Abstract: In a diode mixer circuit MIX, a driving circuit DRIV produces a first, second, third and fourth drive signal DS1, DS2, DS3, DS4. Each drive signal is a combination of a first and a second input signal LO, RF with the following signs: DS1: +LO+RF DS2: +LO−RF DS3: −LO+RF DS4: −LO−RF A first, second, third and fourth diode D1, D2, D3, D4 transfer the first, second, third and fourth drive signal DS1, DS2, DS3, DS4 respectively, to an output O1. The first and fourth diodes D1, D4 have the same polarity relative to the output. The second and third diodes D2, D3 also have the same polarity relative to the output, but opposite to that of the first and fourth diodes D1, D4. A mixer circuit of this type is suitable for a relatively large variety of applications, notably because it may be realized in the form of an integrated circuit.

Abstract: A radio transmission system is disclosed for operating in a multipath transmission environment having improved reception, and in the case of bi-directional systems, also improved transmission. This is achieved by using at least two reception beams, corresponding to one fixed reception beam and one scanning reception beam, and by continuously evaluating the quality of these beams as to their signal-to-noise-and-interference ratios or bit-error-rates (BERs). The best beam is dynamically chosen to be the fixed beam. Alternatively, the fixed beam is updated with the best beam acquired by the scanning beam as compared to the current fixed beam. In a bi-directional system, the receiving radio apparatus applies the direction of the best reception beam for transmission to the opposite radio apparatus.

Abstract: A radio transmission system comprises a phased-array radio apparatus for optimizing reception in a multipath transmission environment. In the phased-array radio apparatus, phase shifting is performed after down-conversion of received RF signals. Phase control and beam-forming are simple. By applying a zero-IF or low-IF receiver structure, the complete structure can easily be fully integrated.