MicrosoftInternetExplorer402DocumentNotSpecified7.8 磅Normal0 An octave wide beamwidth central quad-ridged horn feed based on balanced feed over 4 GHz~8 GHz is designed in this paper. The central quad-ridge of the feed located at the center of the horn is cross-shaped. The external conductors of the four coaxial probes are connected to the horn wall, and internal conductors insert into central quad-ridge rotating symmetrically. Balanced feeding is achieved by feeding two coaxial probes in opposite directions with differential signals of constant amplitude and inverse-phase, which suppresses the excitation of higher order modes. The three axial corrugated slots are applied at the edge of horn aperture to obtain a stable wide beamwidth radiation pattern. The first three modes with relatively low cut-off frequencies, TE₁₁, TE_21L, TE_21U. TE₁₁is the dominant mode of the feed. Mode analysis explains the reason why the feed has broadband. The designed feed has VSWR <1.9, -3dB beamwidth>51.5° within the frequency band, E plane, and H plane cross polarization <-30dB, and the variation range of the phase center is less than 0.32l (l is the wavelength at 4GHz).