Patent Publication Number: US-10784579-B2

Title: Ultra-wideband CTS flat-plate array antenna

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the priority benefits of Chinese application serial No. 201810742462.9, filed on Jul. 9, 2018. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of specification. 
     BACKGROUND 
     Technical Field 
     The invention relates to an array antenna, in particular to an ultra-wideband CTS flat-plate array antenna. 
     Description of Related Art 
     In recent years, high-sensitivity, wideband and low-profile high-performance flat-plate antennas with the characteristics of multi-band frequency and low cost have been widely used in the fields of wireless communications, ultra-wideband communications, satellite communications and the like. In 1990, the American Hughes Corporation invented a continuous transverse stub (CTS) flat-plate array antenna which adopts the TEM mode for feeding and is formed by parallel-plate waveguides provided with tangent slots. Longitudinal current components generated by the parallel-plate waveguides excited by any plane waves will be cut off by horizontal slots, longitudinal displacement currents are generated at the junction of the slots and the parallel-plate waveguides, and at this moment, energy transmitted in the parallel-plate waveguides is coupled through continuous transverse stubs, and electromagnetic waves are radiated to the outside. Compared with other flat-plate array antennas, this CTS flat-plate array antenna has the characteristics of low standing waves, high efficiency, low profile, low cost, insensitivity to fabrication precision and the like. 
     Existing CTS flat-plate array antennas typically comprise a radiating unit, a planar waveguide power dividing network and a mode switcher used for quasi-TEM mode signals, wherein the radiating unit is formed by E-plane step horns and is used for radiating a plurality of paths of signals into a free space, the planar waveguide power dividing network is formed by a plurality of stages of bisected E-plane planar waveguide power dividers and is used for dividing one path of input signals into multiple paths of signals, and the mode switcher for quasi-TEM mode signals is used for switching a single path of TE10 mode waves fed via a standard waveguide port into quasi-TEM mode waves. 
     Chinese Invention Patent Application No. 201710030209.6 discloses a CTS flat-plate array antenna which comprises a polarization layer, a radiating layer, a mode switching layer and a feed network layer, wherein the mode switching layer comprises a substrate and a mode switching cavity array disposed on the substrate. Each mode switching cavity is a one-four constant-amplitude in-phase power divider formed by a traditional rectangular waveguide. The feed network layer is used for switching a single path of TE10 mode signals fed via a standard waveguide port into multiple paths of same-power in-phase TE10 mode signals, and each path of TE10 mode signals can generate constant-amplitude in-phase plane waves after passing through the corresponding mode switching cavity. Due to the facts that the traditional rectangular waveguides have a narrow relative bandwidth and the one-four constant-amplitude in-phase power dividers forming the traditional rectangular waveguides also have a narrow relative bandwidth and are difficult to match, the relative bandwidth of the mode switching cavities is generally about 20%, which limits the relative bandwidth of the whole CTS flat-plate array antenna. The relative bandwidth of the CTS flat-plate array antenna is only 19.1% when the return loss is lower than 16 dB. 
     SUMMARY 
     The technical issue to be settled by the invention is to provide an ultra-wideband CTS flat-plate array antenna having a wide relative bandwidth. 
     The technical solution is adopted by the invention to settle the above technical issue is as follows: an ultra-wideband CTS flat-plate array antenna comprises a radiating layer, a mode switching layer and a feed network layer which are sequentially arrayed from top to bottom. The mode switching layer comprises a first metal plate and a mode switching cavity formed in the first metal plate, and the mode switching cavity comprises two mode switching units which are identical in structure and are arranged left and right in a spaced manner. Each mode switching unit comprises eight H-plane Y-type single-ridge waveguide power dividers which are arrayed in 4 rows and 2 columns, wherein the H-plane Y-type single-ridge waveguide power divider in the m th  row and 1 st  column is bilaterally symmetrical with the H-plane Y-type single-ridge waveguide power divider in the m th  row and 2 nd  column, and m=1, 2, 3 and 4. The two H-plane Y-type single-ridge waveguide power dividers in each row are connected through an E-plane T-type single-ridge waveguide power divider, and a center distance between every two adjacent H-plane Y-type single-ridge waveguide power dividers in each column is not over one wavelength. The H-plane Y-type single-ridge waveguide power divider in the m th  row and 1 st  column comprises a first rectangular cavity, an isosceles-trapezoid cavity, a second rectangular cavity, a third rectangular cavity, a fourth rectangular cavity and a fifth rectangular cavity which are sequentially formed in an upper end face of the first metal plate from right to left, the first rectangular cavity, the isosceles-trapezoid cavity, the second rectangular cavity, the third rectangular cavity, the fourth rectangular cavity and the fifth rectangular cavity are sequentially communicated front and back, are identical in height and are lower than the first metal plate, and center lines of the first rectangular cavity, the isosceles-trapezoid cavity, the second rectangular cavity, the third rectangular cavity, the fourth rectangular cavity and the fifth rectangular cavity in a front-back direction are located on the same straight line. A length direction of the first rectangular cavity, the second rectangular cavity, the third rectangular cavity, the fourth rectangular cavity and the fifth rectangular cavity is defined as a front-back direction of the first metal plate, and a width direction of the first rectangular cavity, the second rectangular cavity, the third rectangular cavity, the fourth rectangular cavity and the fifth rectangular cavity is defined as a left-right direction of the first metal plate. A right end face of the isosceles-trapezoid cavity is parallel to a left end face of the isosceles-trapezoid cavity and is smaller than the left end face of the isosceles-trapezoid cavity in size, and a front end face of the isosceles-trapezoid cavity is equal to a rear end face of the isosceles-trapezoid cavity. A right end face of the first rectangular cavity is flush with the left end face of the isosceles-trapezoid cavity, a length of the first rectangular cavity is smaller than that of the right end face of the isosceles-trapezoid cavity in the front-back direction of the first metal plate, the left end face of the isosceles-trapezoid cavity overlaps a right end face of the second rectangular cavity and is as large as the right end face of the second rectangular cavity, a left end face of the second rectangular cavity is flush with a right end face of the third rectangular cavity, a length of the third rectangular cavity is greater than that of the second rectangular cavity, a left end face of the third rectangular cavity is flush with a right end face of the fourth rectangular cavity, a length of the fourth rectangular cavity is greater than that of the third rectangular cavity, a left end face of the fourth rectangular cavity is flush with a right end face of the fifth rectangular cavity, and a length of the fifth rectangular cavity is greater than that of the fourth rectangular cavity; a first rectangular metal ridge is arranged in the first rectangular cavity, a right end face of the first rectangular metal ridge is flush with the right end face of the first rectangular cavity, a left end face of the first rectangular metal ridge is flush with a left end face of the first rectangular cavity, a height of the first rectangular metal ridge is half that of the first rectangular cavity, a length of the first rectangular metal ridge in the front-back direction of the first metal plate is smaller than a quarter of the length of the first rectangular cavity, and a distance between a front end face of the first rectangular metal ridge and a front end face of the first rectangular cavity is equal to a distance between a rear end face of the first rectangular metal ridge and a rear end face of the first rectangular cavity. A first rectangular metal base plate and a second rectangular metal ridge are arranged in the isosceles-trapezoid cavity, a height of the first rectangular metal base plate is smaller than a quarter of a height of the isosceles-trapezoid cavity, a right end face of the first rectangular metal base plate is flush with the right end face of the isosceles-trapezoid cavity, a left end face of the first rectangular metal base plate is located in the second rectangular cavity, a length of the first rectangular metal base plate in the front-back direction of the first metal plate is greater than that of the first rectangular cavity and is smaller than that of the right end face of the isosceles-trapezoid cavity in the front-back direction of the first metal base plate, a distance between a front end face of the first rectangular metal base plate and a front end face of the second rectangular cavity is equal to a distance between a rear end face of the first rectangular metal base plate and a rear end face of the second rectangular cavity, a lower end face of the second rectangular metal ridge is attached to a upper end face of the first rectangular metal base plate, a right end face of the second rectangular metal ridge is flush with the left end face of the first rectangular metal ridge, an upper end face of the second rectangular metal ridge and an upper end face of the first rectangular metal ridge are located on the same plane, a length of the second rectangular metal ridge in the left-right direction of the first metal plate is not greater than a quarter of a length of the isosceles-trapezoid cavity in the left-right direction of the first metal plate. A first metal cylinder is arranged on the first rectangular metal base plate, a lower end face of the first metal cylinder is attached to the upper end face of the first rectangular metal base plate, a center of the first metal cylinder is located on a center line of the upper end face of the first rectangular metal base plate in the left-right direction of the first metal plate and is also located on the left end face of the isosceles-trapezoid cavity, a diameter of the first metal cylinder is smaller than a width of the first rectangular metal ridge and is greater than 0.5 mm, and a height of the first metal cylinder is smaller than a quarter of the height of the isosceles-trapezoid cavity. A first rectangular metal baffle is arranged in the second rectangular cavity, a right end face of the first rectangular metal baffle is flush with the left end face of the first rectangular metal base plate, a left end face of the first rectangular metal baffle is flush with the left end face of the second rectangular cavity, a length of the first rectangular metal baffle in the front-back direction of the first metal plate is smaller than that of the first rectangular metal base plate in the front-back direction of the first metal plate and is greater than that of the first rectangular metal ridge in the front-back direction of the first metal plate, the length of the first rectangular metal baffle in the left-right direction of the first metal plate is smaller than half of a width of the second rectangular cavity, a height of the first rectangular metal baffle is equal to that of the second rectangular cavity, and a distance between a front end face of the first rectangular metal baffle and the front end face of the second rectangular cavity is equal to a distance between a rear end face of the first rectangular metal baffle and the rear end face of the second rectangular cavity. A second rectangular metal baffle is arranged in the third rectangular cavity, a right end face of the second rectangular metal baffle is flush with the right end face of the first rectangular metal baffle, a left end face of the second rectangular metal baffle is flush with the left end face of the third rectangular cavity, a length of the second rectangular metal baffle in the front-back direction of the first metal plate is smaller than that of the first rectangular metal baffle in the front-back direction of the first metal plate and is greater than half that of the first rectangular metal baffle in the front-back direction of the first metal plate, a height of the second rectangular metal baffle is equal to that of the third rectangular cavity, and a distance between a front end face of the second rectangular metal baffle and a front end face of the third rectangular cavity is equal to a distance between a rear end face of the second rectangular metal baffle and a rear end face of the third rectangular cavity. A third rectangular metal baffle is arranged in the fourth rectangular cavity, a right end face of the third rectangular metal baffle is flush with the rear end face of the second rectangular metal baffle, a left end face of the third rectangular metal baffle is flush with the