investigated with respect to the resulting permittivity reduction and surface modification. Therefore, four commercially available tapes are characterized by means of a detuned ring resonator as well as by chromatic white light and scanning electron microscopy analyses. The results show a technically relevant permittivity reduction of about 15% to 18% measured at a frequency of 44 GHz. Thereby, the vertical distribution of the air, embedded by the porosification, is of high influence. The achievable reduction in permittivity strongly counteracts the surface quality, which is necessary for applying high quality metallization lines.Publicationtype: Journal Article66 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Pulse plated silver metallization on porosified LTCC substrates for high frequency applications(2016-05-01); ; ; ; Advanced high frequency systems such as needed in modern radar applications, require high conductive metallizations as well as substrates with areas of variable permittivity. This paper presents the combination of the selective porosification technology of low temperature co-fired ceramics (LTCC) and electro pulse plated silver microstrip lines. By means of selective plating methods, line widths of 20 μm can be manufactured featuring low resistivity values down to 2.33 μΩ cm, without detectable pore penetration. The substrate permittivity is measured facilitating a combined method of ring resonator detuning and 3D field simulations resulting in a reduction of 6.5% with a shift from approx. 7.52 to 7.03 at 66 GHz due to the porosification. As often outlined in literature, the major challenge in using silver as a conductor lies in its high tendency of agglomeration and microstructural transformation especially in oxygen containing atmosphere even at low temperatures. Therefore, the effect of different temperature loads up to 500°C on the dc film resistivity is measured using the van der Pauw technique and is compared to scanning electron microscope analyses.Publicationtype: Journal Article51 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A grounded coplanar waveguide resonator based in-line material characterization sensorMicrowave Materials such as Rogers RO3003 are subject to process-related fluctuations in terms of the relative permittivity. The behavior of high frequency circuits like patch-Antenna arrays and their distribution networks is dependent on the effective wavelength. Therefore, fluctuations of the relative permittivity will influence the resonance frequency and antenna beam direction. This paper presents a grounded coplanar wave-guide based sensor, which can measure the relative permittivity at 77 GHz, as well as at other resonance frequencies, by applying it on top of the manufactured depaneling. In addition, the sensor is robust against floating ground metallizations on inner printed circuit board layers, which are typically distributed over the entire surface below antennas.Publicationtype: Conference Paper175 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Embedded cavity based dielectric loss measurements for LTCC substrates up to 110 GHz(2016-02-19); ; ; ; In literature there exists manifold techniques for measuring the permittivity of substrates. Printed circuit board (PCB) based methods like dielectric resonators are in general limited to determine the absolute value of the complex permittivity since e.g., a half wave resonator only provides information on the electrical length, which is inversely proportional to the square root of the absolute value of the permittivity. Additionally, dielectric loss measurements are more difficult, expensive and often limited to discrete frequency points due to resonance based measurement principles. In this paper, a PCB based dielectric loss measurement system is presented, operating from a few GHz up to 110 GHz, which is based on a differential measurement of a microstrip line on dense low temperature cofired ceramics (LTCC) and a microstrip on a LTCC layer with an embedded cavity. The cavity reduces the dielectric loss of the transmission line by replacing a certain amount of substrate with air. Subsequent electromagnetic time domain field simulations allow the dielectric loss assignment over the measured transmission frequency range.Publicationtype: Conference Paper87