Papers by CHRISTOPH ERNST
A novel technique to derive the lossy equivalent circuit of waveguide external couplings of narro... more A novel technique to derive the lossy equivalent circuit of waveguide external couplings of narrowband cavity filters with arbitrary cavity cross section and arbitrary coupling geometry is presented in this contribution. The technique makes use of a reduced CAD model to obtain the element values of the equivalent lossy circuit. Therefore the contribution of the external coupling structures to the total dissipated power and total stored energy of the filter can be derived and a clear separation between resonators and couplings is established. A first degree filter has been designed, simulated, and manufactured. Its lossy equivalent circuit has been extracted and comparisons with simulation and measurement show excellent agreement.
2019 9th International Conference on Recent Advances in Space Technologies (RAST), 2019
Today, the increasing demand in higher data rates necessitates new methods as well as higher flex... more Today, the increasing demand in higher data rates necessitates new methods as well as higher flexibility for satellite telecommunication payloads in order to address a variety of applications and customers. This paper presents one of these processing strategies that is applicable to today's processing satellite payloads aiming to meet those demands. For this purpose, a two-tier filter bank is designed as part of a digital onboard processor, which first divides the spectrum at the output of the ADC into a number of sub-bands extracting all the stacked channels in the digital domain. Following the analysis section of the first tier of operations, the extracted channels go under a secondary channelisation process to obtain much finer granularity of 31.25 kHz or 50 kHz depending on the communication standard used for data transmission. The implementation of the channeliser was delivered on a bit-true simulation model and the input and the output of the channelisers were compared and evaluated both in the time and frequency domains.
2010 IEEE MTT-S International Microwave Symposium, 2010
This paper outlines the synthesis procedure for obtaining the folded coupling matrix of lossy fil... more This paper outlines the synthesis procedure for obtaining the folded coupling matrix of lossy filters of 4th order with uniform Q distribution. The method is applied to Butterworth, Chebyshev and Chebyshev with a single pair of symmetrical transmission zeros responses. Closed-form expressions to relate a prescribed insertion loss and filter bandwidth with the required resonator quality factor for an infinite Q flatness filter responses have been obtained. Experimental results on a Chebyschev microstrip filter coincide with the theoretical predictions.
IEEE Transactions on Microwave Theory and Techniques, 2013
In this paper, a novel dielectric-resonator filter configuration is presented. The new filter off... more In this paper, a novel dielectric-resonator filter configuration is presented. The new filter offers superior Q and wider spurious-mode free range at Ku-Band. Moreover, it offers 70% mass savings over the dual mode designs and over 50% footprint reduction compared with the dual-mode implementations. These characteristics make this technology well suited for the output multiplexer used in Ku-Band satellite applications. A five pole filter has been implemented to prove the superior performance of this new technology. Test data over temperature and high power test results are also presented, including a 3-Channel output multiplexer.
This paper is focused on the theoretical investigation of the relationship between the time avera... more This paper is focused on the theoretical investigation of the relationship between the time average stored energy (t.a.s.e) in conventional lumped-element Chebychev low-pass prototype filters, and the sensitivity of the return loss with respect to properly tuned resonators. It is well known that the resonant frequencies are the most sensitive parameters in a filter to achieve the required return loss and often some form of manual adjustment is needed. Different degree transfer functions, and also different topologies, are investigated throughout the paper. It is shown that both, the t.a.s.e and the sensitivity behaviors are strongly related. This work provides some new insight in fundamental properties of passive filters and can be useful for the design of filters with reduced sensitivity for high power applications and tuningless filters, for example.
On the Relation Between Stored Energy and Fabrication Tolerances in Microwave Filters
IEEE Transactions on Microwave Theory and Techniques, 2012
In this paper, a new approach for the sensitivity analysis of microwave filter networks is presen... more In this paper, a new approach for the sensitivity analysis of microwave filter networks is presented. It is shown that the standard method of sensitivity calculation based on a tuned filter is only valid for infinitesimal geometry changes and not meaningful for practical tolerance values. However, when the sensitivity calculation is expanded to also include sensitivities of detuned filters, it is shown that accurate tolerance predictions can be made even for large geometry variations. It is found that sensitivities can be related to the stored energy distribution in the filter. Transversal and ladder network-type topologies are examined, and it is demonstrated for the first time that, for in-line topologies, sensitivity can be predicted directly from the group delay of the filter in Chebyshev filters. In order to demonstrate the usefulness of the results obtained, the maximum degradation of the in-band performance has been directly obtained from the group delay for different inline filters.
This paper compares several synthesis alternatives for a 4GHz filter with 36 MHz bandwidth. The a... more This paper compares several synthesis alternatives for a 4GHz filter with 36 MHz bandwidth. The alternatives considered are: classical synthesis, various forms of pre-distortion and lossy filter synthesis. Electrical performance of the various alternatives is discussed in detail and a brief description of the topologies is also given. The synthesis of the several alternatives presented in this paper has been performed with a novel software that generates the desired transfer response, obtains the filter transverse coupling matrix and transforms it into other topologies of technological interest. The paper includes a brief description of the software features.
31st AIAA International Communications Satellite Systems Conference, 2013
The 2 nd -generation satellite digital video broadcasting (DVB-S2) system is at present under rev... more The 2 nd -generation satellite digital video broadcasting (DVB-S2) system is at present under review with the aim of improving its spectral efficiency. In this paper, we have addressed the problem to optimize the user bandwidth taking into account a realistic satellite broadcasting channel. Two different receiver architectures have been evaluated in order to maximize the system spectral efficiency. Finally, some considerations on the OMUX dissipated power have been reported. Nomenclature 1 Communication System Engineer, TEC-ETC, stefano.cioni@esa.int . 2 Microwave Engineer, TIA-TTP, christoph.ernst@esa.int . 3 Head of Communications and TT&C Section, TEC-ETC, alberto.ginesi@esa.int . 4 Associate Professor, SPADiCLab, giulio@unipr.it .
Bandpass Filter With In-Orbit Reconfigurable Bandwidth
31st AIAA International Communications Satellite Systems Conference, 2013
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Papers by CHRISTOPH ERNST