Wave transmission lines and networks – Coupling networks – Equalizers
Reexamination Certificate
1999-08-25
2001-10-23
Pascal, Robert (Department: 2817)
Wave transmission lines and networks
Coupling networks
Equalizers
C333S018000, C375S229000
Reexamination Certificate
active
06307444
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an arrangement for the equalization of a frequency signal, the arrangement including a channel filter and an equalizer connected downstream from the channel filter, for a satellite communication system in particular.
BACKGROUND INFORMATION
A conventional method for the transmission of information via a satellite link is to convert the information into high frequency signals and to transmit them. In order to be able to transmit a large amount of information simultaneously, several selectable frequency bands of the total frequency spectrum suitable for a transmission are used for the transmission. These high frequency signals are transmitted from an earth station to a satellite and from the satellite to the receivers. The transmitted signals are converted and amplified in the satellites. Since the broadband amplifiers themselves cannot be implemented, the signals are broken down into relatively narrow frequency bands. These signals are amplified and subsequently combined to form the output signal and then transmitted.
In this connection, it is disadvantageous that a so-called skew occurs between the low, medium and high frequency signal components within a narrow band frequency band. The skew results in corrupted signals when the signals are subsequently combined and amplified. A conventional method for balancing the skew is to guide the signals via an equalizer having a circulator. The transmitted signal is injected in the circulator and sent to an output terminal via controlled reflections within the circulator. This reduces the group delay of the signal, i.e., the transmission time of the low, medium and high frequency signal components of a signal takes place in a shorter time interval. The use of a microwave equalizer in satellite communication systems is described in, for example, C. M. Kudsia, Synthesis of Optimum Reflection-Type Microwave Equalizers, RCA Review, September 1997, page 571 ff. Waveguide resonators or dielectric resonators having a downstream, short-circuited, double-tuned circuit filter are customarily used for this purpose. A disadvantage of such resonators is their relatively large size and, consequently, the use of a large number of such resonators in a satellite communication system, especially, in a satellite itself, is limited.
The manufacture of filters using superconductive planar technology is also generally known. In contrast to conventional filters and equalizers, they represent a considerable savings in space and weight.
SUMMARY OF THE INVENTION
An arrangement according to the present invention offers an advantage that, in addition to a reduction of space and weight, a further reduction of group delay is also achieved. As a result of the equalizer being made up of an at least partially superconductive reflection equalizer, preferably including a planar circulator and a superconductive reflection filter, equalization of the signals and reduction of the group delay can take place in an extremely small installation space due to the use of components based on superconductive planar technology. The low frequency and high frequency signal components of the signal of a certain frequency band to be transmitted are superimposed via the reflection filter in such a way that their delay is approximated to the delay of the medium frequency signal component, resulting in a drastic reduction of the variation of the group delay.
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Mansour et al. “C-Band Externally-Equalized Superconductive Input Channel Filters.” 1994 IEEE International Microwave Symposium-Digest. vol. 1. pp. 187-190 (May 23-27, 1994).*
Weigel et al. “Narrow-Band YBCO Superconducting Parallel-Coupled Coplanar Waveguide Band-Pass Filters At 10 GHZ.” 1993 IEEE MTT-S International Microwave Symposium-Digest. vol. 3. pp. 1285-1288 (Jun. 14, 1993).*
R. Knerr. “A Microwave Circulator That's Smaller Than A Quarter.” Bell Laboratories Record. vol. 51. No. 3, pp. 79-84 (Mar. 1973).
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Klauda Matthias
Neumann Christian
Glenn Kimberly E
Kenyon & Kenyon
Pascal Robert
Robert & Bosch GmbH
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