Zweibandsendeempfänger

According to the present invention, a dual band transceiver is presented comprising a baseband block (1), frequency converting blocks (2, 3) and a plurality of antenna systems (4, 5). The first frequency converting block (3) is connected between the baseband block (1) and at least one antenna (4, 5) and converts an intermediate frequency IF1 output of the baseband block (1) or another frequency converting block (2). According to the present invention a first transmission frequency band RF1 of the dual band transceiver corresponds to the intermediate frequency IF1, IF2, and a second transmission frequency band RF2 is obtained as an output signal of the first frequency converting block (2, 3). Therefore communication device comprising a dual band transceiver according to the present invention can switch from a LOS transmission, for example, with a frequency higher than 10 GHz to a NLOS communication with a transmission frequency smaller than 10 GHz. For switching (6, 7) the frequencies RF1, RF2, a control unit (8) is provided, wherein the switch control effected by the control unit (8) is effected on the base of for example channel characteristics, user preferences, and the bit error rate of the transmission. The control unit (8) is furthermore connected to the baseband block (1) to change modulation parameters of the baseband block (1) simultaneously to the switching between the first transmission frequency band (RF1) and the second transmission frequency band (RF2).