left end face of the fourth rectangular cavity, a height of the third rectangular metal baffle is equal to that of the fourth rectangular cavity, a length of the third rectangular metal baffle in the front-back direction of the first metal plate is smaller than the diameter of the first metal cylinder and is greater than 0.5 mm, a distance between a front end face of the third rectangular metal baffle and a front end face of the fourth rectangular cavity is equal to a distance between a rear end face of the third rectangular metal baffle and a rear end face of the fourth rectangular cavity, a second metal cylinder is arranged in the fifth rectangular cavity, a diameter of the second metal cylinder is equal to that of the first metal cylinder, a height of the second metal cylinder is smaller than half that of the fifth rectangular cavity, and a center of the second metal cylinder and a center of the fifth rectangular cavity are located on the same straight line. The H-plane Y-type single-ridge waveguide power divider further comprises a first ridge assembly and a second ridge assembly which are symmetrically arranged in the front-back direction of the first metal plate, and the first ridge assembly comprises a first right-trapezoid metal block, a second right-trapezoid metal block, a first rectangular metal block, a second rectangular metal block, a third rectangular metal block and a fourth rectangular metal block. The first rectangular metal block is located on the first rectangular metal base plate, a lower end face of the first rectangular metal block is attached to the upper end face of the first rectangular metal base plate, a front end face of the first rectangular metal block is flush with the front end face of the first rectangular metal base plate, a length of the first rectangular metal block in the front-back direction of the first metal plate is smaller than one tenth of the length of the first rectangular metal base plate in the front-back direction of the first metal plate, the length of the first rectangular metal block in the left-right direction of the first metal plate is equal to that of the first rectangular metal ridge in the front-back direction of the first metal plate, a sum of a height of the first rectangular metal block and the height of the first rectangular metal base plate is equal to the height of the first rectangular metal ridge, and a distance between a right end face of the first rectangular metal block and the right end face of the first rectangular metal base plate is equal to a distance between a left end face of the first rectangular metal block and the left end face of the first rectangular metal base plate. The first right-trapezoid metal block and the second right-trapezoid metal block are located in the isosceles-trapezoid cavity, the first right-trapezoid metal block is located in front of the first rectangular metal block, a left end face of the first right-trapezoid metal block is parallel to a right end face of the first right-trapezoid metal block, the right end face of the first right-trapezoid metal block is smaller than the left end face of the first right-trapezoid metal block, a rear end face of the first right-trapezoid metal block, the front end face of the first rectangular metal base plate and the front end face of the first rectangular metal block are connected and are located on the same plane, a front end face of the first right-trapezoid metal block is parallel to the front end face of the isosceles-trapezoid cavity, a height of the first right-trapezoid metal block is equal to that of the first rectangular metal ridge, a lower end face of the first right-trapezoid metal block is attached to a lower end face of the isosceles-trapezoid cavity, the second right-trapezoid metal block is located on a left side of the first right-trapezoid metal block, a right end face of the second right-trapezoid metal block and the left end face of the first right-trapezoid metal block are connected and are located on the same plane, a left end face of the second right-trapezoid metal block is parallel to the right end face of the second right-trapezoid metal block, the right end face of the second right-trapezoid metal block is smaller than the left end face of the second right-trapezoid metal block, a front end face of the second right-trapezoid metal block and the front end face of the first right-trapezoid metal block are connected and are located on the same plane, a length of the left end face of the second right-trapezoid metal block in the front-back direction of the first metal plate is equal to that of the first right-trapezoid metal block in the left-right direction of the first metal plate, a height of the second right-trapezoid metal block is equal to that of the first rectangular metal ridge, and a lower end face of the second right-trapezoid metal block is attached to the lower end face of the isosceles-trapezoid cavity. A right end face of the second rectangular metal block overlaps the left end face of the second right-trapezoid metal block, a left end face of the second rectangular metal block is located in the third rectangular cavity, a distance between a front end face of the second rectangular metal block and the front end face of the second rectangular cavity is equal to a distance between a rear end face of the second rectangular metal block and the front end face of the second rectangular metal baffle, a height of the second rectangular metal block is equal to that of the first rectangular metal ridge, a length of a part, located in the third rectangular cavity, of the second rectangular metal block in the left-right direction of the first metal plate is not greater than one third of a width of the third rectangular cavity, and a lower end face of the second rectangular metal block is attached to a lower end face of the second rectangular cavity and a lower end face of the third rectangular cavity. A right end face of the third rectangular metal block overlaps a left end face of the second rectangular block, a left end face of the third rectangular metal block is located in the fourth rectangular cavity, a length of a part, located in the fourth rectangular cavity, of the third rectangular metal block in the left-right direction of the first metal plate is not greater than one fifth of the width of the fourth rectangular cavity, and a height of the third rectangular metal block is smaller than that of the second rectangular metal block and is greater than half that of the second rectangular metal block. A right end face of the fourth rectangular metal block overlaps the left end face of the third rectangular metal block, a rear end face of the fourth rectangular metal block is located in the fifth rectangular cavity, and a length of a part, located in the fifth rectangular cavity, of the fourth rectangular metal block in the left-right direction of the first metal plate is greater than half of a width of the fifth rectangular cavity, and a height of the fourth rectangular metal block is smaller than that of the third rectangular metal block and is greater than half that of the third rectangular metal block. 
     The E-plane T-type single-ridge waveguide power divider comprises a fifth rectangular metal block, wherein a sixth rectangular cavity, a seventh rectangular cavity and an eighth rectangular cavity are sequentially formed in an upper surface of the fifth rectangular metal block from left to right, and the sixth rectangular cavity, the seventh rectangular cavity and the eighth rectangular cavity are sequentially communicated, are identical in height and are as high as the first rectangular cavity. A center line of the sixth rectangular cavity in the left-right direction, a center line of the seventh rectangular cavity in the left-right direction and a center line of the eighth rectangular cavity in the left-right direction are located on the same straight line, a left end face of the sixth rectangular cavity is located on the left end face of the fifth rectangular metal block, a right end face of the sixth rectangular cavity is flush with a left end face of the seventh rectangular cavity, a right end face of the seventh rectangular cavity is flush with a left end face of the eighth rectangular cavity, a right end face of the eighth rectangular cavity is located on a right end face of the fifth rectangular metal block, a rectangular waveguide port is formed below the seventh rectangular cavity, an upper end face of the rectangular waveguide port overlaps a lower end face of seventh rectangular cavity, a lower end face of the rectangular waveguide port is located on a lower end face of the fifth rectangular metal block, a length of the sixth rectangular cavity in the front-back direction and a length of the eighth rectangular cavity in the front-back direction are equal to the length of the first rectangular cavity, the length of the sixth rectangular cavity in the front-back direction is smaller than that of the seventh rectangular cavity in the front-back direction, a third rectangular metal ridge is arranged in the sixth rectangular cavity, a height of the third rectangular metal ridge is smaller than half that of the sixth rectangular cavity, a length of the third rectangular metal ridge in the front-back direction is smaller than half that of the sixth rectangular cavity in the front-back direction, a distance between a front end face of the third rectangular metal ridge and a front end face of the sixth rectangular cavity is equal to a distance between a rear end face of the third rectangular metal ridge and a rear end face of the sixth rectangular cavity, a left end face of the third rectangular metal ridge is flush with the left end face of the sixth rectangular cavity, and a right end face of the third rectangular metal ridge is flush with the right end face of the sixth rectangular cavity. A fourth rectangular metal ridge is arranged in the eighth rectangular cavity, a height of the fourth rectangular metal ridge is smaller than half that of the eighth rectangular cavity, a length of the fourth rectangular metal ridge in the front-back direction is smaller than half that of the eighth rectangular cavity in the front-back direction, a distance between a front end face of the fourth rectangular metal ridge and a front end face of the eighth rectangular cavity is equal to a distance between a rear end face of the fourth rectangular metal ridge and a rear end face of the eighth rectangular cavity, a left end face of the fourth rectangular metal ridge is flush with the left end face of the eighth rectangular cavity, and a right end face of the fourth rectangular metal ridge is flush with the right end face of the eighth rectangular cavity. A first H-plane step and a second H-plane step are arranged in the seventh rectangular cavity, the first H-plane step is located above the second H-plane step, the first H-plane step and the second H-plane step are both rectangular, an upper end face of the first H-plane step is flush with an upper end face of the seventh rectangular cavity, a lower end face of the first H-plane step is attached to an upper end face of the second H-plane step, a left end face of the first H-plane step is attached to the left end face of the seventh rectangular cavity, a right end face of the first H-plane step is attached to the right end face of the seventh rectangular cavity, a front end face of the first H-plane step is attached to a front end face of the seventh rectangular cavity, a rear end face of the first H-plane step is attached to a rear end face of the seventh rectangular cavity, a rear end face of the second H-plane step is connected with the rear end face of the seventh rectangular cavity, a front end face of the second H-plane step is connected with the front end face of the seventh rectangular cavity, a length of the second H-plane step in the left-right direction is smaller than that of the seventh rectangular cavity in the left-right direction, a distance between a left end face of the second H-plane step and the left end face of the seventh rectangular cavity is equal to a distance between a right end face of the second H-plane step and the right end face of the seventh rectangular cavity, a height of the second H-plane step is greater than that of the first H-plane step, and the height of the second H-plane step is smaller than a quarter of a height of the seventh rectangular cavity. When two H-plane Y-type single-ridge waveguide power dividers in each row are connected with one E-plane T-type single-ridge waveguide power divider, the right end face of the first rectangular cavity of the H-plane Y-type single-ridge waveguide power divider on a left side is in butt joint with the left end face of the sixth rectangular cavity of the E-plane T-type single-ridge waveguide power divider, and the right end face of the first rectangular cavity of the H-plane Y-type single-ridge waveguide power divider on a right side is in butt joint with the right end face of the eighth rectangular cavity of the E-plane T-type single-ridge waveguide power divider. In this structure, the first H-plane step and the second H-plane step are used for impedance matching of the E-plane T-type waveguide power divider, so that a return loss is decreased. The third rectangular metal ridge and the forth rectangular metal ridge are used for expanding a bandwidth restrained by traditional waveguide structures, so that a relative bandwidth of the ultra-wideband CTS flat-plate array antenna is increased. 
