| 摘要 |
PURPOSE: To attain multi-resonance without using any multi-resonance matching circuit and to provide a satisfactory directivity and both polarization radiation characteristics in the direction along a wall when the device is mounted on the surface of the wall. CONSTITUTION: This antenna device is a loop antenna folded in a U-shape, and both parallel parts 1a, 2a of an L-shape element and a center element 3 are set at λ/2 (λ: fundamental resonance wavelength of antenna), and orthogonal parts 1b, 2b are set at λ/4. The terminal part of the orthogonal part 1b is connected to a coaxial feed line 6, and that of the orthogonal part 2b to a ground metallic plate 5. An L-shape branch element 4 (or linear branch element 4') is connected to a point within 0.3λfrom the center element 3 or an L-shape element 2 on its extension, therefore, a second resonance frequency different from a reference resonance frequency is set. The length of the branch element is decided depending on the size of the element. Further multi-resonance can be obtained by increasing the number of branch elements. |
