Patent AT-E401696-T1: [Translated] WIRELESS TERMINAL

A wireless terminal having a dual band antenna arrangement which comprises a planar inverted-F antenna ( 10 ) having a first ( 12 ) for signals in a first, lower frequency band, for example the GSM band, a second feed ( 14 ) for signals in a second, higher frequency band, for example the DCS band, and a ground pin ( 16 ). A first coupling stage ( 26 A) couples the transmit and receive paths of a first transceiver (GSM) to the first feed and a second coupling stage ( 26 B) couples the transmit and receive paths of a second transceiver (DCS) to the second feed. Each of the first and second coupling stages comprise a quarter wavelength transmission line ( 50 A, 50 B) having a first end coupled to the respective transmit signal path and a second end coupled by band pass filter ( 52 A, 52 B) to the respective receive signal path. A first PIN diode (D 1 , D 3 ) couples a transmit signal path to the first end of the respective quarter wavelength transmission line and to the respective feed ( 12, 14 ) and a second PIN diode (D 2 , D 4 ) second end of the respective quarter wavelength transmission line to ground. In operation when transmitting in one of the bands, the first and second PIN diodes of the relevant coupling stage are switched-on, whilst the PIN diodes in the other coupling stage are off and when in a receiving mode all the PIN diodes are off. The signal being received by one of the transceivers is reflected by the band pass filter in the coupling stage of the other transceiver.