     The feed network layer comprises a second metal plate and a feed network disposed on the second metal plate, the feed network comprises two feed units which are symmetrically arranged left and right, and the two feed units are connected through an E-plane T-type rectangular-single ridge waveguide power divider. Each feed unit comprises four single ridge waveguide-rectangular waveguide converters and three H-plane T-type single-ridge waveguide power dividers. The four single ridge waveguide-rectangular waveguide converters are sequentially arrayed at intervals from front to back, a first single ridge waveguide-rectangular waveguide converter is connected with a second single ridge waveguide-rectangular waveguide converter through a first H-plane T-type single-ridge waveguide power divider, a third single ridge waveguide-rectangular waveguide converter is connected with a fourth single ridge waveguide-rectangular waveguide converter through a second H-plane T-type single-ridge waveguide power divider, and the first H-plane T-type single-ridge waveguide power divider is connected with the second H-plane T-type single-ridge waveguide power divider through a third H-plane T-type single-ridge waveguide power divider. The third H-plane T-type single-ridge waveguide power dividers in the two feed units are connected with the E-plane T-type rectangular-single ridge waveguide power divider. In this structure, the H-plane T-type single-ridge waveguide power divider can increase the relative bandwidth of the ultra-wideband CTS flat-plate array antenna. 
     The E-plane T-type rectangular-single ridge waveguide power divider comprises a sixth rectangular metal block. A ninth rectangular cavity, a tenth rectangular cavity, an eleventh rectangular cavity, a twelfth rectangular cavity and a thirteenth rectangular cavity are sequentially formed in the sixth rectangular metal block from left to right, the ninth rectangular cavity, the tenth rectangular cavity, the eleventh rectangular cavity, the twelfth rectangular cavity and the thirteenth rectangular cavity are sequentially communicated, a left end face of the ninth rectangular cavity is flush with a left end face of the sixth rectangular metal block, a right end face of the ninth rectangular cavity is flush with a left end face of the tenth rectangular cavity, a right end face of the tenth rectangular cavity is flush with a left end face of the eleventh rectangular cavity, a right end face of the eleventh rectangular cavity is flush with a left end face of the twelfth rectangular cavity, a right end face of the twelfth rectangular cavity is flush with a left end face of the thirteenth rectangular cavity, and a right end face of the thirteenth rectangular cavity is flush with a right end face of the sixth rectangular metal block. An upper end face of the ninth rectangular cavity, an upper end face of the tenth rectangular cavity, an upper end face of the eleventh rectangular cavity, an upper end face of the twelfth rectangular cavity and an upper end face of the thirteenth rectangular cavity are arranged on an upper end face of the sixth rectangular metal block. A lower end face of the ninth rectangular cavity, a lower end face of the tenth rectangular cavity, a lower end face of the eleventh rectangular cavity, a lower end face of the twelfth rectangular cavity and a lower end face of the thirteenth rectangular cavity are located on the same plane and are higher than a lower end face of the sixth rectangular metal block. A length of the ninth rectangular cavity in the left-right direction is greater than that of the tenth rectangular cavity in the left-right direction and is smaller than that of the eleventh rectangular cavity in the left-right direction, the length of the ninth rectangular cavity in the left-right direction is equal to that of the thirteenth rectangular cavity in the left-right direction, and a length of the tenth rectangular cavity is equal to that of the twelfth rectangular cavity in the left-right direction. A front end face of the ninth rectangular cavity, a front end face of the tenth rectangular cavity, a front end face of the eleventh rectangular cavity, a front end face of twelfth rectangular cavity and a front end face of the thirteenth rectangular cavity are located on the same plane and are located behind a front end face of the sixth rectangular metal block. The length of the ninth rectangular cavity in the front-back direction is smaller than that of the tenth rectangular cavity in the front-back direction, the length of the tenth rectangular cavity in the front-back direction is smaller than that of the eleventh rectangular cavity in the front-back direction, the length of the ninth rectangular cavity in the front-back direction is equal to that of the thirteenth rectangular cavity in the front-back direction, and the length of the tenth rectangular cavity in the front-back direction is equal to that of the twelfth rectangular cavity in the front-back direction. The rear end face of the eleventh rectangular cavity is located in front of a rear end face of the sixth rectangular metal block, and a second rectangular metal base plate, a third rectangular metal base plate, a fourth rectangular metal base plate, a fifth rectangular metal base plate and a third H-plane step are arranged in the eleventh rectangular cavity. A front end face of the second rectangular metal base plate, a front end face of the third rectangular metal base plate, a front end face of the fourth rectangular metal base plate and a front end face of the fifth rectangular metal base plate are attached to a front end of the eleventh rectangular cavity. A rear end face of the second rectangular metal base plate, a rear end face of the third rectangular metal base plate, a rear end face of the fourth rectangular metal base plate and a rear end face of the fifth rectangular metal base plate are attached to the rear end face of the eleventh rectangular cavity. A length of the second rectangular metal base plate in the left-right direction is smaller than a quarter of a length of the eleventh rectangular cavity in the left-right direction, the length of the second rectangular metal base plate in the left-right direction is equal to that of the third rectangular metal base plate in the left-right direction, a length of the fourth rectangular metal base plate in the left-right direction is equal to that of the fifth rectangular metal base plate in the left-right direction, a length of the fifth rectangular metal base plate in the left-right direction is smaller than one fifth of a length of the third rectangular metal base plate in the left-right direction, a height of the second rectangular metal base plate, a height of the third rectangular metal base plate, a height of the fourth rectangular metal base plate and a height of the fifth rectangular metal base plate are equal and are smaller than one tenth of a height of the eleventh rectangular cavity, a lower end face of the second rectangular metal base plate and a lower end face of the third rectangular metal base plate are attached to the lower end face of the eleventh rectangular cavity, the fourth rectangular metal base plate is attached to an upper surface of the second rectangular metal base plate, a right end face of the fourth rectangular metal base plate is flush with a right end face of the second rectangular metal base plate, the length of the fourth rectangular metal base plate in the left-right direction is smaller than one fifth of the length of the second rectangular metal base plate in the left-right direction, the fifth rectangular metal base plate is attached to an upper surface of the third rectangular metal base plate, a left end face of the fifth rectangular metal base plate is flush with a left end face of the third rectangular metal base plate, the second rectangular metal base plate is located on a left side of a vertical plane where a center line of the eleventh rectangular cavity in the left-right direction is located, a distance from the right end face of the second rectangular metal base plate to the vertical plane where the center line of the eleventh rectangular cavity in the left-right direction is located is half of a width of a standard waveguide port WR-28, the third rectangular base plate is located on a right side of the vertical plate where the center line of the eleventh rectangular cavity in the left-right direction is located, a distance from the left end face of the third rectangular metal base plate to the vertical plane where the center line of the eleventh rectangular cavity in the left-right direction is located is half of a width of the standard waveguide port WR-28, a front end face of the third H-plane step is attached to the front end face of the eleventh rectangular cavity, a rear end face of the third H-plane step is attached to the rear end face of the eleventh rectangular cavity, an upper end face of the third H-plane step is flush with the upper end face of the sixth rectangular metal block, a vertical plane where a center line of the third H-plane step in the left-right direction is located coincides with the vertical plane where the center line of the eleventh rectangular cavity in the left-right direction is located, a width of the third H-plane step in the left-right direction is smaller than that of the standard waveguide port WR-28, and a height of the third H-plane step is smaller than half that of the eleventh rectangular cavity. A first ridge step is arranged in the ninth rectangular cavity, a second ridge step is arranged in the tenth rectangular cavity, a third ridge step and a fourth ridge step are arranged in the eleventh rectangular cavity, a fifth ridge step is arranged in the twelfth rectangular cavity, a sixth ridge step is arranged in the thirteenth rectangular cavity, and the first ridge step, the second ridge step, the third ridge step, the fourth ridge step, the fifth ridge step and the sixth ridge step are all rectangular. A left end face of the first ridge step is flush with the left end face of the ninth rectangular cavity, a right end face of the first ridge step is flush with the right end face of the ninth rectangular cavity, a height of the first ridge step is smaller than that of the ninth rectangular cavity, a length of the first ridge step in the front-back direction is smaller than that of the ninth rectangular cavity in the front-back direction, a distance between a front end face of the first ridge step and the front end face of the ninth rectangular cavity is equal to a distance between a rear end face of the first ridge step and a rear end face of the ninth rectangular cavity, a left end face of the second ridge step is attached to the right end face of the first ridge step, a right end face of the second ridge step is flush with the right end face of the tenth rectangular cavity, a front end face of the second ridge step is flush with the front end face of the first ridge step, a rear end face of the second ridge step is flush with the rear end face of the first ridge step, a height of the second ridge step is smaller than that of the first ridge step, a left end face of the third ridge step is attached to the right end face of the second ridge step, a right end face of the third ridge step is located in the eleventh rectangular cavity, the right end face of the third ridge step is spaced from a left end face of the second rectangular metal base plate by a certain distance which is smaller than the length of the second rectangular metal base plate in the left-right direction, a front end face of the third ridge step is flush with the front end face of the second ridge step, a rear end face of the third ridge step is flush with the rear end face of the second ridge step, a height of the third ridge step is smaller than that of the second ridge step, a right end face of the fourth ridge step is flush with the right end face of the thirteenth rectangular cavity, a left end face of the fourth ridge step is flush with the left end face of the thirteenth rectangular cavity, a height of the fourth ridge step is equal to that of the first ridge step, a length of the fourth ridge step in the front-back direction is equal to that of the first ridge step in the front-back direction, a distance between a front end face of the fourth ridge step and the front end face of the thirteenth rectangular cavity is equal to a distance between a rear end face of the fourth ridge step and a rear end face of the thirteenth rectangular cavity, a right end face of the fifth ridge step is attached and connected to the left end face of the fourth ridge step, a left end face of the fifth ridge step is flush with a left end face of the twelfth rectangular cavity, a front end face of the fifth ridge step is flush with the front end face of the fourth ridge step, a rear end face of the fifth ridge step is flush with the rear end face of the fourth ridge step, a height of the fifth ridge step is equal to that of the second ridge step, a right end face of the sixth ridge step is attached to the left end face of the fifth ridge step, a left end face of the sixth ridge step is located in the eleventh rectangular cavity, the left end face of the sixth ridge step is spaced from a right end face of the third rectangular metal base plate by a certain distance which is smaller than the length of the third rectangular metal base plate in the left-right direction, a front end face of the sixth ridge step is flush with the front end face of the fifth ridge step, a rear end face of the sixth ridge step is flush with the rear end face of the fifth ridge step, a height of the sixth ridge step is equal to that of the third ridge step, a rectangular waveguide input port communicated with the eleventh rectangular cavity is formed in the sixth rectangular metal block, a lower end of the rectangular waveguide input port is located on the lower end face of the sixth rectangular metal block, an upper end of the rectangular waveguide input port is communicated with the lower end face of the eleventh rectangular cavity, a front end face of the rectangular waveguide input port is flush with the front end face of the eleventh rectangular cavity, a rear end face of the rectangular waveguide input port is flush with the rear end face of the eleventh rectangular cavity, a left end face of the rectangular waveguide input port is flush with the right end face of the second rectangular metal base plate, and a right end face of the rectangular waveguide input port is flush with the left end face of the third rectangular metal base plate. A first output port of the E-plane T-type rectangular-single ridge waveguide power divider is formed in the left end face of the ninth rectangular cavity, a second output port of the E-plane T-type rectangular-single ridge waveguide power divider is formed in the right end face of the thirteenth rectangular cavity, and output ports of the E-plane T-type rectangular-single ridge waveguide power divider are in butt joint with the H-plane T-type single-ridge waveguide power divider. In this structure, the ninth rectangular cavity, the tenth rectangular cavity, the eleventh rectangular cavity, the twelfth rectangular cavity and the thirteenth rectangular cavity can fulfill multi-step transition, so that the bandwidth is increased. The second rectangular metal base plate, the third rectangular metal base plate, the fourth rectangular metal base plate, the fifth rectangular metal base plate and the third H-plane step are used for impedance matching, so that the return loss caused by structural discontinuity is decreased. The first ridge step, the second ridge step, the third ridge step, the fourth ridge step, the fifth ridge step and the sixth ridge step can increase the relative bandwidth of the structure. 
