Method of calibrating a group antenna

A method of calibrating a group antenna, said group antenna comprising antenna elements (A1, A2, . . . , Am), transmitting branches (TX1 , TX2, . . . , TXm), receiving branches (RX1, RX2, . . . , RXm), means (BFT) for connecting said transmitting branches to said antenna elements for transmission, means (BFR) for connecting said receiving branches to said antenna elements for reception, said transmitting branches (TX1, TX2, . . . , TXm) including amplitude adjusting elements (ATX1, ATX2, . . . , ATXm) and phase adjusting elements (PTX1, PTX2, . . . , PTXm) so that amplitude and phase in said transmitting branches are adjustable, said method comprising the steps of:

• a) inputting a calibrating signal into one of the transmitting branches (TX1, TX2, . . . , TXm) acting as a reference branch so that said calibrating signal is radiated by an associated one of said antenna elements connected to said reference branch and thus superimposed on others of said antenna elements not connected to said reference branch;
• b) measuring superimposed signal components from the reference branch in said receiving branches (RX1, RX2, . . . , RXm);
• c) selecting each of said transmitting branches as said reference branch one after the other and repeating said inputting and said measuring of steps a) and b) for each of said transmitting branches;
• d) deriving relative amplitude and phase variations of transmission functions (s1, s2, . . . , sm) for said transmitting branches (TX1, TX2, . . . , TXm) with respect to a transmission function for a representative transmission branch, said relative amplitude and said phase variations being derived from received signals including said superimposed signal components detected in said receiving branches (RX1, RX2, . . . , RXm) for all of said calibrating signals;
• e) forming respective quotients from said transmission functions for said transmitting branches and said transmission function for said representative transmission branch;
• and
• f) adjusting said amplitude adjusting elements (ATX1, ATX2, . . . , ATXm) and said phase adjusting elements (PTX1, PTX2, . . . , PTXm) in said transmitting branches (TX1, TX2, . . . , TXm) according to said respective quotients so that said amplitude and phase variations derived in step d) are minimized.

A method of calibrating a group antenna, said group antenna comprising antenna elements (A1, A2, . . . , Am), transmitting branches (TX1, TX2, . . . , TXm), receiving branches (RX1, RX2, . . . , RXm), means (BFT) for connecting said transmitting branches to said antenna elements for transmission, means (BFR) for connecting said receiving branches to said antenna elements for reception, said receiving branches (RX1, RX2, . . . , RXm) including amplitude adjusting elements and phase adjusting elements so that amplitude and phase in said receiving branches are adjustable, said method comprising the steps of:

• a) inputting a calibrating signal into one of the transmitting branches (TX1 , TX2, . . . , TXm) acting as a reference branch so that said calibrating signal is radiated by an associated one of said antenna elements connected to said reference branch and thus superimposed on others of said antenna elements not connected to said reference branch;
• b) measuring superimposed signal components from the reference branch in said receiving branches (RX1, RX2, . . . , RXm);
• c) selecting each of said transmitting branches as said reference branch one after the other and repeating said inputting and said measuring of steps a) and b) for each of said transmitting branches;
• d) deriving relative amplitude and phase variations of reception functions for said receiving branches with respect to a reception function for a representative reception branch, said relative amplitude and said phase variations being derived from transmitted signals including said superimposed signal components detected in said receiving branches (RX1, RX2, . . . , RXm) for all of said calibrating signals;
• and
• e) adjusting said amplitude adjusting elements and said phase adjusting elements in said receiving branches so that said amplitude and phase variations derived in step d) are minimized.