Abstract: A waveguide band-pass filter is disclosed comprising: an input/output gate for a signal; a first inductive discontinuity coupling device; a second inductive discontinuity coupling device and a first waveguide resonator segment coupled to said input/output gate and interposed between the first and the second coupling devices. At least one of the first and the second coupling devices includes at least a resonant coupling structure which extends in the waveguide with a reduced height relative to a height of the first resonator segment and it is shaped for inputting a zero in a transmission frequency response of the filter.

Abstract: A waveguide band-pass filter is disclosed comprising: an input/output gate for a signal; a first inductive discontinuity coupling device; a second inductive discontinuity coupling device and a first waveguide resonator segment coupled to said input/output gate and interposed between the first and the second coupling devices. At least one of the first and the second coupling devices includes at least a resonant coupling structure which extends in the waveguide with a reduced height relative to a height of the first resonator segment and it is shaped for inputting a zero in a transmission frequency response of the filter.

Abstract: A testing system includes simulation equipment for generating a radiofrequency test signal for the receivers of a base transceiver station, which is equipped with an intelligent array antenna having N sensors. The simulation equipment generates a complex signal consisting of N identical radiofrequency signals with differing phases. These signals are conveyed towards N antenna input connectors of the receivers to be tested. The N test signals are obtained by generating as many groups of N digital isofrequential carriers as are required to simulate the directions of a useful signal with an arbitrary number of echoes, and the directions of an arbitrary number of isofrequential interferent carriers. The N carriers of each group are appropriately modulated and digitally multiplied by the same number of relevant beamforming coefficients to produce, within each group, gradually increasing phase values.

Abstract: It is described an image rejection, sub-harmonic frequency converter, realized in microstrip, particularly adapted to be used in mobile communication equipment, The converter avails of two identical sub-harmonic mixers employing each one or two pairs of diodes in antiparallel, obtained on a same silica substrate, and of a structure of hybrids performing appropriate phase combination adapted to suppress the image band in the converted signal. The mixers include filtering structures preferably consisting, but no limited to the same, of stubs &lgr;/4 long, at the local oscillator frequency, having a free end, in short or open circuit, respectively. According to an alternative embodiment, said stubs are replaced by appropriate filters implemented with concentrated structures (L and C) performing the same transfer function of the stubs in microstrip.

Abstract: A broad band digital radio receiver for multicarrier signals employs a quadrature demodulator to directly shift the radiofrequency signal in a base band. A local oscillator has frequency f0 placed at the center of the radiofrequency BW band, so channel pairs, symmetric versus f0, are superimposed in the lower base half-band. Base band equivocation is then solved by numeric-type second orthogonal demodulators, which supply pairs of twice-demodulated signals that can be grouped in four equation systems in four unknown values consisting of in-phase and quadrature components of the two channels of each pair. Subsequent reconstruction networks solve the relevant systems and give the two components of each single channel for each pair. One network in the receiver measures amplitude and phase dissymmetries in the two branches of the analog demodulator and supplies four corresponding digital coefficients to the reconstruction network, which can then counterbalance at output the effects of dissymmetry.

Abstract: It is described a broadband radio transmitter for a digital signal consisting of a plurality of not necessarily equispaced, digitally modulated carriers. The transmitter selects the second replica of the spectrum of the signal coming out from a digital-to-analogue converter DAC to increase the space of the useful signal from the continuous in comparison of the direct use of the base band spectrum would involve. The object of the invention is in fact to obtain a wider transition band and consequently a less stringent local oscillator residue and image filter at radio frequency. To eliminate or reduce the effect of the sin(&pgr;fT)/(&pgr;fT) function that envelopes the signal coming out from the DAC, the invention foresees the use of an equalization of the analogue type, or the adoption of a zero insertion technique (of the digital or analogue type) or in general a digital x/sin x equalizer.