     The H-plane T-type single-ridge waveguide power divider comprises a seventh rectangular block. A fourteenth rectangular cavity and a fifteenth rectangular cavity are formed in the seventh rectangular metal block, the fourteenth rectangular cavity is communicated with the fifteenth rectangular cavity, a front end face of the fourteenth rectangular cavity is flush with a front end face of the seventh rectangular metal block, a rear end face of the seventh rectangular metal block is flush with the front end face of the seventh rectangular metal block, a left end face of the fifteenth rectangular cavity is flush with a left end face of the seventh rectangular metal block, a right end face of the fifteenth rectangular cavity is flush with a left end face of the fourteenth rectangular cavity, a center line of the fifteenth rectangular cavity in the front-back direction and a center line of the seventh rectangular metal block in the front-back direction are located on the same vertical plane, an upper end face of the fourteenth rectangular cavity and an upper end face of the fifteenth rectangular cavity are flush with an upper end face of the seventh rectangular metal block, and a height of the fourteenth rectangular cavity is equal to that of the fifteenth rectangular cavity. A fifth rectangular metal ridge, a sixth rectangular metal base plate and a sixth rectangular metal ridge are sequentially arranged in the fourteenth rectangular cavity from front to back. A front end face of the fifth rectangular metal ridge is flush with the front end face of the fourteenth rectangular cavity, a rear end face of the fifth rectangular metal ridge is flush with a front end face of the fifteenth rectangular cavity, the rear end face of the sixth rectangular metal ridge is flush with a rear end face of the fourteenth rectangular cavity, a front end face of the sixth rectangular metal ridge is flush with a rear end face of the fifteenth rectangular cavity, a height of the fifth rectangular metal ridge is equal to that of the sixth rectangular metal ridge and is equal to half that of the fourteenth rectangular cavity, a length of the fifth rectangular metal ridge in the left-right direction is equal to that of the sixth rectangular metal ridge in the left-right direction, the length of the fifth rectangular metal ridge in the left-right direction is smaller than a quarter of a length of the fourteenth rectangular cavity in the left-right direction, a left end face of the fifth rectangular metal ridge is flush with a left end face of the sixth rectangular metal ridge, a right end face of the fifth rectangular metal ridge is flush with a right end face of the sixth rectangular metal ridge, a front end face of the sixth rectangular metal base plate makes contact with the rear end face of the fifth rectangular metal ridge, a rear end face of the sixth rectangular metal base plate makes contact with the front end face of the sixth rectangular metal ridge, a left end face of the sixth rectangular metal base plate is flush with the left end face of the fourteenth rectangular cavity, a right end face of the sixth rectangular metal base plate is flush with a right end face of the fourteenth rectangular cavity, a height of the sixth rectangular metal base plate is smaller than a quarter of the height of the fourteenth rectangular cavity, a seventh rectangular metal ridge is arranged in the fifteenth rectangular cavity, a left end face of the seventh rectangular metal ridge is flush with the left end face of the fifteenth rectangular cavity, a right end face of the seventh rectangular metal ridge makes contact with the left end face of the sixth rectangular metal base plate, a length of the seventh rectangular metal ridge in the front-back direction is equal to that of the fifth rectangular metal ridge in the left-right direction, a distance between a front end face of the seventh rectangular meal ridge and a front end face of the fifteenth rectangular cavity is equal to a distance between a rear end face of the seventh rectangular metal ridge and the rear end face of the fifteenth rectangular cavity, a length of the fifteenth rectangular cavity in the left-right direction is equal to that of the ninth rectangular cavity in the front-back direction, the left end face of the fifteenth rectangular cavity in the H-plane T-type single-ridge waveguide power divider is in butt joint with the output ports of the E-plane T-type rectangular-single ridge waveguide power divider, and the left end face and the right end face of the fourteenth rectangular cavity in the H-plane T-type single-ridge waveguide power divider are in butt joint with corresponding single ridge waveguide-rectangular waveguide converters. In this structure, the sixth rectangular metal base plate is arranged at a center of the fourteenth rectangular cavity in the H-plane T-type single-ridge waveguide power divider, and the fifth rectangular metal ridge, the sixth rectangular metal ridge, the seventh rectangular metal ridge and the sixth rectangular metal base plate are used for impedance matching, so that the return loss caused by structural discontinuity is decreased, and this structure has a good wideband transmission property. 
     The single ridge waveguide-rectangular waveguide converter comprises an eighth rectangular metal block, a sixteenth rectangular cavity is formed in the eighth rectangular metal block, a first E-plane step is arranged on the left side of the sixteenth rectangular cavity and is rectangular, a height of the first E-plane step is smaller than that of the sixteenth rectangular cavity, the first E-plane step is connected with a front end face, a rear end face and a left end face of the sixteenth rectangular cavity, a fourth H-plane step is arranged on a right side of the sixteenth rectangular cavity and is connected with a right end face and the rear end face of the sixteenth rectangular cavity, a height of the fourth H-plane step is equal to that of the sixteenth rectangular cavity, a rectangular waveguide output port communicated with the sixteenth rectangular cavity is formed in an upper surface of the eighth rectangular metal block, a single-ridge waveguide input port is formed in a front side face of the eighth rectangular metal block and is communicated with the sixteenth rectangular cavity, a height of the single-ridge waveguide input port is equal to that of the sixteenth rectangular cavity, a bottom surface of the single-ridge waveguide input port and a bottom surface of the sixteenth rectangular cavity are located on the same plane, a first ridge step extending onto the bottom surface of the sixteenth rectangular cavity is arranged on the bottom surface of the single-ridge waveguide input port, and comprises a first rectangular ridge and a second rectangular ridge which are sequentially connected, a height of the first rectangular ridge is greater than that of the second rectangular ridge, the height of the first rectangular ridge is smaller than that of the sixteenth rectangular cavity, a size of the single-ridge waveguide input port is matched with that of the left end face of the fourteenth rectangular cavity in the H-plane T-type single-ridge waveguide power divider, the single-ridge waveguide input port is in butt joint with the left end face or the right end face of the fourteenth rectangular cavity in the H-plane T-type single-ridge waveguide power divider. In this structure, the first ridge step, the first E-plane step and the fourth H-plane step are used for impedance matching, so that the return loss caused by structural discontinuity is decreased, and this structure has a good wideband transmission property. 
     Compared with the prior art, the invention has the following advantages: the feed network layer is formed by a plurality of H-plane T-type single-ridge waveguide power dividing networks and a plurality of E-plane T-type rectangular-single ridge waveguide power dividers and is used for converting a single path of TE10 mode signals fed via the standard waveguide port into a plurality of paths of same-power in-phase TE10 mode signals, and all the H-plane T-type single-ridge waveguide power dividing networks fulfills input and output in the same direction, so that the structure is compact, the cut-off frequency can be decreased, the dominant-mode bandwidth is increased, the wide-edge size and the narrow-edge height can be reduced by the H-plane T-type single-ridge waveguide power dividing networks under a given frequency, and a low profile can be realized. The multiple paths of TE10 mode signals are fed into the mode switching layer comprising the first metal plate and the mode switching cavity array disposed on the upper surface of the first metal plate by the E-plane T-type single-ridge waveguide power dividers, the mode switching cavity converts the multiple paths of same-power in-phase TE10 mode signals into four paths of quasi-TEM mode waves by means of the compact-structure wideband H-plane Y-type single-ridge waveguide power dividers, the mode switching layer adjusts the discontinuity of the H-plane Y-type single-ridge waveguide power divider through the first metal base plate and the second metal column and fulfills multi-step transition through the first rectangular cavity, the isosceles-trapezoid cavity, the second rectangular cavity, the third rectangular cavity, the fourth rectangular cavity, the fifth rectangular cavity, the second rectangular metal block, the third rectangular metal block and the fourth rectangular metal block, so that the bandwidth of the antenna is increased, and the antenna has a wide relative bandwidth; and the quasi-TEM waves output by the mode switching cavity are radiated out by the radiating layer to form plane waves, and the CTS flat-plate array antenna can obtain a high gain and a low side lobe under a wideband transmission condition. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a structural view of an ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 2  is an exploded view of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 3  is a top view of a mode switching layer of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 4  is a perspective view of an H-plane Y-type single-ridge waveguide power divider of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 5  is a perspective view of an E-plane T-type single-ridge waveguide power divider of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 6  is a structural view of a feed network layer of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 7  is a perspective view of an E-plane T-type rectangular-single ridge waveguide power divider of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 8  is a perspective view of an H-plane T-type single-ridge waveguide power divider of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 9( a )  is a perspective view of a single ridge waveguide-rectangular waveguide converter of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 9( b )  is an exploded view of the single ridge waveguide-rectangular waveguide converter of the ultra-wideband CTS flat-plate array antenna of the invention; 
         FIG. 10  is a curve chart of a return loss of the ultra-wideband CTS flat-plate array antenna from 25 GHz to 43 GHz of the invention; and 
         FIG. 11  is an E-plane and H-plane direction diagram of the ultra-wideband CTS flat-plate array antenna at 37 GHz of the invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     The invention is further expounded below with reference to the accompanying drawings and embodiments. 
