| 摘要 |
An antenna comprises first and second conducting elements 12a, 12b and first, second and third conducting lines 16, 18, 24. Each conducting element 12a, 12b has a conductive surface 14a, 14b. The first conducting line 16 provides a short circuit between the conductive surfaces 14a, 14b. The second conducting line has a first end electrically connected to one conductive surface 14a and a second, free end 22. The third conducting line has a first end electrically connected to the other conductive surface 14b and a second, free end 28. The second and third conducting lines 18, 24 are aligned along an axis X-X and each of the second ends 22, 28 of the second and third conducting lines 18, 24 serves as one of the terminals of a two terminal port F for feeding an RF signal of wavelength » to the antenna. The first and second conducting elements 12a, 12b are arranged with the conductive surfaces 14a, 14b in a face-to-face relationship, spaced apart by a distance d and the first, second and third conducting lines 16, 18, 24 are arranged such that, when an RF signal is fed to the antenna, currents C1 caused to flow in one conductive surface 14a generate a magnetic field that at least partially cancels out the magnetic field generated by currents C2 caused to flow in the other conductive surface 14b, and currents are caused to flow in the first, second and third conducting lines 16, 18, 24, the currents caused to flow in the second and third conducting lines 18, 24 having two components, a first component C3 generating a magnetic field that at least partially cancels out the magnetic field generated by the same current C3 flowing in the first conducting line and a second component C4 acting as the effective antenna current that generates an E-field vector along the axis of alignment X-X of the second and third conducting lines 18, 24. |
