| 摘要 |
AN ANTENNA SYSTEM (133), IS COMPRISED OF A PLURALITY OF INDEPENDENTLY CONSTRUCTED AND OPERATED ANTENNA UNITS, UPON WHICH ARE MOUNTED A PLURALITY OF TRANSMIT AND RECEIVE ANTENNA PAIRS. THIS PROVIDES A MEANS FOR THE ANTENNA SYSTEM (133) TO BE ARRANGED TO PROVIDE SUBSTANTIALLY HEMISPHERICAL RADIO COVERAGE. BY ADJUSTING THE PHASE OF EACH VERSION OF A RADIO SIGNAL TO BE TRANSMITTED OR RECEIVED, THE SIGNAL MAY BE FORMED INTO A BEAM, ACCORDING TO THE KNOWN TECHNIQUE OF DIRECTIONAL BEAM FORMING, PROVIDING THE ANTENNA SYSTEM WITH DIRECTIONAL GAIN. FURTHERMORE, USING A PLURALITY OF TRANSMIT AND RECEIVE ANTENNA PAIRS REDUCES THE ENERGY TRANSMITTED BY EACH TRANSMIT ANTENNA ALONE TO A LEVEL WHICH PERMITS A BRANCH LINE COUPLER TO BE SUFFICIENT TO ORTHOGONALLY POLARISE THE TRANSMITTED AND RECEIVED RADIO SIGNALS, NEGATING THE REQUIREMENT FOR A DUPLEXING FILTER FOR DUPLEX OPERATION.
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