     Embodiment 1 
     As shown in the figures, an ultra-wideband CTS flat-plate array antenna comprises a radiating layer  1 , a mode switching layer  2  and a feed network layer  3  which are sequentially arrayed from top to bottom. The mode switching layer  2  comprises a first metal plate  4  and a mode switching cavity formed in the first metal plate  4 . The mode switching cavity comprises two mode switching units  5  which are identical in structure and are arranged left and right in a spaced manner. Each mode switching unit  5  comprises eight H-plane Y-type single-ridge waveguide power dividers  6  which are arrayed in 4 rows and 2 columns, wherein the H-plane Y-type single-ridge waveguide power divider  6  in the m th  row and 1 st  column is bilaterally symmetrical with the H-plane Y-type single-ridge waveguide power divider  6  in the m th  row and 2 nd  column, and m=1, 2, 3 and 4. The two H-plane Y-type single-ridge waveguide power dividers  6  in each row are connected through an E-plane T-type single-ridge waveguide power divider  7 , and the center distance between every two adjacent H-plane Y-type single-ridge waveguide power dividers  6  in each column is not over one wavelength. 
     The H-plane Y-type single-ridge waveguide power divider  6  in the m th  row and 1 st  column comprises a first rectangular cavity  8 , an isosceles-trapezoid cavity  9 , a second rectangular cavity  10 , a third rectangular cavity  11 , a fourth rectangular cavity  12  and a fifth rectangular cavity  13  which are sequentially formed in an upper end face of the first metal plate  4  from right to left, the first rectangular cavity  8 , the isosceles-trapezoid cavity  9 , the second rectangular cavity  10 , the third rectangular cavity  11 , the fourth rectangular cavity  12  and the fifth rectangular cavity  13  are sequentially communicated front and back, are identical in height and are lower than the first metal plate  4 , and center lines of the first rectangular cavity  8 , the isosceles-trapezoid cavity  9 , the second rectangular cavity  10 , the third rectangular cavity  11 , the fourth rectangular cavity  12  and the fifth rectangular cavity  13  in the front-back direction are located on the same straight line. A length direction of the first rectangular cavity  8 , the second rectangular cavity  10 , the third rectangular cavity  11 , the fourth rectangular cavity  12  and the fifth rectangular cavity  13  is defined as a front-back direction of the first metal plate  4 , and a width direction of the first rectangular cavity  8 , the second rectangular cavity  10 , the third rectangular cavity  11 , the fourth rectangular cavity  12  and the fifth rectangular cavity  13  is defined as a left-right direction of the first metal plate  4 . A right end face of the isosceles-trapezoid cavity  9  is parallel to a left end face of the isosceles-trapezoid cavity  9  and is smaller than the left end face of the isosceles-trapezoid cavity  9  in size, and a front end face of the isosceles-trapezoid cavity  9  is equal to the rear end face of the isosceles-trapezoid cavity  9 . A right end face of the first rectangular cavity  8  is flush with the left end face of the isosceles-trapezoid cavity  9 , a length of the first rectangular cavity  8  is smaller than that of the right end face of the isosceles-trapezoid cavity  9  in the front-back direction of the first metal plate  4 , the left end face of the isosceles-trapezoid cavity  9  overlaps a right end face of the second rectangular cavity  10  and is as large as the right end face of the second rectangular cavity  10 , a left end face of the second rectangular cavity  10  is flush with a right end face of the third rectangular cavity  11 , a length of the third rectangular cavity  11  is greater than that of the second rectangular cavity  10 , a left end face of the third rectangular cavity  11  is flush with a right end face of the fourth rectangular cavity  12 , a length of the fourth rectangular cavity  12  is greater than that of the third rectangular cavity  11 , a left end face of the fourth rectangular cavity  12  is flush with a right end face of the fifth rectangular cavity  13 , and a length of the fifth rectangular cavity  13  is greater than that of the fourth rectangular cavity  12 . A first rectangular metal ridge  14  is arranged in the first rectangular cavity  8 , a right end face of the first rectangular metal ridge  14  is flush with the right end face of the first rectangular cavity  8 , a left end face of the first rectangular metal ridge  14  is flush with a left end face of the first rectangular cavity  8 , a height of the first rectangular metal ridge  14  is half that of the first rectangular cavity  8 , a length of the first rectangular metal ridge  14  in the front-back direction of the first metal plate  4  is smaller than a quarter of the length of the first rectangular cavity  8 , and a distance between a front end face of the first rectangular metal ridge  14  and a front end face of the first rectangular cavity  8  is equal to a distance between a rear end face of the first rectangular metal ridge  14  and a rear end face of the first rectangular cavity  8 . A first rectangular metal base plate  15  and a second rectangular metal ridge  16  are arranged in the isosceles-trapezoid cavity  9 , a height of the first rectangular metal base plate  15  is smaller than a quarter of a height of the isosceles-trapezoid cavity  9 , a right end face of the first rectangular metal base plate  15  is flush with the right end face of the isosceles-trapezoid cavity  9 , a left end face of the first rectangular metal base plate  15  is located in the second rectangular cavity  10 , a length of the first rectangular metal base plate  15  in the front-back direction of the first metal plate  4  is greater than that of the first rectangular cavity  8  and is smaller than that of the right end face of the isosceles-trapezoid cavity  9  in the front-back direction of the first metal base plate  4 , a distance between a front end face of the first rectangular metal base plate  15  and a front end face of the second rectangular cavity  10  is equal to a distance between a rear end face of the first rectangular metal base plate  15  and a rear end face of the second rectangular cavity  10 , a lower end face of the second rectangular metal ridge  16  is attached to an upper end face of the first rectangular metal base plate  15 , a right end face of the second rectangular metal ridge  16  is flush with the left end face of the first rectangular metal ridge  14 , an upper end face of the second rectangular metal ridge  16  and an upper end face of the first rectangular metal ridge  14  are located on the same plane, a length of the second rectangular metal ridge  16  in the left-right direction of the first metal plate  4  is not greater than a quarter of a length of the isosceles-trapezoid cavity  9  in the left-right direction of the first metal plate  4 . A first metal cylinder  17  is arranged on the first rectangular metal base plate  15 , a lower end face of the first metal cylinder  17  is attached to the upper end face of the first rectangular metal base plate  15 , the center of the first metal cylinder  17  is located on the center line of the upper end face of the first rectangular metal base plate  15  in the left-right direction of the first metal plate  4  and is also located on the left end face of the isosceles-trapezoid cavity  9 , a diameter of the first metal cylinder  17  is smaller than a width of the first rectangular metal ridge  14  and is greater than 0.5 mm, and a height of the first metal cylinder  17  is smaller than a quarter of the height of the isosceles-trapezoid cavity  9 . A first rectangular metal baffle  18  is arranged in the second rectangular cavity  10 , a right end face of the first rectangular metal baffle  18  is flush with the left end face of the first rectangular metal base plate  15 , a left end face of the first rectangular metal baffle  18  is flush with the left end face of the second rectangular cavity  10 , a length of the first rectangular metal baffle  18  in the front-back direction of the first metal plate  4  is smaller than that of the first rectangular metal base plate  15  in the front-back direction of the first metal plate  4  and is greater than that of the first rectangular metal ridge  14  in the front-back direction of the first metal plate  4 , the length of the first rectangular metal baffle  18  in the left-right direction of the first metal plate  4  is smaller than half of a width of the second rectangular cavity  10 , a height of the first rectangular metal baffle  18  is equal to that of the second rectangular cavity  10 , and a distance between a front end face of the first rectangular metal baffle  18  and the front end face of the second rectangular cavity  10  is equal to the distance between a rear end face of the first rectangular metal baffle  18  and the rear end face of the second rectangular cavity  10 . A second rectangular metal baffle  19  is arranged in the third rectangular cavity  11 , a right end face of the second rectangular metal baffle  19  is flush with the right end face of the first rectangular metal baffle  18 , a left end face of the second rectangular metal baffle  19  is flush with the left end face of the third rectangular cavity  11 , a length of the second rectangular metal baffle  19  in the front-back direction of the first metal plate  4  is smaller than that of the first rectangular metal baffle  18  in the front-back direction of the first metal plate  4  and is greater than half that of the first rectangular metal baffle  18  in the front-back direction of the first metal plate  4 , a height of the second rectangular metal baffle  19  is equal to that of the third rectangular cavity  11 , and a distance between a front end face of the second rectangular metal baffle  19  and the front end face of the third rectangular cavity  11  is equal to a distance between a rear end face of the second rectangular metal baffle  19  and a rear end face of the third rectangular cavity  11 . A third rectangular metal baffle  20  is arranged in the fourth rectangular cavity  12 , a right end face of the third rectangular metal baffle  20  is flush with the rear end face of the second rectangular metal baffle  19 , a left end face of the third rectangular metal baffle  20  is flush with the left end face of the fourth rectangular cavity  12 , a height of the third rectangular metal baffle  20  is equal to that of the fourth rectangular cavity  12 , a length of the third rectangular metal baffle  20  in the front-back direction of the first metal plate  4  is smaller than the diameter of the first metal cylinder  17  and is greater than 0.5 mm, a distance between a front end face of the third rectangular metal baffle  20  and the front end face of the fourth rectangular cavity  12  is equal to a distance between a rear end face of the third rectangular metal baffle  20  and a rear end face of the fourth rectangular cavity  12 , a second metal cylinder  21  is arranged in the fifth rectangular cavity  13 , a diameter of the second metal cylinder  21  is equal to that of the first metal cylinder  17 , a height of the second metal cylinder  21  is smaller than half that of the fifth rectangular cavity  13 , and a center of the second metal cylinder and a center of the fifth rectangular cavity  13  are located on the same straight line. The H-plane Y-type single-ridge waveguide power divider  6  further comprises a first ridge assembly and a second ridge assembly which are symmetrically arranged in the front-back direction of the first metal plate  4 , and the first ridge assembly comprises a first right-trapezoid metal block  22 , a second right-trapezoid metal block  23 , a first rectangular metal block  24 , a second rectangular metal block  25 , a third rectangular metal block  26  and a fourth rectangular metal block  27 . The first rectangular metal block  24  is located on the first rectangular metal base plate  15 , a lower end face of the first rectangular metal block  24  is attached to the upper end face of the first rectangular metal base plate  15 , a front end face of the first rectangular metal block  24  is flush with the