36results about How to "Guaranteed Radiation Efficiency" patented technology

The invention relates to a loudspeaker box structure which comprises a loudspeaker and a loudspeaker box cavity, wherein the loudspeaker is arranged in the loudspeaker box cavity; the loudspeaker box cavity comprises a reversed cavity unit and a positive cavity unit; the reversed cavity unit is connected with the positive cavity unit; the loudspeaker is arranged between the reversed cavity unit and the positive cavity unit; the reversed cavity unit comprises at least one reversed resonant cavity; and the positive cavity unit comprises at least one positive resonant cavity. A positive radiating sound wave of the loudspeaker is transmitted after being resonated and tuned by the positive cavity unit; meanwhile, the reversed radiating sound wave of the loudspeaker can be transmitted after being resonated and tuned by the reversed cavity unit. The frequency lower limit of the resonated and tuned radiating sound wave is far lower than the lower limit of the reversed radiating sound wave andthe positive radiating sound wave of the loudspeaker; the number of the positive resonant cavities and the reversed resonant cavities is adjusted so that the two sound saves are laminated in same phase; and the invention ensures the radiating efficiency of the loudspeaker box, reduces the low-frequency playback lower limit of the loudspeaker box, improves the sound quality and has the advantages of smaller caliber of the loudspeaker and smaller size of the loudspeaker box.

The invention proposes a low radar scattering cross-section reflection array antenna, which mainly solves the problems of the existing radar scattering cross-section reduction frequency band and narrow angle range of the reflection array antenna. It includes a feed source (1) and a reflection front (2) located below the feed source, the reflection front includes M×N reflection units (3) with the same structure and different parameters, each reflection unit includes four dielectric substrates And the metal surface printed on each medium substrate, each metal surface is composed of upper and lower metal branches and metal branches, wherein the upper metal branch is composed of three metal patches, and the lower metal branch is composed of five metal patches Composition, four dielectric substrates are laminated in pairs to form two laminated dielectric substrates (31, 32), and the two laminated dielectric substrates are placed vertically to form a cross-shaped structure. While ensuring the radiation efficiency of the reflection array antenna, the invention realizes the reduction of the radar scattering section in the range of wide frequency band and wide angle domain, and can be used in various long-distance wireless communication systems.