Wireless terminal with dual band antenna arrangement and RF module for use with dual band antenna arrangement
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.
1. A wireless terminal having a dual band antenna arrangement comprising an antenna ( 10 ) having a first feed ( 12 ) for signals in a first, lower frequency band, a second feed ( 14 ) for signals in a second, higher frequency band and a ground pin ( 16 ), first coupling means ( 26 A) for coupling transmit and receive paths of a first transceiver to the first feed, second coupling means ( 26 B) for coupling transmit and receive paths of a second transceiver to the second feed, each of the first and second coupling means comprising 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 bandpass filtering means ( 52 A, 52 B) to the respective receive signal path, a first switching device (D 1 , D 3 ) coupling a transmit signal path to the first end of the respective quarter wavelength transmission line, a second switching device (D 2 , D 4 ) coupling the second end of the respective quarter wavelength transmission line to ground, and means ( 36 ) for switching-on the first and second switching devices of one of the first and second coupling means when in a transmit mode and for switching-off the first and second switching devices when in a receive mode, the first and second switching devices of the other of the first and second coupling means being non-conductive.
2. A wireless terminal as claimed in claim 1 , characterised in that the antenna is a planar inverted-F antenna.
3. A wireless terminal as claimed in claim 1 or 2 , characterised in that the ground pin ( 16 ) is disposed between, and insulated from, the first ( 12 ) and second ( 14 ) feeds.
4. A wireless terminal as claimed in claim 1 , 2 or 3 , characterised by means ( 56 , 58 , 60 ) for reducing the voltage at a signal input of the band pass filtering means of the second coupling means.
5. A wireless terminal as claimed in any one of claims 1 to 4 , characterised in that the first and second switching devices comprise PIN diodes.
6. An RF module for use with a dual band antenna arrangement, the RF module comprising a first antenna feed ( 12 ) for signals in a first, lower frequency band, a second antenna feed ( 14 ) for signals in a second, higher frequency band and a ground pin ( 16 ), first coupling means ( 26 A) for coupling transmit and receive paths of a first transceiver to the first feed, second coupling means ( 26 B) for coupling transmit and receive paths of a second transceiver to the second feed, each of the first and second coupling means comprising 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 filtering means ( 52 A, 52 B) to the respective receive signal path, a first switching device (D 1 , D 3 ) coupling a transmit signal path to the first end of the respective quarter wavelength transmission line, a second switching device (D 2 , D 4 ) coupling the second end of the respective quarter wavelength transmission line to ground, and means ( 36 ) for switching-on the first and second switching devices of one of the first and second coupling means when in a transmit mode and for switching-off the first and second switching devices when in a receive mode, the first and second switching devices of the other of the first and second coupling means being non-conductive.
7. A RF module as claimed in claim 6 , characterised in that the ground pin ( 16 ) is disposed between, and insulated from, the first ( 12 ) and second ( 14 ) feeds.
8. A RF module as claimed in claim 6 or 7 , characterised by means ( 56 , 58 , 60 ) for reducing the voltage at a signal input of the band pass filtering means of the second coupling means.
9. The combination of a RF module as claimed in claim 6 , 7 or 8 , and an antenna ( 10 ) having means for connection to the first and second feeds ( 12 , 14 ) and the ground pin ( 16 ).
10. The combination as claimed in claim 9 , characterised in that the antenna is a planar inverted-F antenna.