front end face of the first rectangular metal base plate  15 , a length of the first rectangular metal block  24  in the front-back direction of the first metal plate  4  is smaller than one tenth of the length of the first rectangular metal base plate  15  in the front-back direction of the first metal plate  4 , the length of the first rectangular metal block  24  in the left-right direction of the first metal plate  4  is equal to that of the first rectangular metal ridge  14  in the front-back direction of the first metal plate  4 , a sum of a height of the first rectangular metal block  24  and the height of the first rectangular metal base plate  15  is equal to the height of the first rectangular metal ridge  14 , and a distance between a right end face of the first rectangular metal block  24  and the right end face of the first rectangular metal base plate  15  is equal to a distance between a left end face of the first rectangular metal block  24  and the left end face of the first rectangular metal base plate  15 . The first right-trapezoid metal block  22  and the second right-trapezoid metal block  23  are located in the isosceles-trapezoid cavity  9 , the first right-trapezoid metal block  22  is located in front of the first rectangular metal block  24 , a left end face of the first right-trapezoid metal block  22  is parallel to a right end face of the first right-trapezoid metal block  22 , the right end face of the first right-trapezoid metal block  22  is smaller than the left end face of the first right-trapezoid metal block  22 , a rear end face of the first right-trapezoid metal block  22 , the front end face of the first rectangular metal base plate  15  and the front end face of the first rectangular metal block  24  are connected and are located on the same plane, a front end face of the first right-trapezoid metal block  22  is parallel to the front end face of the isosceles-trapezoid cavity  9 , a height of the first right-trapezoid metal block  24  is equal to that of the first rectangular metal ridge  14 , a lower end face of the first right-trapezoid metal block  22  is attached to a lower end face of the isosceles-trapezoid cavity  9 , the second right-trapezoid metal block  23  is located on a left side of the first right-trapezoid metal block  22 , a right end face of the second right-trapezoid metal block  23  and the left end face of the first right-trapezoid metal block  22  are connected and are located on the same plane, a left end face of the second right-trapezoid metal block  23  is parallel to the right end face of the second right-trapezoid metal block  23 , the right end face of the second right-trapezoid metal block  23  is smaller than the left end face of the second right-trapezoid metal block  23 , a front end face of the second right-trapezoid metal block  23  and the front end face of the first right-trapezoid metal block  22  are connected and are located on the same plane, a length of the left end face of the second right-trapezoid metal block  23  in the front-back direction of the first metal plate  4  is equal to that of the first right-trapezoid metal block  22  in the left-right direction of the first metal plate  4 , a height of the second right-trapezoid metal block  23  is equal to that of the first rectangular metal ridge  14 , and a lower end face of the second right-trapezoid metal block  23  is attached to the lower end face of the isosceles-trapezoid cavity  9 . A right end face of the second rectangular metal block  25  overlaps the left end face of the second right-trapezoid metal block  23 , a left end face of the second rectangular metal block  25  is located in the third rectangular cavity  11 , a distance between a front end face of the second rectangular metal block  25  and the front end face of the second rectangular cavity  10  is equal to a distance between a rear end face of the second rectangular metal block  25  and a front end face of the second rectangular metal baffle  19 , a height of the second rectangular metal block  25  is equal to that of the first rectangular metal ridge  14 , a length of a part, located in the third rectangular cavity  11 , of the second rectangular metal block  25  in the left-right direction of the first metal plate  4  is not greater than one third of a width of the third rectangular cavity  11 , and a lower end face of the second rectangular metal block  25  is attached to a lower end face of the second rectangular cavity  10  and a lower end face of the third rectangular cavity  11 . A right end face of the third rectangular metal block  26  overlaps a left end face of the second rectangular block, a left end face of the third rectangular metal block  26  is located in the fourth rectangular cavity  12 , a length of a part, located in the fourth rectangular cavity  12 , of the third rectangular metal block  26  in the left-right direction of the first metal plate  4  is not greater than one fifth of a width of the fourth rectangular cavity  12 , and a height of the third rectangular metal block  26  is smaller than that of the second rectangular metal block  25  and is greater than half that of the second rectangular metal block  25 . A right end face of the fourth rectangular metal block  27  overlaps the left end face of the third rectangular metal block  26 , a rear end face of the fourth rectangular metal block  27  is located in the fifth rectangular cavity  13 , and a length of a part, located in the fifth rectangular cavity  13 , of the fourth rectangular metal block  27  in the left-right direction of the first metal plate  4  is greater than half of a width of the fifth rectangular cavity, and a height of the fourth rectangular metal block  27  is smaller than that of the third rectangular metal block  26  and is greater than half that of the third rectangular metal block  26 . 
     In this embodiment, the E-plane T-type single-ridge waveguide power divider  7  comprises a fifth rectangular metal block  28 . A sixth rectangular cavity  29 , a seventh rectangular cavity  30  and an eighth rectangular cavity  31  are sequentially formed in the upper surface of the fifth rectangular metal block  28  from left to right, and the sixth rectangular cavity  29 , the seventh rectangular cavity  30  and the eighth rectangular cavity  31  are sequentially communicated, are identical in height and are as high as the first rectangular cavity  8 . A center line of the sixth rectangular cavity  29  in the left-right direction, a center line of the seventh rectangular cavity  30  in the left-right direction and a center line of the eighth rectangular cavity  31  in the left-right direction are located on the same straight line, a left end face of the sixth rectangular cavity  29  is located on a left end face of the fifth rectangular metal block  28 , a right end face of the sixth rectangular cavity  29  is flush with a left end face of the seventh rectangular cavity  30 , a right end face of the seventh rectangular cavity  30  is flush with a left end face of the eighth rectangular cavity  31 , a right end face of the eighth rectangular cavity  31  is located on a right end face of the fifth rectangular metal block  28 , a rectangular waveguide port  32  is formed below the seventh rectangular cavity  30 , an upper end face of the rectangular waveguide port  32  overlaps a lower end face of seventh rectangular cavity  30 , a lower end face of the rectangular waveguide port  32  is located on a lower end face of the fifth rectangular metal block  28 , a length of the sixth rectangular cavity  29  in the front-back direction and a length of the eighth rectangular cavity  31  in the front-back direction are equal to the length of the first rectangular cavity  8 , the length of the sixth rectangular cavity  29  in the front-back direction is smaller than that of the seventh rectangular cavity  30  in the front-back direction, a third rectangular metal ridge  33  is arranged in the sixth rectangular cavity  29 , a height of the third rectangular metal ridge  33  is smaller than half that of the sixth rectangular cavity  29 , a length of the third rectangular metal ridge  33  in the front-back direction is smaller than half that of the sixth rectangular cavity  29  in the front-back direction, a distance between a front end face of the third rectangular metal ridge  33  and a front end face of the sixth rectangular cavity  29  is equal to a distance between a rear end face of the third rectangular metal ridge  33  and a rear end face of the sixth rectangular cavity  29 , a left end face of the third rectangular metal ridge  33  is flush with the left end face of the sixth rectangular cavity  29 , and a right end face of the third rectangular metal ridge  33  is flush with the right end face of the sixth rectangular cavity  29 . A fourth rectangular metal ridge  34  is arranged in the eighth rectangular cavity  31 , a height of the fourth rectangular metal ridge  34  is smaller than half that of the eighth rectangular cavity  31 , a length of the fourth rectangular metal ridge  34  in the front-back direction is smaller than half that of the eighth rectangular cavity  31  in the front-back direction, a distance between a front end face of the fourth rectangular metal ridge  34  and a front end face of the eighth rectangular cavity  31  is equal to the distance between a rear end face of the fourth rectangular metal ridge  34  and the rear end face of the eighth rectangular cavity  31 , a left end face of the fourth rectangular metal ridge  34  is flush with the left end face of the eighth rectangular cavity  31 , and a right end face of the fourth rectangular metal ridge  34  is flush with the right end face of the eighth rectangular cavity  31 . A first H-plane step  35  and a second H-plane step  36  are arranged in the seventh rectangular cavity  30 , the first H-plane step  35  is located above the second H-plane step  36 , the first H-plane step  35  and the second H-plane step  36  are both rectangular, an upper end face of the first H-plane step  35  is flush with an upper end face of the seventh rectangular cavity  30 , a lower end face of the first H-plane step  35  is attached to the upper end face of the second H-plane step  36 , a left end face of the first H-plane step  35  is attached to the left end face of the seventh rectangular cavity  30 , a right end face of the first H-plane step  35  is attached to the right end face of the seventh rectangular cavity  30 , a front end face of the first H-plane step  35  is attached to a front end face of the seventh rectangular cavity  30 , a rear end face of the first H-plane step  35  is attached to a rear end face of the seventh rectangular cavity  30 , a rear end face of the second H-plane step  36  is connected with the rear end face of the seventh rectangular cavity  30 , a front end face of the second H-plane step  36  is connected with the front end face of the seventh rectangular cavity  30 , a length of the second H-plane step  36  in the left-right direction is smaller than that of the seventh rectangular cavity  30  in the left-right direction, a distance between a left end face of the second H-plane step  36  and the left end face of the seventh rectangular cavity  30  is equal to a distance between a right end face of the second H-plane step  36  and the right end face of the seventh rectangular cavity  30 , a height of the second H-plane step  36  is greater than that of the first H-plane step  35 , and the height of the second H-plane step  36  is smaller than a quarter of a height of the seventh rectangular cavity  30 . When two H-plane Y-type single-ridge waveguide power dividers  6  in each row are connected with one E-plane T-type single-ridge waveguide power divider  7 , the right end face of the first rectangular cavity  8  of the H-plane Y-type single-ridge waveguide power divider  6  on a left side is in butt joint with the left end face of the sixth rectangular cavity  29  of the E-plane T-type single-ridge waveguide power divider  7 , and the right end face of the first rectangular cavity  8  of the H-plane Y-type single-ridge waveguide power divider  6  on a right side is in butt joint with the right end face of the eighth rectangular cavity  31  of the E-plane T-type single-ridge waveguide power divider  7 . 
