1. A device for emitting and/or receiving signals in at least two symmetrical frequency bands in relation to a first central
frequency of symmetry F_{CA }and such that each one of the at least two frequency bands comprises at least two channels, or groups of channels, symmetrical
in relation to second central frequencies of symmetry, including a central lower frequency F_{CLA}, and a central upper frequency F_{CUA}, said device comprising at least:
a first circuitry able to generate a periodic signal of frequency F_{A}, a periodic signal of frequency F_{B}=F_{A}/N1, a periodic signal of frequency F_{1 }equal to F_{CA}−F_{CLA} and a periodic signal of frequency F_{2 }equal to the difference between a central frequency of one of the at least two channels or groups of channels and the second
frequency of symmetry associated with said one of the at least two channels or groups of channels, and wherein
F_{A}=N1·(F_{CLA}+F_{1})/(N1+1) with N1 being a number greater than 1;
a second circuitry able to carry out a first nonlinear operation between the periodic signals of frequencies F_{A }and F_{1 }generating a first multitone signal of which the frequency spectrum comprises two main lines at frequencies F_{A}−F_{1 }and F_{A}+F_{1}, and able to carry out a second nonlinear operation between the periodic signals of frequencies F_{B }and F_{2 }generating a second multitone signal of which the frequency spectrum comprises two main lines at frequencies F_{B}−F_{2 }and F_{B}+F_{2}.
