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Item type:Publication, Access status: without files , Low-Cost Transmitarray Antenna Designs in V-Band based on Unit-Cells with 1 Bit Phase Resolution(2019-10-18); ; ; ; This paper presents the design and characterization of linearly polarized low-cost transmitarray antennas with ± 70° azimuth beamforming range in V-band in order to add beam steering functionality to existing radar front ends. The transmitarray antennas are composed of 13 × 13 planar unit-cells. The unit-cells consist of two layers of RO4350B laminate and provide a one bit phase resolution. The desired unit-cell behavior has been validated by simulations and measurements. Eight transmitarrays with different phase distributions have been designed and fabricated to realize different beam steering angles in azimuth. The experimental characterization of the radiation patterns shows the desired performance in the frequency range from 59 GHz to 63 GHz. Additionally, steering angle combinations in azimuth and elevation up to 40° have been realized and successfully demonstrate by measuring the 2D radiation pattern.Publicationtype: Journal Article95 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Dual-Polarized Antenna Arrays with CMOS Power Amplifiers for SiP Integration at W-Band: A Low-Cost Solution for Communication Systems with 100 Gbit/s Wireless Data Transmission(2017-08-28); ; ; This paper presents requirements and front-end solutions for low-cost communication systems with data rates of 100 Gbit/s. Link budget analyses in different mass-market applications are conducted for that purpose. It proposes an implementation of the front-end as an active antenna array with support for beam steering and polarization multiplexing over the full W-band. The critical system components are investigated and presented. This applies to a transformer coupled power amplifier (PA) in 40 nm bulk CMOS. It shows saturated output power of more than 10 dBm and power-added-efficiency of more than 10 % over the full W-band. Furthermore, the performance of microstrip-to-waveguide transitions is shown exemplarily as an important part of the active antenna as it interfaces active circuitry and antenna in a polymer-and-metal process. The transition test design shows less than 0.9 dB insertion loss and more than 12 dB return loss for the differential transition over the full W-band.Publicationtype: Journal Article119 - 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 , Second harmonic suppression in S-band traveling wave tube tapers(2015-01-29); ; ; ; Traveling wave tubes (TWTs) operating at S-band are to be improved by suppressing the second harmonic frequency. Among the different possibilities, two techniques, namely harmonic injection and a filter helix for frequency selective signal suppression, are studied in more detail and applied to S-band tubes in both simulation and measurement. In addition, their suitability to improve tube performance by reducing the second harmonic is discussed. Moreover, filter helix implementation in TWTs with an arbitrary pitch profile along the interaction area is considered. In this context, the dependence of the pitch discontinuity reflection coefficient on several filter helix parameters is investigated. The influence of those parameters on the filter performance is shown by filter helix optimization. Measurement results of the optimized filter helix TWT are presented.Publicationtype: Journal Article58 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Large-signal investigation of cold and hot matched coupled-cavity traveling-wave tubes(2015-01-29); ; The implications of different matching conditions for coupled-cavity traveling-wave tubes are considered. Using a small-signal approach the characteristic impedance for the coupled (hot) beam-wave system is derived. It is taken as reference impedance to model ideal transformers and severs. This matching condition is compared to the standard cold match and both cases are analyzed using a large-signal interaction tool. The implications on input reflection and output gain are discussed.Publicationtype: Journal Article91 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A flexible surface description for arbitrarily shaped dielectric lens antennas(2015-01-29); ; A method to efficiently describe arbitrarily shaped dielectric lens antennas based on spherical harmonics is proposed. It makes use of a Fourier-Laplace series and requires a low number of expansion coefficients, only. Symmetries can be included to impose special geometries or to further reduce the number of coefficients. The efficiency of the approach enables a fast optimization of the surface. This is particularly useful for electrically small lenses. Three exemplary lens designs based on different specifications are obtained through optimization. The manufacturing is discussed and the radiation characteristics are explored and validated through measurements.Publicationtype: Journal Article46 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Broadband patch antenna with polarization multiplexing for K-Band array applications(2011); A multilayer K-band patch antenna element featuring polarization multiplexing is presented. It relies on a previously published design providing high polarization purity. The layer stack and, in essence, the geometry are preserved. Left- and right-handed circular polarization (LHCP/RHCP) are realized without hybrid coupler, the two feeds still sharing the same layer. The arrangement is thus very compact. For interpretation, the simulation results are cast into an equivalent circuit model. Measurements performed on a multilayer antenna with vertical transitions confirm the concept.Publicationtype: Conference Paper78 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Environmental evaluation of LTCC flip-chip and surface mount technology for satellite applications(VDE Verlag, 2008-10-01); ; ; ; An environmental qualification of a hybrid technology for satellite applications is presented. It is based on low temperature co-fired ceramic modules attached in a surface mount technology to a mother board on an aluminum base plate. For the module assembly flip-chip mounting using ultrasonic and thermocompression bonding is considered. As a validation the circuits are exposed to numerous mechanical and thermal testing procedures. In three qualification steps the different manufacturing methods are evaluated and discussed.Publicationtype: Journal Article58