T 1876/09 () of 1.7.2013

European Case Law Identifier: ECLI:EP:BA:2013:T187609.20130701
Date of decision: 01 July 2013
Case number: T 1876/09
Application number: 01914265.2
IPC class: H01Q 3/26
G01S 7/40
Language of proceedings: EN
Distribution: D
Download and more information:
Decision text in EN (PDF, 137.397K)
Documentation of the appeal procedure can be found in the Register
Bibliographic information is available in: EN
Versions: Unpublished
Title of application: Self-calibration of feeders for array antennas
Applicant name: Telefonaktiebolaget LM Ericsson (publ)
Opponent name: -
Board: 3.4.01
Headnote: -
Relevant legal provisions:
European Patent Convention 1973 Art 84
Keywords: Clarity (no, all requests)
Catchwords:

-

Cited decisions:
-
Citing decisions:
-

Summary of Facts and Submissions

I. European patent application 01 914 265.2 (publication No. WO 01/71850) was refused by a decision of the examining division dispatched on 15 April 2009 for the reason of lack of inventive step (Articles 52(1) and 56 EPC 1973) of the subject-matter of the claims of the requests then on file.

II. The applicant lodged an appeal against the decision on 9 June 2009. The prescribed appeal fee was paid on the same day. A statement of grounds of appeal was filed on 12 August 2009.

The appellant requested that the decision under appeal be set aside and that the application be remitted to the examining division for further prosecution on the basis of a set of claims 1 to 7 filed with telefax on 27 May 2008, by way of a main request, or on the basis of a set of claims 1 to 5 filed with telefax on 15 January 2009, by way of an auxiliary request.

III. On 7 February 2013 the appellant was summoned to oral proceedings to take place on 13 June 2013.

In an annexed communication pursuant to Article 15(1) RPBA the Board identified inter alia problems having regard to the clarity of the claims on file.

IV. The appellant did not comment on the Board's observations nor did it file any further amendments. Instead, by letter dated 19 February 2013 the appellant informed the Board that it had decided not to attend the oral proceedings and announced that no written submission would be filed.

V. Oral proceedings were cancelled by notification of 5 March 2013 and the appellant was informed that a decision was to follow in writing.

VI. Independent claims 1 and 4 and dependent claim 3 of the appellant's main request read as follows:

"1. A method for self-calibration of feed cables of an array antenna for compensating a difference in receive and transmit frequency, the electrical length of each feed cable is known, comprising the steps of

calculating a first feed cable phase weight set WRX‹k›during reception by an adaptive algorithm for a received signal at a receive frequency fRX, wherein k is the index of a k:th antenna element in the array antenna and whereby a full electrical feed cable length is accounted for in the calculation;

characterized by that the same feed cables are used for receive and transmit paths, said method further comprising the steps of

calculating from the first feed cable weight set WRX‹k›a corresponding second cable phase weight set WTX‹k›for a chosen transmit frequency fTX, said transmit frequency differs from said receive frequency, applying a proportional relation fTX/fRX, and

applying the corresponding second cable phase weight set WTX‹k›as a phase correction of the array antenna feed cables at transmit frequency fTX, to thereby facilitate a continuous beam steering with coinciding receive and transmit directions.

3. The method according to claim 1, characterized by the further step of using an adaptive beam forming algorithm such as a Sample Matrix Inversion (SMI) to compute a phase weight set that will produce a main transmit beam in the direction of one of the signals in the receive direction.

4. A system for self-calibration of feed cables of an array antenna for compensating a difference in receiving and transmitting frequency, the electrical length of each feed cable is known, comprising

means for calculating a first feed cable weight set WRX‹k›during reception by an adaptive algorithm for a received signal at a receive frequency fRX, where k is the index of a k:th antenna element in the array antenna and whereby a full electrical feed cable length is accounted for;

characterized by that the same feed cables are used for receiving and transmitting frequency, said system further comprises

means for calculating from the first feed cable weight set WRX‹k›a corresponding second cable phase weight set WTX‹k›for a chosen transmit frequency fTX, said transmit frequency differs from said receive frequency, applying a proportional relation fTX/fRX, and

means for applying the corresponding second cable weight set WTX‹k›as a phase correction of the array antenna feed cables at transmit frequency fTX, to thereby facilitate a continuous beam steering with coinciding receive and transmit directions."

Further claims 2 and 5 to 7 are dependent claims.

Independent claims 1 and 3 of the appellant's auxiliary request differ from respective claims 1 and 4 of the main request by the feature:

"according to a relation defined by

WTX‹k›= |WRX‹k›• exp ( j • (fTX/fRX) • Arg (WRX‹k›k = 1,2,.. N

wherein Arg denotes the angular phase of the argument of WRX‹k›and N is the number of elements in the array antenna,"

or

"utilizing a relation defined as

WTX‹k›= |WRX‹k›• exp ( j • (fTX/fRX) • Arg (WRX‹k›k = 1,2,.. N

wherein Arg denotes the angular phase of the argument of WRX‹k›and N is the number of elements in the array antenna,"

added respectively after the expression "applying a proportional relation fTX/fRX".

Dependent claim 2 corresponds to claim 3 of the main request and claims 4 and 5 are dependent on claim 3.

Reasons for the Decision

1. The appeal complies with the requirements of Articles 106 to 108 and Rule 99 EPC and is, therefore, admissible.

2. Clarity (Article 84 EPC 1973)

2.1 The present invention is concerned with the self calibration of feed cables of an array antenna.

In this context, the phrase "and whereby a full electrical feed cable length is accounted for in the calculation" in claim 1 of both requests on file could be misinterpreted as meaning that the respective calculation of the whole of the first feed cable phase weight set would be based on the length of only one of the feed cables.

2.2 Moreover, the indication in claims 1 and 4 of the main request "applying a proportional relation fTX/fRX" leaves doubts as to how exactly the said relation would determine the values of the second cable phase weight set. In this context, it is not apparent that any mathematical implementation of the relation fTX/fRX other than that defined by the additional feature, respectively, given in claims 2 and 5 of the main request and added into claims 1 and 3 of the auxiliary request would lead to meaningful weight values.

2.3 The expression "characterized by the further step of …" [emphasis added] given in claim 3 of the main request and claim 2 of the auxiliary request could be understood as referring to the calculation of a still further phase weight set, in addition to those referred to in respective claim 1. A similar concern arises for claims 6 and 7 of the main request and claims 4 and 5 of the auxiliary request.

2.4 For these reasons, the Board has come to the conclusion that the appellant's requests on file do not comply with the requirement of Article 84 EPC 1973.

The appellant's requests are therefore not allowable.

3. Although having been informed about the above deficiencies, the appellant neither offered any explanation nor proposed further amendments to the claims.

Given the fact that already a single deficiency renders a request unallowable, there is no need, for the purpose of the present decision, to consider other matters concerning the claims of the appellant's requests on file.

ORDER

For these reasons it is decided that:

The appeal is dismissed.

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