A phase shifting apparatus, comprising: a grounding plate; at least two bottom substrates arranged on respective sides of the grounding plate and coupled to the grounding plate such that the grounding plate is arranged between the at least two bottom substrates; at least two top substrates arranged on respective sides of the two bottom substrates such that the grounding plate and the two bottom substrates are arranged between the at least two top substrates, wherein a first one of the top substrates and a first one of the bottom substrates form a first phase shifting unit, and wherein a second one of the top substrates and a second one of the bottom substrates form a second phase shifting unit; a rod coupled to the two top substrates, wherein the rod is configured to adjust a relative sliding movement between the at least two top substrates and the at least two bottom substrates and to simultaneously adjust a phase of an output signal of each phase shifting unit; a fixing part for fixing the two top substrates in relation to each other, wherein the rod is coupled to the two top substrates via the fixing part, wherein the fixing part comprises a first fastening piece and a second fastening piece that are configured to be fastened with each other, wherein the top substrates and the bottom substrates are attached when the first fastening piece is fastened to the second fastening piece, characterized in that the first fastening piece comprises at least one first rivet and at least one first groove, that the second fastening piece correspondingly comprises at least one second rivet and at least one second groove, such that a fixed connection between the first fastening piece and the second fastening piece is formed by a first matching between the at least one first rivet of the first fastening piece and the at least one second groove of the second fastening piece and by a second matching between the at least one second rivet of the second fastening piece and the at least one first groove of the first fastening piece, that each of the top substrates is provided with at least two through-holes for allowing the at least one first rivet of the first fastening piece and the at least one second rivet of the second fastening piece to pass through; and that each of the bottom substrates is provided with at least one slot hole for providing a movement space for the at least one first rivet of the first fastening piece and the at least one second rivet of the second fastening piece. a grounding plate; at least two bottom substrates arranged on respective sides of the grounding plate and coupled to the grounding plate such that the grounding plate is arranged between the at least two bottom substrates; at least two top substrates arranged on respective sides of the two bottom substrates such that the grounding plate and the two bottom substrates are arranged between the at least two top substrates, wherein a first one of the top substrates and a first one of the bottom substrates form a first phase shifting unit, and wherein a second one of the top substrates and a second one of the bottom substrates form a second phase shifting unit; a rod coupled to the two top substrates, wherein the rod is configured to adjust a relative sliding movement between the at least two top substrates and the at least two bottom substrates and to simultaneously adjust a phase of an output signal of each phase shifting unit; a fixing part for fixing the two top substrates in relation to each other, wherein the rod is coupled to the two top substrates via the fixing part, wherein the fixing part comprises a first fastening piece and a second fastening piece that are configured to be fastened with each other, wherein the top substrates and the bottom substrates are attached when the first fastening piece is fastened to the second fastening piece, characterized in that the first fastening piece comprises at least one first rivet and at least one first groove, that the second fastening piece correspondingly comprises at least one second rivet and at least one second groove, such that a fixed connection between the first fastening piece and the second fastening piece is formed by a first matching between the at least one first rivet of the first fastening piece and the at least one second groove of the second fastening piece and by a second matching between the at least one second rivet of the second fastening piece and the at least one first groove of the first fastening piece, that each of the top substrates is provided with at least two through-holes for allowing the at least one first rivet of the first fastening piece and the at least one second rivet of the second fastening piece to pass through; and that each of the bottom substrates is provided with at least one slot hole for providing a movement space for the at least one first rivet of the first fastening piece and the at least one second rivet of the second fastening piece.