The invention relates to a wideband line source for a planar CTS (continue transverse stub) antenna. The wideband line source includes a feed network, a first rectangular waveguide and n H-faced, single-ridge and rectangular waveguide T-junctions, wherein n is an integer greater than or equal to 2; the width of each H-faced, single-ridge and rectangular waveguide T-junction ranges from 1.5 Lambda to 2.3 Lambda, wherein Lambda is equal to c / f, wherein c is velocity of light, and f is a center frequency required for the design of the wideband line source; the feed network is a power divider; the n output ends of the power divider are connected with the front ends of the n H-faced, single-ridge and rectangular waveguide T-junctions in a one-to-one corresponding manner; the rear ends of the n H-faced, single-ridge and rectangular waveguide T-junctions are connected with the front end of the first rectangular waveguide; the width of the H-faced, single-ridge and rectangular waveguide T-junction array is smaller than the width of the first rectangular waveguide by 0.5 Lambda to Lambda; and the longitudinal center line of the H-faced, single-ridge and rectangular waveguide T-junction array is overlapped with the longitudinal center line of the first rectangular waveguide. The wideband line source has the advantages of small structural size, miniaturization, wide bandwidth, simple assembly and low cost.