     In this embodiment, the radiating layer  1  and the feed network layer  3  are mature products in respective technical fields. 
     Embodiment 2 
     This embodiment is basically identical with embodiment 1 and differs from the Embodiment 1 in the following aspects: 
     In this embodiment, the feed network layer  3  comprises a second metal plate  37  and a feed network disposed on the second metal plate  37 . The feed network comprises two feed units  38  which are symmetrically arranged left and right, and the two feed units  38  are connected through an E-plane T-type rectangular-single ridge waveguide power divider  39 . Each feed unit  38  comprises four single ridge waveguide-rectangular waveguide converters and three H-plane T-type single-ridge waveguide power dividers. The four single ridge waveguide-rectangular waveguide converters are sequentially arrayed at intervals from front to back, a first single ridge waveguide-rectangular waveguide converter  40  is connected with a second single ridge waveguide-rectangular waveguide converter  41  through a first H-plane T-type single-ridge waveguide power divider  42 , a third single ridge waveguide-rectangular waveguide converter  43  is connected with a fourth single ridge waveguide-rectangular waveguide converter  44  through a second H-plane T-type single-ridge waveguide power divider  45 , and the first H-plane T-type single-ridge waveguide power divider  42  is connected with the second H-plane T-type single-ridge waveguide power divider  45  through a third H-plane T-type single-ridge waveguide power divider  46 . The third H-plane T-type single-ridge waveguide power dividers  46  in the two feed units  38  are connected with the E-plane T-type rectangular-single ridge waveguide power divider  39 . 
     In this embodiment, the E-plane T-type rectangular-single ridge waveguide power divider  39  comprises a sixth rectangular metal block  391 . A ninth rectangular cavity  47 , a tenth rectangular cavity  48 , an eleventh rectangular cavity  49 , a twelfth rectangular cavity  50  and a thirteenth rectangular cavity  51  are sequentially formed in the sixth rectangular metal block  391  from left to right, the ninth rectangular cavity  47 , the tenth rectangular cavity  48 , the eleventh rectangular cavity  49 , the twelfth rectangular cavity  50  and the thirteenth rectangular cavity  51  are sequentially communicated, a left end face of the ninth rectangular cavity  47  is flush with a left end face of the sixth rectangular metal block  391 , a right end face of the ninth rectangular cavity  47  is flush with a left end face of the tenth rectangular cavity  48 , a right end face of the tenth rectangular cavity  48  is flush with a left end face of the eleventh rectangular cavity  49 , a right end face of the eleventh rectangular cavity  49  is flush with a left end face of the twelfth rectangular cavity  50 , a right end face of the twelfth rectangular cavity  50  is flush with a left end face of the thirteenth rectangular cavity  51 , and a right end face of the thirteenth rectangular cavity  51  is flush with a right end face of the sixth rectangular metal block  391 . An upper end face of the ninth rectangular cavity  47 , an upper end face of the tenth rectangular cavity  48 , an upper end face of the eleventh rectangular cavity  49 , an upper end face of the twelfth rectangular cavity  50  and an upper end face of the thirteenth rectangular cavity  51  are arranged on an upper end face of the sixth rectangular metal block  391 . A lower end face of the ninth rectangular cavity  47 , a lower end face of the tenth rectangular cavity  48 , a lower end face of the eleventh rectangular cavity  49 , a lower end face of the twelfth rectangular cavity  50  and a lower end face of the thirteenth rectangular cavity  51  are located on the same plane and are higher than a lower end face of the sixth rectangular metal block  391 . A length of the ninth rectangular cavity  47  in the left-right direction is greater than that of the tenth rectangular cavity  48  in the left-right direction and is smaller than that of the eleventh rectangular cavity  49  in the left-right direction, the length of the ninth rectangular cavity  47  in the left-right direction is equal to that of the thirteenth rectangular cavity  51  in the left-right direction, and a length of the tenth rectangular cavity  48  is equal to that of the twelfth rectangular cavity  50  in the left-right direction. A front end face of the ninth rectangular cavity  47 , a front end face of the tenth rectangular cavity  48 , a front end face of the eleventh rectangular cavity  49 , a front end face of twelfth rectangular cavity  50  and a front end face of the thirteenth rectangular cavity  51  are located on the same plane and are located behind a front end face of the sixth rectangular metal block  391 . The length of the ninth rectangular cavity  47  in the front-back direction is smaller than that of the tenth rectangular cavity  48  in the front-back direction, the length of the tenth rectangular cavity  48  in the front-back direction is smaller than that of the eleventh rectangular cavity  49  in the front-back direction, the length of the ninth rectangular cavity  47  in the front-back direction is equal to that of the thirteenth rectangular cavity  51  in the front-back direction, and the length of the tenth rectangular cavity  48  in the front-back direction is equal to that of the twelfth rectangular cavity  50  in the front-back direction. A rear end face of the eleventh rectangular cavity  49  is located in front of a rear end face of the sixth rectangular metal block  391 , and a second rectangular metal base plate  52 , a third rectangular metal base plate  53 , a fourth rectangular metal base plate  54 , a fifth rectangular metal base plate  55  and a third H-plane step  56  are arranged in the eleventh rectangular cavity  49 . A front end face of the second rectangular metal base plate  52 , a front end face of the third rectangular metal base plate  53 , a front end face of the fourth rectangular metal base plate  54  and a front end face of the fifth rectangular metal base plate  55  are attached to a front end of the eleventh rectangular cavity  49 . A rear end face of the second rectangular metal base plate  52 , a rear end face of the third rectangular metal base plate  53 , a rear end face of the fourth rectangular metal base plate  54  and a rear end face of the fifth rectangular metal base plate  55  are attached to the rear end face of the eleventh rectangular cavity  49 . The length of the second rectangular metal base plate  52  in the left-right direction is smaller than a quarter of a length of the eleventh rectangular cavity  49  in the left-right direction, the length of the second rectangular metal base plate  52  in the left-right direction is equal to that of the third rectangular metal base plate  53  in the left-right direction, a length of the fourth rectangular metal base plate  54  in the left-right direction is equal to that of the fifth rectangular metal base plate  55  in the left-right direction, a length of the fifth rectangular metal base plate  55  in the left-right direction is smaller than one fifth of a length of the third rectangular metal base plate  53  in the left-right direction, a height of the second rectangular metal base plate  52 , a height of the third rectangular metal base plate  53 , a height of the fourth rectangular metal base plate  54  and a height of the fifth rectangular metal base plate  55  are equal and are smaller than one tenth of a height of the eleventh rectangular cavity  49 , a lower end face of the second rectangular metal base plate  52  and the lower end face of the third rectangular metal base plate are attached to the lower end face of the eleventh rectangular cavity  49 , the fourth rectangular metal base plate  54  is attached to an upper surface of the second rectangular metal base plate  52 , a right end face of the fourth rectangular metal base plate  54  is flush with a right end face of the second rectangular metal base plate  52 , the length of the fourth rectangular metal base plate  54  in the left-right direction is smaller than one fifth of the length of the second rectangular metal base plate  52  in the left-right direction, the fifth rectangular metal base plate  55  is attached to an upper surface of the third rectangular metal base plate  53 , a left end face of the fifth rectangular metal base plate  55  is flush with a left end face of the third rectangular metal base plate  53 , the second rectangular metal base plate  52  is located on a left side of a vertical plane where a center line of the eleventh rectangular cavity  49  in the left-right direction is located, a distance from the right end face of the second rectangular metal base plate  52  to the vertical plane where the center line of the eleventh rectangular cavity  49  in the left-right direction is located is half of a width of a standard waveguide port WR-28, the third rectangular base plate  53  is located on a right side of the vertical plate where the center line of the eleventh rectangular cavity  49  in the left-right direction is located, a distance from the left end face of the third rectangular metal base plate  53  to the vertical plane where the center line of the eleventh rectangular cavity  49  in the left-right direction is located is half of a width of the standard waveguide port WR-28, a front end face of the third H-plane step  56  is attached to the front end face of the eleventh rectangular cavity  49 , a rear end face of the third H-plane step  56  is attached to the rear end face of the eleventh rectangular cavity  49 , an upper end face of the third H-plane step  56  is flush with the upper end face of the sixth rectangular metal block  391 , a vertical plane where a center line of the third H-plane step  56  in the left-right direction is located coincides with the vertical plane where the center line of the eleventh rectangular cavity  49  in the left-right direction is located, a width of the third H-plane step  56  in the left-right direction is smaller than that of the standard waveguide port WR-28, and a height of the third H-plane step  56  is smaller than half that of the eleventh rectangular cavity  49 . A first ridge step  57  is arranged in the ninth rectangular cavity  47 , a second ridge step  58  is arranged in the tenth rectangular cavity  48 , a third ridge step  59  and a fourth ridge step  60  are arranged in the eleventh rectangular cavity  49 , a fifth ridge step  61  is arranged in the twelfth rectangular cavity  50 , a sixth ridge step  62  is arranged in the thirteenth rectangular cavity  51 , and the first ridge step  57 , the second ridge step  58 , the third ridge step  59 , the fourth ridge step  60 , the fifth ridge step  61  and the sixth ridge step  62  are all rectangular. A left end face of the first ridge step  57  is flush with the left end face of the ninth rectangular cavity  47 , a right end face of the first ridge step  57  is flush with a right end face of the ninth rectangular cavity  47 , a height of the first ridge step  57  is smaller than that of the ninth rectangular cavity  47 , a length of the first ridge step  57  in the front-back direction is smaller than that of the ninth rectangular cavity  47  in the front-back direction, a distance between a front end face of the first ridge step  57  and the front end face of the ninth rectangular cavity  47  is equal to a distance between a rear end face of the first ridge step  57  and a rear end face of the ninth rectangular cavity  47 , a left end face of the second ridge step  58  is attached to the right end face of the first ridge step  57 , a right end face of the second ridge step  58  is flush with the right end face of the tenth rectangular cavity  48 , a front end face of the second ridge step  58  is flush with the front end face of the first ridge step  57 , a rear end face of the second ridge step  58  is flush with the rear end face of the first ridge step  57 , a height of the second ridge step  58  is smaller than that of the first ridge step  57 , a left end face of the third ridge step  59  is attached to the right end face of the second ridge step  58 , a right