Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Reexamination Certificate
1998-06-01
2001-10-16
Bost, Dwayne (Department: 2681)
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
C455S226100, C455S425000
Reexamination Certificate
active
06304747
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method and a measurement system for creating a virtual antenna reference point to be used in testing of active antennas containing distributed amplifier modules.
BACKGROUND
Today radio performance typing of the present generation of base stations according to standard requirements (for instance GSM, PDC and DCS) is performed by measurement in an antenna reference point. This point is defined by the current standard and is constituted by the antenna connector terminal and should regarding transmission be located after active electronics, but regarding reception be located before the electronics.
When utilizing active antennas having distributed amplifiers this approach leads to problems. Each transmitter and receiver module, respectively, is connected to one or more antenna elements and the merging of the signals takes place in the air. For this type of antennas a new type of antenna reference point must be defined.
One method of measurement could be to individually measure each radiating element interface and state a type acceptance for each unit as such. This would lead to a very large number of measurements and produce a result which would not be representative for the signal environment resulting of the merging in the air. The position in space and relative amplitudes of spuriouses and main signal will not be measured, however this is entirely of vital importance for the resulting signal representation.
Another method is to measure radiation pattern by means of an antenna test range. This method is very difficult as it is necessary to maintain a safe control of undesired disturbance sources. That is practically impossible as certain measurements are performed at signal levels of −110 dBm and less. If the measurements are performed in an unshielded room or outdoors it will be disturbed by present active mobile telephones and when performing transmit tests, telephone systems operating in the neighborhood may be disturbed by such a test.
There will be found a number of documents relating to calibration of phased array antennas, for instance U.S. Pat. No. 5,063,529 disclosing utilization of automated processing techniques to compute calibration coefficients based on a generalized model of the array. However the documents relating to such calibrations are not dealing with systems having active antennas with distributed amplifiers.
Therefore there is a large need for a new method for performing a reliable test method for an active antenna system containing distributed amplifiers for instance for use in base stations for radio telephone systems like GSM, PDC or DCS.
SUMMARY OF THE INVENTION
A method according to the present invention proving to be practically usable is a merging of signals feeding the antenna elements in transmit by means of a combiner network or feeding distributed low noise amplifiers by means of a combiner network substituting the antenna elements, to thereby create an antenna reference point. The result of this signal merging will be easily accessed for measurement purposes.
Consequently, the present invention discloses a method and a measurement system creating a virtual antenna reference point which for testing and typing active antennas having distributed electronics for a certification according to standards for GSM, DCS and PDC. The present method is set forth in the independent claim
1
and a measurement system for applying the method is set forth in the independent claims
11
and
12
, while different embodiments of the method according to the present invention are set forth in the dependent claims
2
-
10
.
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patent: 5574981 (1996-11-01), Ahonen
patent: 5604462 (1997-02-01), Gans et al.
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patent: 5790944 (1998-08-01), Karki et al.
patent: 0 461 314 (1991-12-01), None
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Audone, B. ‘Interaction between test site and amplifier nonlinearities in susceptibility tests’ IEEE, pp. 1-4, Aug. 1994.*
Panton, W.R. et al ‘The noise performance of an active, linear antenna array for reception’ IEEE Microwave Symposium, pp. 1-10, May 1994.
Derneryd Anders
Loostrom Lars
Bost Dwayne
Burns Doane Swecker & Mathis L.L.P.
Craver Charles
Telefonaktiebolaget LM Ericsson (publ)
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