IQ combiner technology in modulated backscatter system

Claim 1

An IQ combiner for combining constructively an I output signal and a Q output signal of a demodulator, the demodulator has an input for receiving an input signal, the input signal comprises a carrier signal of a first frequency and a modulating signal where said carrier signal is modulated by the modulating signal, the modulating signal comprises a subcarrier of a second frequency and an information signal where said subcarrier is modulated by the information signal, and the I output signal is orthogonal to the Q output signal of the demodulator with respect to the first frequency, said IQ combiner comprising: a phase shifter having an input and an output where said phase shifter introduces a phase delay of 90° with respect to the second frequency to a signal applied to its input and an adder having an output, a first input, and a second input where the output of the phase shifter is connected to the first input of the adder and when one of the output signals of the demodulator is applied to the second input of the adder while the other output signal of the demodulator is applied to the input of the phase shifter the output of the adder is a vectorial sum of its input signals.