end face of the third ridge step  59  is located in the eleventh rectangular cavity  49 , the right end face of the third ridge step  59  is spaced from a left end face of the second rectangular metal base plate  52  by a certain distance which is smaller than the length of the second rectangular metal base plate  52  in the left-right direction, a front end face of the third ridge step  59  is flush with the front end face of the second ridge step  58 , a rear end face of the third ridge step  59  is flush with the rear end face of the second ridge step  58 , a height of the third ridge step  59  is smaller than that of the second ridge step  58 , a right end face of the fourth ridge step  60  is flush with the right end face of the thirteenth rectangular cavity  51 , a left end face of the fourth ridge step  60  is flush with the left end face of the thirteenth rectangular cavity  51 , a height of the fourth ridge step  60  is equal to that of the first ridge step  57 , a length of the fourth ridge step  60  in the front-back direction is equal to that of the first ridge step  57  in the front-back direction, a distance between a front end face of the fourth ridge step  60  and the front end face of the thirteenth rectangular cavity  51  is equal to a distance between a rear end face of the fourth ridge step  60  and a rear end face of the thirteenth rectangular cavity  51 , a right end face of the fifth ridge step  61  is attached and connected to the left end face of the fourth ridge step  60 , a left end face of the fifth ridge step  61  is flush with the left end face of the twelfth rectangular cavity  50 , a front end face of the fifth ridge step  61  is flush with the front end face of the fourth ridge step  60 , a rear end face of the fifth ridge step  61  is flush with the rear end face of the fourth ridge step  60 , a height of the fifth ridge step  61  is equal to that of the second ridge step  58 , a right end face of the sixth ridge step  62  is attached to the left end face of the fifth ridge step  61 , a left end face of the sixth ridge step  62  is located in the eleventh rectangular cavity  49 , the left end face of the sixth ridge step  62  is spaced from a right end face of the third rectangular metal base plate  53  by a certain distance which is smaller than the length of the third rectangular metal base plate  53  in the left-right direction, a front end face of the sixth ridge step  62  is flush with the front end face of the fifth ridge step  61 , a rear end face of the sixth ridge step  62  is flush with the rear end face of the fifth ridge step  61 , a height of the sixth ridge step  62  is equal to that of the third ridge step  59 , a rectangular waveguide input port  63  communicated with the eleventh rectangular cavity  49  is formed in the sixth rectangular metal block  391 , a lower end of the rectangular waveguide input port  63  is located on the lower end face of the sixth rectangular metal block  391 , an upper end of the rectangular waveguide input port  63  is communicated with the lower end face of the eleventh rectangular cavity  49 , a front end face of the rectangular waveguide input port  63  is flush with the front end face of the eleventh rectangular cavity  49 , a rear end face of the rectangular waveguide input port  63  is flush with the rear end face of the eleventh rectangular cavity  49 , a left end face of the rectangular waveguide input port  63  is flush with the right end face of the second rectangular metal base plate  52 , and a right end face of the rectangular waveguide input port  63  is flush with the left end face of the third rectangular metal base plate  53 . A first output port of the E-plane T-type rectangular-single ridge waveguide power divider  39  is formed in the left end face of the ninth rectangular cavity  47 , a second output port of the E-plane T-type rectangular-single ridge waveguide power divider  39  is formed in the right end face of the thirteenth rectangular cavity  51 , and output ports of the E-plane T-type rectangular-single ridge waveguide power divider  39  are in butt joint with the H-plane T-type single-ridge waveguide power divider. 
     In this embodiment, the H-plane T-type single-ridge waveguide power divider comprises a seventh rectangular block  64 . A fourteenth rectangular cavity  65  and a fifteenth rectangular cavity  66  are formed in the seventh rectangular metal block  64 , the fourteenth rectangular cavity  65  is communicated with the fifteenth rectangular cavity  66 , a front end face of the fourteenth rectangular cavity  65  is flush with a front end face of the seventh rectangular metal block  64 , a rear end face of the seventh rectangular metal block  64  is flush with the front end face of the seventh rectangular metal block  64 , a left end face of the fifteenth rectangular cavity  66  is flush with a left end face of the seventh rectangular metal block  64 , a right end face of the fifteenth rectangular cavity  66  is flush with a left end face of the fourteenth rectangular cavity  65 , a center line of the fifteenth rectangular cavity  66  in the front-back direction and a center line of the seventh rectangular metal block  64  in the front-back direction are located on the same vertical plane, an upper end face of the fourteenth rectangular cavity  65  and an upper end face of the fifteenth rectangular cavity  66  are flush with an upper end face of the seventh rectangular metal block  64 , and a height of the fourteenth rectangular cavity  65  is equal to that of the fifteenth rectangular cavity  66 . A fifth rectangular metal ridge  67 , a sixth rectangular metal base plate  68  and a sixth rectangular metal ridge  69  are sequentially arranged in the fourteenth rectangular cavity  65  from front to back. A front end face of the fifth rectangular metal ridge  67  is flush with the front end face of the fourteenth rectangular cavity  65 , a rear end face of the fifth rectangular metal ridge  67  is flush with a front end face of the fifteenth rectangular cavity  66 , a rear end face of the sixth rectangular metal ridge  69  is flush with a rear end face of the fourteenth rectangular cavity  65 , a front end face of the sixth rectangular metal ridge  69  is flush with a rear end face of the fifteenth rectangular cavity  66 , a height of the fifth rectangular metal ridge  67  is equal to that of the sixth rectangular metal ridge  69  and is equal to half that of the fourteenth rectangular cavity  65 , a length of the fifth rectangular metal ridge  67  in the left-right direction is equal to that of the sixth rectangular metal ridge  69  in the left-right direction, the length of the fifth rectangular metal ridge  67  in the left-right direction is smaller than a quarter of a length of the fourteenth rectangular cavity  65  in the left-right direction, a left end face of the fifth rectangular metal ridge  67  is flush with a left end face of the sixth rectangular metal ridge  69 , a right end face of the fifth rectangular metal ridge  67  is flush with a right end face of the sixth rectangular metal ridge  69 , a front end face of the sixth rectangular metal base plate  68  makes contact with the rear end face of the fifth rectangular metal ridge  67 , a rear end face of the sixth rectangular metal base plate  68  makes contact with the front end face of the sixth rectangular metal ridge  69 , a left end face of the sixth rectangular metal base plate  68  is flush with the left end face of the fourteenth rectangular cavity  65 , a right end face of the sixth rectangular metal base plate  68  is flush with a right end face of the fourteenth rectangular cavity  65 , a height of the sixth rectangular metal base plate  68  is smaller than a quarter of the height of the fourteenth rectangular cavity  65 , a seventh rectangular metal ridge  70  is arranged in the fifteenth rectangular cavity  66 , a left end face of the seventh rectangular metal ridge  70  is flush with the left end face of the fifteenth rectangular cavity  66 , a right end face of the seventh rectangular metal ridge  70  makes contact with the left end face of the sixth rectangular metal base plate  68 , a length of the seventh rectangular metal ridge  70  in the front-back direction is equal to that of the fifth rectangular metal ridge  67  in the left-right direction, a distance between a front end face of the seventh rectangular meal ridge  70  and the front end face of the fifteenth rectangular cavity  66  is equal to a distance between a rear end face of the seventh rectangular metal ridge  70  and the rear end face of the fifteenth rectangular cavity  66 , a length of the fifteenth rectangular cavity  66  in the left-right direction is equal to that of the ninth rectangular cavity  47  in the front-back direction, the left end face of the fifteenth rectangular cavity  66  in the H-plane T-type single-ridge waveguide power divider is in butt joint with the output ports of the E-plane T-type rectangular-single ridge waveguide power divider  39 , and a left end face and a right end face of the H-plane T-type single-ridge waveguide power divider are in butt joint with the corresponding single ridge waveguide-rectangular waveguide converters. 
     In this embodiment, the single ridge waveguide-rectangular waveguide converter comprises an eighth rectangular metal block  71 , a sixteenth rectangular cavity  72  is formed in the eighth rectangular metal block  71 , a first E-plane step  73  is arranged on a left side of the sixteenth rectangular cavity  72  and is rectangular, a height of the first E-plane step  73  is smaller than that of the sixteenth rectangular cavity  72 , the first E-plane step  73  is connected with a front end face, a rear end face and a left end face of the sixteenth rectangular cavity  72 , a fourth H-plane step  74  is arranged on the right side of the sixteenth rectangular cavity  72  and is connected with a right end face and a rear end face of the sixteenth rectangular cavity  72 , a height of the fourth H-plane step  74  is equal to that of the sixteenth rectangular cavity  72 , a rectangular waveguide output port  75  communicated with the sixteenth rectangular cavity  72  is formed in an upper surface of the eighth rectangular metal block  71 , a single-ridge waveguide input port  76  is formed in a front side face of the eighth rectangular metal block  71  and is communicated with the sixteenth rectangular cavity  72 , a height of the single-ridge waveguide input port  76  is equal to that of the sixteenth rectangular cavity  72 , a bottom surface of the single-ridge waveguide input port  76  and a bottom surface of the sixteenth rectangular cavity  72  are located on the same plane, a first ridge step extending onto the bottom surface of the sixteenth rectangular cavity  72  is arranged on the bottom surface of the single-ridge waveguide input port  76 , and comprises a first rectangular ridge  77  and a second rectangular ridge  78  which are sequentially connected, a height of the first rectangular ridge  77  is greater than that of the second rectangular ridge  78 , the height of the first rectangular ridge  77  is smaller than that of the sixteenth rectangular cavity  72 , a size of the single-ridge waveguide input port  76  is matched with that of the left end face of the fourteenth rectangular cavity  65  in the H-plane T-type single-ridge waveguide power divider, the single-ridge waveguide input port  76  is in butt joint with the left end face or the right end face of the fourteenth rectangular cavity  65  in the H-plane T-type single-ridge waveguide power divider. 
       FIG. 10  shows a curve chart of a return loss of the ultra-wideband CTS flat-plate array antenna from 25 GHz to 43 GHz of the invention. As can be seen from  FIG. 10 , within the range from 26 GHz to 42 GHz (relative bandwidth 47.1%), a return loss of the ultra-wideband CTS flat-plate array antenna is lower than −10 dB, and thus, an ultra-bandwidth objective is fulfilled. 
       FIG. 11  shows an E-plane and H-plane direction diagram of the ultra-wideband CTS flat-plate array antenna at 37 GHz of the invention. As can be seen from  FIG. 11 , a gain of the ultra-wideband CTS flat-plate array antenna at 37 GHz within the whole frequency band is superior to 27 dBi, and a high gain is realized.